INTERNET-DRAFT J. Loughney (Editor) Internet Engineering Task Force Nokia G. Sidebottom, Guy Mousseau Issued: 20 July 2001 Nortel Networks Expires: 20 January 2002 S. Lorusso Unisphere Solutions L. Coene, G. Verwimp Siemens J. Keller Tekelec F. Escobar Ericsson W. Sully, S. Furniss Marconi SS7 SCCP-User Adaptation Layer (SUA) Status of This Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as 'work in progress.' The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This draft expires on 20 January 2002 Abstract This Internet Draft defines a protocol for the transport of any SS7 SCCP-User signaling (e.g., TCAP, RANAP, etc.) over IP using the Stream Control Transport Protocol. The protocol should be modular and symmetric, to allow it to work in diverse architectures, such as a Signaling Gateway to IP Signaling Endpoint architecture as well as a peer-to-peer IP Signaling Endpoint architecture. Protocol elements are added to allow seamless operation between peers in the SS7 and IP domains. Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Abstract.............................................................1 1. Introduction......................................................3 1.1 Scope...........................................................3 1.2 Terminology.....................................................3 1.3 Signaling Transport Architecture................................5 1.4 Services Provided by the SUA Layer.............................12 1.5 Internal Functions Provided in the SUA Layer...................14 1.6 Definition of SUA Boundaries...................................16 2 Conventions.......................................................17 3 Protocol Elements.................................................17 3.1 Common Message Header..........................................17 3.2 SUA Connectionless Messages....................................21 3.3 Connection Oriented Messages...................................23 3.4 Signaling Network Management Messages..........................32 3.5 Application Server Process State Maintenance Messages..........37 3.6 ASP Traffic Maintenance Messages...............................40 3.7 SUA Management Messages........................................43 3.8 Common Parameters..............................................44 3.9 SUA-Specific parameters........................................53 4 Procedures........................................................64 4.1 SCCP û SUA Interworking at the SG..............................65 4.2 Primitives received from the local SUA-user....................67 4.3 Layer Management Procedures....................................67 4.4 SUA Management Procedures......................................68 5 Examples of SUA Procedures........................................76 5.1 SG Architecture................................................76 5.2 IP-IP Architecture.............................................78 6 Security..........................................................80 6.1 Introduction...................................................80 6.2 Threats........................................................80 6.3 Protecting Confidentiality.....................................81 7 IANA Considerations...............................................81 7.1 SCTP Payload Protocol ID.......................................81 7.2 Port Number....................................................81 7.3 Protocol Extensions............................................81 8 Timer Values......................................................83 9 Acknowledgements..................................................83 10 Authors' Addresses...............................................83 11 References.......................................................84 Copyright Statement.................................................87 Loughney (editor) [Page 2] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 1. Introduction 1.1 Scope There is on-going integration of SCN networks and IP networks. Network service providers are designing all IP architectures that include support for SS7 and SS7-like signaling protocols. IP provides an effective way to transport user data and for operators to expand their networks and build new services. In these networks, there may be some need for interworking between the SS7 and IP domains. This document details the delivery of SCCP-user messages (MAP & CAP over TCAP, RANAP, etc.) and new third generation network protocol messages over IP between two signaling endpoints. Consideration is given for the transport from an SS7 Signaling Gateway (SG) to an IP signaling node (such as an IP-resident Database) as described in the Framework Architecture for Signaling Transport [2719]. This protocol can also support transport of SCCP-user messages between two endpoints wholly contained within an IP network. The delivery mechanism addresses the following criteria: * Support for transfer of SCCP-User Part messages (TCAP, RANAP, etc.) * Support for SCCP connectionless service. * Support for SCCP connection oriented service. * Support for the seamless operation of SCCP-User protocol peers. * Support for the management of SCTP transport associations between a SG and one or more IP-based signaling nodes). * Support for distributed IP-based signaling nodes. * Support for the asynchronous reporting of status changes to management. The protocol is modular in design, allowing different implementations to be made, based upon the environment that needs to be supported. Depending upon the upper layer protocol supported, the SUA will need to support SCCP connectionless service, SCCP connect- oriented service or both services. 1.2 Terminology Signaling Gateway (SG) - Network element that terminates SCN signaling and transports SCCP-User signaling over IP to an IP signaling endpoint. A Signaling Gateway could be modeled as one or more Signaling Gateway Processes, which are located at the border of the SS7 and IP networks. Application Server (AS) - A logical entity serving a specific Routing Key. An example of an Application Server is a virtual IP Loughney (editor) [Page 3] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 database element handling all requests for a SCCP-user. The AS contains a set of one or more unique Application Server Processes, of which one or more is normally actively processing traffic. Application Server Process (ASP) - An Application Server Process serves as an active or backup process of an Application Server (e.g., part of a distributed signaling node or database element). Examples of ASPs are MGCs, IP SCPs, or IP-based HLRs. An ASP contains an SCTP end-point and may be configured to process traffic within more than one Application Server. IP Server Process (IPSP) - A process instance of an IP-based application. An IPSP is essentially the same as an ASP, except that it uses SUA in a peer-to-peer fashion. Conceptually, an IPSP does not use the services of a Signaling Gateway. Signaling Gateway Process (SGP) - A process instance of a Signaling Gateway. It serves as an active, standby or load-sharing process of a Signaling Gateway. Signaling Process - A process instance that uses SUA to communicate with other signaling process. An ASP, a SGP and an IPSP are all signaling processes. Association - An association refers to an SCTP association. The association provides the transport for the delivery of SCCP-User protocol data units and SUA layer peer messages. Routing Key - The Routing Key describes a set of SS7 parameters and/or parameter-ranges that uniquely defines the range of signaling traffic configured to be handled by a particular Application Server. An example would be where a Routing Key consists of a particular SS7 SCCP SSN plus an identifier to uniquely mark the network that the SSN belongs to, for which all traffic would be directed to a particular Application Server. Routing Keys are mutually exclusive in the sense that a received SS7 signaling message cannot be directed to more than one Routing Key. Routing Keys can be provisioned, for example, by a MIB. Routing Context - An Application Server Process may be configured to process traffic within more than one Application Server. In this case, the Routing Context parameter is exchanged between the SGP and the ASP (or between two ASPs), identifying the relevant Application Server. From the perspective of an SGP/ASP, the Routing Context uniquely identifies the range of traffic associated with a particular Application Server, which the ASP is configured to receive. There is a 1:1 relationship between a Routing Context value and a Routing Key within an AS. Therefore the Routing Context can be viewed as an index into an AS Table containing the AS Routing Keys. The Routing Context also uniquely identifies an SS7 entity (point code) into a SS7 network, as presented by the SG. Loughney (editor) [Page 4] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Address Mapping Function (AMF) - The AMF is an implementation dependent function that is responsible for resolving the address presented in the incoming SCCP/SUA message to correct SCTP association for the desired endpoint. The AMF MAY use routing context / rouging key information as selection criteria for the appropriate SCTP association. Fail-over - The capability to re-route signaling traffic as required to an alternate Application Server Process, or group of ASPs, within an Application Server in the event of failure or unavailability of a currently used Application Server Process. Fail-over may apply upon the return to service of a previously unavailable Application Server Process. Network Byte Order - Most significant byte first, a.k.a. Big Endian. Layer Management - Layer Management is a nodal function that handles the inputs and outputs between the M3UA layer and a local management entity. Host - The computing platform that the SGP or ASP process is running on. Stream - A stream refers to an SCTP stream; a uni-directional logical channel established from one SCTP endpoint to another associated SCTP endpoint, within which all user messages are delivered in-sequence except for those submitted to the un-ordered delivery service. Transport address - an address that serves as a source or destination for the unreliable packet transport service used by SCTP. In IP networks, a transport address is defined by the combination of an IP address and an SCTP port number. Note, only one SCTP port may be defined for each endpoint, but each SCTP endpoint may have multiple IP addresses. 1.3 Signaling Transport Architecture The framework architecture that has been defined for SCN signaling transport over IP [2719] uses multiple components, including an IP transport protocol, a signaling common transport protocol and an adaptation module to support the services expected by a particular SCN signaling protocol from its underlying protocol layer. In general terms, the SUA architecture can be modeled as a peer-to- peer architecture. The first section considers the SS7-IP interworking architectures for connectionless and connection- oriented transport. For this case, it is assumed that the ASP initiates the establishment of the SCTP association with SG. Loughney (editor) [Page 5] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 1.3.1 Protocol Architecture for Connectionless Transport In this architecture, the SCCP and SUA layers interface in the SG. There needs to be interworking between the SCCP and SUA layers to provide for the seamless transfer of the user messages as well as the management messages. For messages destined for an ASP, there are two scenarios. ******** SS7 *************** IP ******** * SEP *---------* *--------* * * or * * SG * * ASP * * STP * * * * * ******** *************** ******** +------+ +------+ | SUAP | | SUAP | +------+ +------+------+ +------+ | SCCP | | SCCP | SUA | | SUA | +------+ +------+------+ +------+ | MTP3 | | MTP3 | | | | +------| +------+ SCTP | | SCTP | | MTP2 | | MTP2 | | | | +------+ +------+------+ +------+ | L1 | | L1 | IP | | IP | +------+ +------+------+ +------+ | | | | +---------------+ +------------+ SUAP - SCCP/SUA User Protocol (TCAP, for example) STP - SS7 Signaling Transfer Point 1.3.1.1 SG as endpoint In this case, the connectionless SCCP messages are routed on PC and SSN. The subsystem identified by SSN and Routing Context is regarded as local to the SG. This means from SS7 point of view, the SCCP-user is located at the SG. By means of configuration, the SG knows the local SCCP-user is actually represented by an AS, and serviced by a set of ASPs working in n+k redundancy mode. An ASP is selected and a CLDT message is sent on the appropriate SCTP association/stream. The selection criterion can be based on a round robin mechanism, or any other method that guarantees a balanced load sharing over the active ASPs. However, when TCAP messages are transported, load sharing is only possible for the first message in a TCAP dialogue (TC_Begin, TC_Query, TC_Unidirectional). All other TCAP messages in the same dialogue are sent to the same ASP that was selected for the first message, unless the ASPs are able to share state and maintain Loughney (editor) [Page 6] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 in sequence delivery. To this end, the SGP needs to know the TID allocation policy of the ASPs in a single AS: - State sharing - Fixed range of TIDs per ASP in the AS This information may be preconfigured in the SG, or may be dynamically exchanged via the ASP_Active message. An example for a INAP/TCAP message exchange between SEP and ASP is given below. Address information in CLDT message (e.g. TC_Query) from SGP to ASP, with association ID = SG-ASP, Stream ID based on SLS and possibly other parameters, e.g. OPC or Network ID: - Routing Context: based on SS7 Network ID and AS membership, so that the message can be transported to the correct ASP. - Source address: valid combination of SSN, PC and GT, as needed for back routing to the SEP. - Destination address: at least SSN, to select the SCCP/SUA- user at the ASP. Address information in CLDT message (e.g. TC_Response) from ASP to SG, with association ID = ASP-SG, stream ID selected by implementation dependent means with regards to in-sequence-delivery: - Routing Context: as received in previous message. - Source address: unique address provided so that when used as the SCCP called party address in the SEP, it MUST yield the same AS, the SSN might be sufficient. - Destination address: copied from source address in received CLDT message. Further messages from the SEP belonging to the same TCAP transaction will now reach the same ASP. 1.3.1.2 SG as relay-point A Global Title translation is executed at the SG, before the destination of the message can be determined. The actual location of the SCCP-user is irrelevant to the SS7 network. GT Translation yields an "SCCP entity set", which now may contain one or more ASÆs. Selection of the AS is thus based on the SCCP called party address (and possibly other SS7 parameters depending on the implementation). Basically this means splitting the SS7 traffic over different ASÆs based on GT information. After this, the same as in 1.3.1.1 applies. Loughney (editor) [Page 7] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 1.3.2 Protocol Architecture for Connection-Oriented Transport In this architecture, the SCCP and SUA layers interface in the SGP to associate the two connection sections needed for the connection- oriented data transfer between SEP and ASP. Both connection sections are setup when routing the Connect Request messages from SEP via SGP to ASP or the other way. The routing of the Connect Request message is done in the same way as described in 1.3.1. Further messages for this connection are routed on DPC in the SS7 connection section (MTP routing label), and on IP address in the IP connection section (SCTP header). No other routing information is present in the SCCP or SUA messages themselves. Resources are kept within the SG to forward messages from one section to another and to populate the MTP routing label or SCTP header, based on the destination local reference of these messages (Connect Confirm, Data Transfer, ...) This means that in the SG, two local references are allocated, one 3-byte value used for the SS7 section and one 4 byte value for the IP section. Also a resource containing the connection data for both sections is allocated, and either of the two local references can be used to retrieve this data e.g. for an incoming DT1 or CODT, for example. ******** SS7 *************** IP ******** * SEP *---------* *--------* * * or * * SG * * ASP * * STP * * * * * ******** *************** ******** +------+ +------+ | SUAP | | SUAP | +------+ +------+------+ +------+ | SCCP | | SCCP | SUA | | SUA | +------+ +------+------+ +------+ | MTP3 | | MTP3 | | | | +------| +------+ SCTP | | SCTP | | MTP2 | | MTP2 | | | | +------+ +------+------+ +------+ | L1 | | L1 | IP | | IP | +------+ +------+------+ +------+ | | | | +---------------+ +------------+ SUAP - SCCP/SUA Application Protocol (e.g. - RANAP/RNSAP) STP - SS7 Signaling Transfer Point The above architecture may simplify, in some cases, to carrying SS7 application protocols between two IP based endpoints. In this Loughney (editor) [Page 8] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 scenario, full SG functionality is not needed. This architecture is considered in the next section. 1.3.3 All IP Architecture This architecture can be used to carry a protocol that uses the transport services of SCCP, but is contained with an IP network. This allows extra flexibility in developing networks, especially when interaction between legacy signaling is not needed. The architecture removes the need for signaling gateway functionality. ******** IP ******** * *--------* * * IPSP * * IPSP * * * * * ******** ******** +------+ +------+ | SUAP | | SUAP | +------+ +------+ | SUA | | SUA | +------+ +------+ | SCTP | | SCTP | +------+ +------+ | IP | | IP | +------+ +------+ | | +----------------+ SUAP - SCCP/SUA Application Protocol (e.g. - RANAP/RNSAP) In the case where a collision occurs during initiation, there exist two possible solutions: 1) if there are sufficient resources, both initiations could be accepted; 2) both ASPs should back-off and after some amount of time, later re-establish an initiation. 1.3.4 Generalized Peer-to-Peer Network Architecture Figure 1 shows an example network architecture that can support robust operation and failover. There need to be some management resources at the AS to manage traffic. Loughney (editor) [Page 9] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 *********** * AS1 * * +-----+ * SCTP Associations * |ASP1 +-------------------+ * +-----+ * | *********** * * | * AS3 * * +-----+ * | * +-----+ * * |ASP2 +-----------------------------------------+ASP1 | * * +-----+ * | * +-----+ * * * | * * * +-----+ * | * +-----+ * * |ASP3 | * +--------------------------+ASP2 | * * +-----+ * | | * +-----+ * *********** | | *********** | | *********** | | *********** * AS2 * | | * AS4 * * +-----+ * | | * +-----+ * * |ASP1 +--------------+ +---------------------+ASP1 | * * +-----+ * * +-----+ * * * * * * +-----+ * * +-----+ * * |ASP2 +-----------------------------------------+ASP1 | * * +-----+ * * +-----+ * * * *********** * +-----+ * * |ASP3 | * * +-----+ * * * *********** Figure 1: Generalized Architecture In this example, the Application Servers are shown residing within one logical box, with ASPs located inside. In fact, an AS could be distributed among several hosts. In such a scenario, the host should share state as protection in the case of a failure. Additionally, in a distributed system, one ASP could be registered to more than one AS. This draft should not restrict such systems - though such a case in not specified. 1.3.5 Signaling Gateway Network Architecture When interworking between SS7 and IP domains is needed, the SGP acts as the gateway node between the SS7 network and the IP network. The SGP will transport SCCP-user signaling traffic from the SS7 network to the IP-based signaling nodes (for example IP-resident Databases). The Signaling Gateway can be considered as a group of Application Servers with additional functionality to interface towards an SS7 network. Loughney (editor) [Page 10] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 The SUA protocol should be flexible enough to allow different configurations and transport technology to allow the network operators to meet their operation, management and performance requirements. An ASP may be connected to multiple SGPs (see figure 2). In such a case, a particular SS7 destination may be reachable via more than SG, therefore, more than one route. Given that proper SLS selection, loadsharing, and SG selection based on point code availability is performed at the ASP, it will be necessary for the ASP to maintain the status of each distant SGPs to which it communicates on the basis of the SG through which it may route. Signaling Gateway SCTP Associations +----------+ ************** | SG1 | * AS3 * | ******** | * ******** * | * SGP11+--------------------------------------------+ ASP1 * * | ******** | / * ******** * | ******** | | * ******** * | * SGP12+--------------------------------------------+ ASP2 * * | ******** | \ / | * ******** * +----------+ \ | | * . * \ | | * . * +----------+ \ | | * . * | SG2 | \ | | * . * | ******** | \ | | * ******** * | * SGP21+---------------------------------+-+ * * ASPN * * | ******** | \ * ******** * | ******** | \ ************** | * SGP22+---+--+ \ | ******** | | | \ ************** +----------+ | | \ * AS4 * | | \ * ******** * | +-------------------------------------+ ASP1 * * | * ******** * | * . * | * . * | * * | * ******** * +----------------------------------------+ ASPn * * * ******** * ************** Figure 2: Signaling Gateway Architecture The pair of SGs can either operate as replicated endpoints or as replicated relay points from the SS7 network point of view. Loughney (editor) [Page 11] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Replicated endpoints: the coupling between the SGs and the ASPs when the SGs act as replicated endpoints is an implementation issue. Replicated relay points: in normal circumstances, the path from SEP to ASP will always go via the same SGP when in-sequence-delivery is requested. However, linkset failures may cause MTP to re-route to the other SG. 1.3.6 ASP Fail-over Model and Terminology The SUA protocol supports ASP fail-over functions to support a high availability of transaction processing capability. An Application Server can be considered as a list of all ASPs configured/registered to handle SCCP-user messages within a certain range of routing information, known as a Routing Key. One or more ASPs in the list may normally be active to handle traffic, while others may be inactive but available in the event of failure or unavailability of the active ASP(s). 1.4 Services Provided by the SUA Layer 1.4.1 Support for the transport of SCCP-User Messages The SUA needs to support the transfer of SCCP-user messages. The SUA layer at the SG needs to seamlessly transport the user messages. 1.4.2 SCCP Protocol Class Support Depending upon the SCCP-users supported, the SUA shall support the 4 possible SCCP protocol classes transparently. The SCCP protocol classes are defined as follows: * Protocol class 0 provides unordered transfer of SCCP-user messages in a connectionless manner. * Protocol class 1 allows the SCCP-user to select the in- sequence delivery of SCCP-user messages in a connectionless manner. * Protocol class 2 allows the bi-directional transfer of SCCP- user messages by setting up a temporary or permanent signaling connection. * Protocol class 3 allows the features of protocol class 2 with the inclusion of flow control. Detection of message loss or mis-sequencing is included. Protocol classes 0 and 1 make up the SCCP connectionless service. Protocol classes 2 and 3 make up the SCCP connection-oriented service. Loughney (editor) [Page 12] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 1.4.3 Native Management Functions The SUA layer provides the capability to indicate errors associated with the SUA-protocol messages and to provide notification to local management and the remote peer as is necessary. 1.4.4 Interworking with SCCP Network Management Functions SUA uses the existing ASP management messages for ASP status handling. The interworking with SCCP management consists on the sending of DUNA, DAVA, DAUD, DRST or SCON messages on receipt of SSP, SSA, SST or SSC to the appropriate ASPs. See also chapter 1.4.5. The primitives below are considered to be sent between the SCCP and SUA management functions in the SG to trigger events in the IP and SS7 domain. Generic |Specific | Name |Name |ANSI/ITU Reference ----------+-----------+--------------------------------------------- N-State |Request |ITU-Q.711 Chap 6.3.2.3.2 (Tab 14/Q.711) |Indication |ANSI-T1.112 Chap 2.3.2.3.2 (Tab 8E/T1.112.1) ----------+-----------+--------------------------------------------- N-Pcstate |Indication |ITU-Q.711 Chap 6.3.2.3.3 (Tab 15/Q.711) | |ANSI-T1.112 Chap 2.3.2.3.4 (Tab 8G/T1.112.1) 1.4.5 Support for the management between the SGP and ASP. The SUA layer should provide interworking with SCCP management functions at the SG for seamless inter-operation between the SCN network and the IP network. It should: * Provide an indication to the SCCP-user at an ASP that a SS7 endpoint/peer is unreachable. * Provide an indication to the SCCP-user at an ASP that a SS7 endpoint/peer is reachable. * Provide congestion indication to SCCP-user at an ASP. * Provide the initiation of an audit of SS7 endpoints at the SG. 1.4.6 Relay function For network scalability purposes, the SUA may be enhanced with a relay functionality to determine the next hop SCTP association towards the destination SUA endpoint. The determination of the next hop may be based on Global Title information (e.g. E.164 number), in analogy with SCCP GTT in SS7 networks, modeled in [ITU-T Q.714]. It may also be based on Hostname information, IP address, or pointcode contained in the called party address. Loughney (editor) [Page 13] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 This allows for greater scalability, reliability and flexibility in wide-scale deployments of SUA. The usage of a relay function is a deployment decision. 1.5 Internal Functions Provided in the SUA Layer To perform its addressing and relaying capabilities, the SUA makes use of a Address Mapping Function (AMF). This function is considered part of SUA, but the way it is realized is left implementation / deployment dependent (local tables, DNS (ENUM), LDAP, etc.) The AMF is invoked when a message is received at the incoming interface. The AMF is responsible for resolving the address presented in the incoming SCCP/SUA message to SCTP associations to destinations within the IP network. The AMF will select the appropriate SCTP association based upon routing context / routing key information available. The destination might be the end SUA node or a SUA relay node. The Routing Keys reference an Application Server, which will have one or more ASPs processing traffic for the AS. The availability and status of the ASPs is handled by SUA ASP management messages. Possible SS7 address/routing information that comprise a Routing Key entry includes, for example, OPC, DPC, SIO found in the MTP3 routing label, SCCP subsystem number, or Transaction ID. IP addresses and host names can also be used as Routing Key Information. It is expected that the routing keys be provisioned via a MIB or external process, such as a database. 1.5.1 Address Mapping at the SG Normally, one or more ASPs are active in the AS (i.e., currently processing traffic) but in certain failure and transition cases it is possible that there may not be an active ASP available. The SGP will buffer the message destined for this AS for a time t(r) or until an ASP becomes available. When no ASP becomes available before expiry of t(r), the SGP will flush the buffered messages and initiate the appropriate return or refusal procedures. If there is no match for an incoming message, a default treatment MUST be specified. Possible solutions are to provide a default Application Server to direct all unallocated traffic to a (set of) default ASP(s), or to drop the messages and provide a notification to management. The treatment of unallocated traffic is implementation dependent. 1.5.2 Address Mapping at the ASP Loughney (editor) [Page 14] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 To direct messages to the SS7 network, the ASP MUST perform an address mapping to choose the proper SGP for a given message. This is accomplished by observing the Destination Point Code and other elements of the outgoing message, SS7 network status, SGP availability, and Routing Context configuration tables. A Signaling Gateway may be composed of one or more SGPs. There is, however, no SUA messaging to manage the status of an SGP. Whenever an SCTP association to an SGP exists, it is assumed to be available. Also, every SGP of one SG communicating with one ASP regarding one AS provides identical SS7 connectivity to this ASP. An ASP SHOULD send responses only to that SGP that it received messages from; within the routing context which it is currently active and receiving traffic. The routing context itself is effectively used by the ASP to select the SGP. 1.5.3 Address Mapping Function at a Relay Node The relay function is invoked when: - Routing is on Global Title - Routing is on Hostname - Routing is on SSN+PC or SSN+IP Address and the address presented is not the one of the relay node Translation/resolution of the above address information yields one of the following: - Route on SSN: SCTP association ID towards the destination node, SSN and optionally Routing Context and/or IP address. - Route on GT: SCTP association ID towards next relay node, (new) GT and optionally SSN and/or Routing Context. - Routing on Hostname: SCTP association ID towards next relay node, (new) Hostname and optionally SSN and/or Routing Context. - A local SUA-user (combined relay/end node) To prevent looping, a hop counter is used. The originating end node (be it an SS7 or an IP node) sets the value of the hop counter to the maximum value (15 or less). Each time the relay function is invoked within an intermediate (relay) node, the hop counter MUST be decremented. When the value reaches zero, the return or refusal procedures are invoked with reason "Hop counter violation". 1.5.4 SCTP Stream Mapping The SUA supports SCTP streams. The SG/AS needs to maintain a list of SCTP and SUA-users for mapping purposes. SCCP-users requiring sequenced message transfer need to be sent over a stream supporting sequenced delivery. Loughney (editor) [Page 15] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 SUA MUST use stream 0 for SUA management messages. It is recommended that sequenced delivery be used to preserve the order of management message delivery. Stream selection based on protocol class: - Protocol class 0: SUA SHOULD select an unordered stream. - Protocol class 1: SUA MUST select an ordered stream, based on a sequence parameter given by the upper layer over the primitive interface. - Protocol classes 2 and 3: SUA will select an ordered stream, based on its own source local reference. 1.6 Definition of SUA Boundaries 1.6.1 Definition of the upper boundary The following primitives are supported between the SUA and an SCCP- user (a reference to ITU and ANSI sections where these primitives and corresponding parameters are described, is also given): Generic |Specific | Name |Name |ANSI/ITU Reference ------------+----------+------------------------------------------- N-Connect |Request |ITU-Q.711 Chap 6.1.1.2.2 (Tab 2/Q.711) |Indication|ANSI-T1.112 Chap 2.1.1.2.2 (Tab 2/T1.112.1) |Response | |Confirm | ------------+----------+------------------------------------------- N-Data |Request |ITU-Q.711 Chap 6.1.1.2.3 (Tab 3/Q.711) |Indication|ANSI-T1.112 Chap 2.1.1.2.3 (Tab 3/T1.112.1) ------------+----------+------------------------------------------- N-Expedited |Request |ITU-Q.711 Chap 6.1.1.2.3 (Tab 4/Q.711) Data |Indication|ANSI-T1.112 Chap 2.1.1.2.3 (Tab 4/T1.112.1) ------------+----------+------------------------------------------- N-Reset |Request |ITU-Q.711 Chap 6.1.1.2.3 (Tab 5/Q.711) |Indication|ANSI-T1.112 Chap 2.1.1.2.3 (Tab 5/T1.112.1) |Response | |Confirm | ------------+----------+------------------------------------------- N-Disconnect|Request |ITU-Q.711 Chap 6.1.1.2.4 (Tab 6/Q.711) |Indication|ANSI-T1.112 Chap 2.1.1.2.4 (Tab 6/T1.112.1) ------------+----------+------------------------------------------- N-Inform |Request |ITU-Q.711 Chap 6.1.1.3.1 (Tab 7/Q.711) |Indication|ANSI-T1.112 Chap 2.1.1.2.5 (Tab 6A/T1.112.1) ------------+----------+------------------------------------------- N-Unit Data |Request |ITU-Q.711 Chap 6.2.2.3.1 (Tab 10/Q.711) |Indication|ANSI-T1.112 Chap 2.2.2.3.1 (Tab 8A/T1.112.1) ------------+----------+------------------------------------------- N-Notice |Indication|ITU-Q.711 Chap 6.2.2.3.2 (Tab 11/Q.711) Loughney (editor) [Page 16] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 | |ANSI-T1.112 Chap 2.2.2.3.2 (Tab 8B/T1.112.1) 1.6.2 Definition of the lower boundary The upper layer primitives provided by the SCTP are provided in [SCTP]. 2 Conventions The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when they appear in this document, are to be interpreted as described in [RFC2119]. 3 Protocol Elements The general message format includes a Common Message Header together with a list of zero or more parameters as defined by the Message Type. For forward compatibility, all Message Types may have attached parameters even if none are specified in this version. 3.1 Common Message Header The protocol messages for the SCCP-User Adaptation Protocol requires a message structure which contains a version, message class, message type, message length and message contents. This message header is common among all signaling protocol adaptation layers: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Version | Reserved | Message Class | Message Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Data | Note that the 'data' portion of SUA messages SHALL contain SCCP-User data, not the encapsulated SCCP message. Optional parameters can only occur at most once in an SUA message. 3.1.1 SUA Protocol Version The version field (ver) contains the version of the SUA adaptation layer. The supported versions are: 1 SUA version 1.0 Loughney (editor) [Page 17] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 3.1.2 Message Classes Message Classes 0 SUA Management (MGMT) Message 1 Reserved 2 Signaling Network Management (SNM) Messages 3 ASP State Maintenance (ASPSM) Messages 4 ASP Traffic Maintenance (ASPTM) Messages 5 Reserved 6 Reserved 7 Connectionless Messages 8 Connection-Oriented Messages 9 - 127 Reserved by the IETF 128 - 255 Reserved for IETF-Defined Message Class Extensions 3.1.3 Message Types SUA Management Messages 0 Error (ERR) 1 Notify (NTFY) 2 - 127 Reserved by the IETF 128- 255 Reserved for IETF-Defined Message Class Extensions Signaling Network Management (SNM) Messages 0 Reserved 1 Destination Unavailable (DUNA) 2 Destination Available (DAVA) 3 Destination State Audit (DAUD) 4 Network Congestion (SCON) 5 Reserved 6 Destination Restricted (DRST) 7 - 127 Reserved by the IETF 128 - 255 Reserved for IETF-Defined Message Class Extensions Application Server Process State Maintenance (ASPSM) Messages 0 Reserved 1 ASP Up (UP) 2 ASP Down (DOWN) 3 Heartbeat (BEAT) 4 ASP Up Ack (UP ACK) 5 ASP Down Ack (DOWN ACK) 6 Heartbeat Ack (BEAT ACK) 7 - 127 Reserved by the IETF 128 - 255 Reserved for IETF-Defined Message Class Extensions ASP Traffic Maintenance (ASPTM) Messages Loughney (editor) [Page 18] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 Reserved 1 ASP Active (ACTIVE) 2 ASP Inactive (INACTIVE) 3 ASP Active Ack (ACTIVE ACK) 4 ASP Inactive Ack (INACTIVE ACK) 5 - 127 Reserved by the IETF 128 - 255 Reserved for IETF-Defined Message Class Extensions Connectionless Messages 0 Reserved 1 Connectionless Data Transfer (CLDT) 2 Connectionless Data Response (CLDR) 3 - 127 Reserved by the IETF 128 - 255 Reserved for IETF-Defined Message Class Extensions Connection-Oriented Messages 0 Reserved 1 Connection Request (CORE) 2 Connection Acknowledge (COAK) 3 Connection Refused (COREF) 4 Release Request (RELRE) 5 Release Complete (RELCO) 6 Reset Confirm (RESCO) 7 Reset Request (RESRE) 8 Connection Oriented Data Transfer (CODT) 9 Connection Oriented Data Acknowledge (CODA) 10 Connection Oriented Error (COERR) 11 Inactivity Test (COIT) 12 - 127 Reserved by the IETF 128 - 255 Reserved for IETF-Defined Message Class Extensions 3.1.4 Message Length The Message Length defines the length of the message in octets, including the header and including all padding bytes. 3.1.5 Tag-Length-Value Format SUA messages consist of a Common Header followed by zero or more parameters, as defined by the message type. The Tag-Length-Value (TLV) parameters contained in a message are defined in a Tag-Length- Value format as shown below. Loughney (editor) [Page 19] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Parameter Tag | Parameter Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ \ / Parameter Value / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameter Tag: 16 bits (unsigned integer) Tag field is a 16-bit identifier of the type of parameter. It takes a value of 0 to 65535. Parameter Length: 16 bits (unsigned integer) The Parameter Length field contains the size of the parameter in bytes, including the Parameter Tag, Parameter Length, and Parameter Value fields. The Parameter Length does not include any padding bytes. However, composite parameters will contain all padding bytes, since all parameters contained within this composite parameter will be considered multiples of 4 bytes. Parameter Value: variable-length. The Parameter Value field contains the actual information to be trasnfered in the parameter. The total length of a parameter (including Tag, Parameter Length and Value fields) MUST be a multiple of 4 bytes. If the length of the parameter is not a multiple of 4 bytes, the sender pads the parameter at the end (i.e., after the Parameter Value field) with all zero bytes. The length of the padding is NOT included in the parameter length field. A sender should NEVER pad with more than 3 bytes. The receiver MUST ignore the padding bytes. Implementation note: the use of TLV in principle allows the parameters to be placed in a random order in the message. However, some guidelines should be considered for easy processing in the following order: - Parameters needed to correctly process other message parameters, preferably should precede these parameters (such as Routing Context). - Mandatory parameters preferably SHOULD precede any optional parameters. - The data parameter will normally be the final one in the message. Loughney (editor) [Page 20] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 - The receiver SHOULD accept parameters in any order, except where explicitly mandated. 3.2 SUA Connectionless Messages The following section describes the SUA Connectionless transfer messages and parameter contents. The general message format includes a Common Message Header together with a list of zero or more parameters as defined by the Message Type. All Message Types can have attached parameters. 3.2.1 Connectionless Data Transfer (CLDT) This message transfers data between one SUA to another. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0101 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0102 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Source Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0103 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0003 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Flags Mandatory Source Address Mandatory Destination Address Mandatory Data Mandatory Loughney (editor) [Page 21] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Implementation note: This message covers the following SCCP messages: unitdata (UDT), extended unitdata (XUDT), long unitdata (LUDT). 3.2.2 Connectionless Data Response (CLDR) This message is used as a response message by the peer to report errors in the received CLDT message, when the return on error option is set. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0101 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0106 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SCCP Cause | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0102 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Source Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0103 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0003 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Flags Mandatory SCCP Cause Mandatory Source Address Mandatory Destination Address Mandatory Data Optional Loughney (editor) [Page 22] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Implementation note: This message covers the following SCCP messages: unitdata service (UDTS), extended unitdata service (XUDTS) and long unitdata service (LUDTS). 3.3 Connection Oriented Messages 3.3.1 Connection Oriented Data Transfer (CODT) This message transfers data between one SUA to another for connection-oriented service. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0107 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0003 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Sequence number Mandatory *1 Destination Reference Number Mandatory Data Mandatory NOTE *1: This parameter is not present in case of Expedited Data (ED). Implementation note: This message covers the following SCCP messages: DaTa form 1 (DT1), DaTa form 2 (DT2), Expedited Data (ED). 3.3.2 Connection Oriented Data Acknowledge (CODA) This message is used to acknowledge receipt of data by the peer. This message is used only with protocol class 3. Loughney (editor) [Page 23] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0108 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Receive Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x010A | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Credit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Destination Reference Number Mandatory Receive Sequence number Mandatory *1 Credit Mandatory *1 NOTE *1: Mandatory when representing Data Acknowledgement (AK). Implementation note: This message covers the following SCCP messages: data AcKnowledgement (AK), Expedited data Acknowledgement (EA). 3.3.3 Connection Request (CORE) This message is used for establishing a signaling connection between two peer endpoints. Loughney (editor) [Page 24] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0101 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0104 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0103 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0102 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Source Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x010A | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Credit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0003 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Flags Mandatory Source Reference Number Mandatory Destination Address Mandatory Source Address Optional Credit Mandatory, protocol class 3 only Data Optional Implementation note: This message covers the following SCCP message: Connection Request (CR). 3.3.4 Connection Acknowledge (COAK) Loughney (editor) [Page 25] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 This message is used to acknowledge a connection request from the peer endpoint. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0101 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0104 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x010A | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Credit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0103 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0003 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Flags Mandatory Destination Reference Number Mandatory Source Reference Number Mandatory Credit Mandatory *2 Destination Address Optional *1 Data Optional NOTE *1: Destination Address parameter will be present in case that the received CORE message conveys the Source Address parameter. Loughney (editor) [Page 26] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 NOTE *2: Only applicable for protocol class 3. Implementation note: This message covers the following SCCP message: Connection Confirm (CC). 3.3.5 Connection Refused (COREF) This message is used to refuse a connection request between two peer endpoints. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0106 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SCCP Cause | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0103 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0003 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Destination Reference Number Mandatory SCCP Cause Mandatory Destination Address Optional *1 Data Optional Note *1: Destination Address parameter will be present in case that the received CORE message conveys the Source Address parameter. Implementation note: This message covers the following SCCP message: Connection REFused (CREF). Loughney (editor) [Page 27] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 3.3.6 Release Request (RELRE) This message is used to request a signaling connection between two peer endpoints be released. All associated resources can then be released. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0104 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0106 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SCCP Cause | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0101 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0003 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Destination Reference Number Mandatory Source Reference Number Mandatory SCCP Cause Mandatory Flags Optional Data Optional Implementation note: This message covers the following SCCP message: connection ReLeaSeD (RLSD). 3.3.7 Release Complete (RELCO) Loughney (editor) [Page 28] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 This message is used to acknowledge the release of a signaling connection between two peer endpoints. All associated resources should be released. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0104 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Destination Reference Number Mandatory Source Reference Number Mandatory Implementation note: This message covers the following SCCP message: ReLease Complete (RLC). 3.3.8 Reset Request (RESRE) This message is used to indicate that the sending SCCP/SUA wants to initiate a reset procedure (re-initialization of sequence numbers) to the peer endpoint. Loughney (editor) [Page 29] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0104 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0106 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SCCP Cause | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Destination Reference Number Mandatory Source Reference Number Mandatory SCCP Cause Mandatory Implementation note: This message covers the following SCCP message: ReSet Request (RSR). 3.3.9 Reset Confirm (RESCO) This message is used to confirm the Reset Request. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0104 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Loughney (editor) [Page 30] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Parameters Routing Context Mandatory Destination Reference Number Mandatory Source Reference Number Mandatory Implementation note: This message covers the following SCCP message: ReSet Confirmation (RSC). 3.3.10 Connection Oriented Error (COERR) The COERR message is sent to indicate a protocol data unit error. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0106 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SCCP Cause | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Destination Reference Number Mandatory SCCP Cause Mandatory Implementation note: This message covers the following SCCP message: Protocol Data Unit ERRor (ERR). 3.3.11 Connection Oriented Inactivity Test (COIT) This message is used for auditing the signaling connection state and the consistency of connection data at both ends of the signaling connection. Loughney (editor) [Page 31] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0101 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0104 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0107 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x010A | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Credit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Mandatory Flags Mandatory Source Reference Number Mandatory Destination Reference number Mandatory Sequence number Mandatory *1 Credit Mandatory *1 NOTE *1: Information in these parameter fields reflects those values sent in the last data form 2 or data acknowledgement message. They are ignored if the protocol class indicates class 2. Implementation note: This message covers the following SCCP message: Inactivity Test (IT). 3.4 Signaling Network Management Messages 3.4.1 Destination Unavailable (DUNA) Loughney (editor) [Page 32] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 In the scope of SUA, this message is covered by the PC- or N-state indication passed between SCCP and local SCCP-user. The DUNA message is sent from the SGP or relay node to all concerned ASPs (servicing SCCP-users considered local to the SGP or relay node, see chapter 1.3.1.1), when a destination or SCCP-user has become unreachable. The SUA-User at the ASP is expected to stop traffic to the affected destination or SCCP-user through the SGP or relay node initiating the DUNA. The format for DUNA Message parameters is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0103 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Optional Destination Address Mandatory *1 Info String Optional Note 1: The destination address refers to the node that has become unavailable. When the SSN is included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-STATE primitive. When SSN is not included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-PCSTATE primitive. 3.4.2 Destination Available (DAVA) In the scope of SUA, this message is covered by the PC- and N-state indication passed between SCCP and local SCCP-user. The DAVA message is sent from the SGP or relay node to all concerned ASPs (servicing SCCP-users considered local to the SGP or relay node, see chapter 1.3.1.1) to indicate that a destination (PC or SCCP-user) is now reachable. The ASP SUA-User protocol is expected to resume traffic Loughney (editor) [Page 33] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 to the affected destination through the SGP or relay node initiating the DAVA. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0103 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Optional Destination Address Mandatory *1 Info String Optional Note 1: The destination address refers to the node that has become unavailable. When the SSN is included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-STATE primitive. When SSN is not included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-PCSTATE primitive. 3.4.3 Destination State Audit (DAUD) The DAUD message can be sent from the ASP to the SGP (or relay node) to query the availability state of the routes to an affected destination. A DAUD may be sent periodically after the ASP has received a DUNA, until a DAVA is received. The DAUD can also be sent when an ASP recovers from isolation from the SGP (or relay node). Loughney (editor) [Page 34] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0001 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Optional Destination Address Mandatory *1 Info String Optional Note 1: The destination address refers to the node that has become unavailable. When the SSN is included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-STATE primitive. When SSN is not included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-PCSTATE primitive. 3.4.4 Network Congestion (SCON) The SCON message can be sent from the SGP or relay node to all concerned ASPs to indicate that the congestion level in the SS7 network to a specified destination has changed. Loughney (editor) [Page 35] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0001 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000F | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Congestion Level | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Optional Congestion Level Mandatory Destination Address Mandatory *1 Info String Optional Note 1: The destination address refers to the node that has become unavailable. When the SSN is included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-STATE primitive. When SSN is not included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-PCSTATE primitive. 3.4.5 Destination Restricted (DRST) The DRST message is optionally sent from the SGP to all concerned ASPs to indicate that the SGP has determined that one or more destinations are now restricted from the point of view of the SGP, or in response to a DAUD message if appropriate. The SUA layer at the ASP is expected to send traffic to the affected destination via an alternate SGP of equal priority, but only if such an alternate route exists and is available. If the affected destination is currently considered unavailable by the ASP, the MTP3-User should be informed that traffic to the affected destination can be resumed. In this case, the SUA layer should route the traffic through the SGP initiating the DRST message. Loughney (editor) [Page 36] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 This message is optional for the SGP to send and it is optional for the ASP to act on any information received in the message. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0001 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Destination Address / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Optional Destination Address Mandatory *1 Info String Optional Note 1: The destination address refers to the node that has become unavailable. When the SSN is included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-STATE primitive. When SSN is not included in the Destination Address parameter, the DUNA/DAVA/DRST/SCON message corresponds to the SCCP N-PCSTATE primitive. 3.5 Application Server Process State Maintenance Messages 3.5.1 ASP Up (UP) The ASP UP (UP) message is used to indicate to a remote SUA peer that the Adaptation layer is up and running. Loughney (editor) [Page 37] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000E | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ASP Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0109 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ASP Capabilities | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters ASP Identifier Optional *1 ASP Capabilities Optional Info String Optional Note 1: ASP Identifier MUST be used where the IPSP/SGP cannot identify the ASP by pre-configured address/port number information (e.g., where an ASP is resident on a Host using dynamic address/port number assignment). 3.5.2 ASP Up Ack (UP ACK) The ASP UP Ack message is used to acknowledge an ASP-Up message received from a remote SUA peer. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000E | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ASP Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0109 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ASP Capabilities | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Loughney (editor) [Page 38] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 ASP Identifier Optional *1 ASP Capabilities Optional Info String Optional Note 1: ASP Identifier MUST be used where the IPSP/SGP cannot identify the ASP by pre-configured address/port number information (e.g., where an ASP is resident on a Host using dynamic address/port number assignment). 3.5.3 ASP Down (DOWN) The ASP Down (DOWN) message is used to indicate to a remote SUA peer that the adaptation layer is not running. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Info String Optional 3.5.4 ASP Down Ack (DOWN ACK) The ASP DOWN Ack message is used to acknowledge an ASP-Down message received from a remote SUA peer. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Info String Optional Note: ASP DOWN ACK will always be sent to acknowledge an ASP DOWN. 3.5.5 Heartbeat (BEAT) The Heartbeat message is optionally used to ensure that the SUA peers are still available to each other. The format for the BEAT message is as follows: Loughney (editor) [Page 39] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0009 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Heartbeat Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Heartbeat Data Optional 3.5.6 Heartbeat Ack (BEAT ACK) The Heartbeat ACK message is sent in response to a BEAT message. A peer MUST send a BEAT ACK in response to a BEAT message. It includes all the parameters of the received Heartbeat message, without any change. The format for the BEAT ACK message is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0009 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Heartbeat Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Heartbeat Data Optional 3.6 ASP Traffic Maintenance Messages 3.6.1 ASP Active (ACTIVE) The ASPAC message is sent by an ASP to indicate to a remote SUA peer that it is Active and ready to process signaling traffic for a particular Application Server. The format for the ACTIVE message is as follows: Loughney (editor) [Page 40] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000B | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Traffic Mode Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Traffic Mode Type Mandatory Routing Context Optional Info String Optional 3.6.2 ASP Active Ack (ACTIVE ACK) The ASPAC Ack message is used to acknowledge an ASP-Active message received from a remote SUA peer. The format for the ACTIVE Ack message is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000B | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Traffic Mode Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Traffic Mode Type Mandatory Loughney (editor) [Page 41] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Routing Context Optional Info String Optional The value of the Traffic Mode Type and Routing Context parameters is the same as for the ASP-Active message. The value of the optional Info String parameter is the same as for the ASP-Active message. 3.6.3 ASP Inactive (INACTIVE) The INACTIVE message is sent by an ASP to indicate to a remote SUA peer that it is no longer processing signaling traffic within a particular Application Server. The format for the ASPIA message parameters is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / INFO String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Optional INFO String Optional 3.6.4 ASP Inactive Ack (INACTIVE ACK) The INACTIVE Ack message is used to acknowledge an ASP-Inactive message received from a remote SUA peer. The format for the INACTIVE Ack message is as follows: Loughney (editor) [Page 42] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / INFO String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Routing Context Optional INFO String Optional The value of the optional Info String parameter is the same as for the ASP-Active message. 3.7 SUA Management Messages These messages are used for managing SUA and the representations of the SCCP subsystems in the SUA layer. 3.7.1 Error (ERR) The ERR message is sent between two SUA peers to indicate an error situation. The Data parameter is optional, possibly used for error logging and/or debugging. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000C | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Error Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0007 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Diagnostic Info / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameters Error Code Mandatory Diagnostic Info Optional Loughney (editor) [Page 43] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 3.7.2 Notify (NTFY) The Notify message used to provide an autonomous indication of SUA events to an SUA peer. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000D | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Status | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000E | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ASP Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The NTFY message contains the following parameters: Parameters Status Mandatory ASP Identifier Optional *1 Routing Context Optional Info String Optional Note 1: ASP Identifier MUST be used where the IPSP/SGP cannot identify the ASP by pre-configured address/port number information (e.g., where an ASP is resident on a Host using dynamic address/port number assignment). 3.8 Common Parameters These TLV parameters are common across the different adaptation layers. Parameter Name Parameter ID ============== ============ Reserved 0x0000 Not used in SUA 0x0001 Not used in SUA 0x0002 Data 0x0003 Loughney (editor) [Page 44] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Info String 0x0004 Affected Point Code 0x0005 Routing Context 0x0006 Diagnostic Info 0x0007 Not used in SUA 0x0008 Heartbeat Data 0x0009 Reason 0x000A Traffic Mode Type 0x000B Error Code 0x000C Status 0x000D ASP Identifier 0x000E Congestion Level 0x000F 3.8.1 Not Used Use of Parameter ID 0x0001 in SUA messages is not supported. 3.8.2 Not used Use of Parameter ID 0x0002 in SUA messages is not supported. 3.8.3 Data 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0003 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Data parameter field contains the SS7 SCCP-User application message, for example an INAP/TCAP message. 3.8.4 Info String The INFO String parameter can carry any meaningful 8-BIT ASCII character string along with the message. Length of the INFO String parameter is from 0 to 255 characters. No procedures are presently identified for its use but service providers may use the INFO String for debugging purposes. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0004 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Info String / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Loughney (editor) [Page 45] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 3.8.5 Affected Point Code The Affected Point Code parameter contains one or more Affected Destination Point Codes, each a three-octet parameter to allow for 14-, 16- and 24-bit binary formatted SS7 Point Codes. Affected Point codes that are less than 24-bits, are padded on the left to the 24-bit boundary. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0005 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Mask | Affected PC 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / . . . / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The encoding is shown below for ANSI and ITU Point Code examples. ANSI 24-bit Point Code: 0 1 2 3--> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Mask | Network | Cluster | Member | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |MSB-----------------------------------------LSB| ITU 14-bit Point Code: 0 1 2 3--> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Mask |0 0 0 0 0 0 0 0 0 0|Zone | Region | SP | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |MSB--------------------LSB| It is optional to send an Affected Point Code parameter with more than one Affected PC but it is mandatory to receive it. All the Affected PCs included MUST be within the same Routing Context. Including multiple Affected PCs may be useful when reception of a management message or a linkset event simultaneously affects the availability status of a list of destinations at an SG. Mask: 8-bits Loughney (editor) [Page 46] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 The Mask parameter can be used to identify a contiguous range of Affected Destination Point Codes, independent of the point code format. Identifying a contiguous range of Affected PCs may be useful when reception of an MTP3 management message or a linkset event simultaneously affects the availability status of a series of destinations at an SG. The Mask parameter is an integer representing a bit mask that can be applied to the related Affected PC field. The bit mask identifies how many bits of the Affected PC field are significant and which are effectively "wild-carded". For example, a mask of "8" indicates that the last eight bits of the PC is "wild-carded". For an ANSI 24-bit Affected PC, this is equivalent to signaling that all PCs in an ANSI Cluster are unavailable. A mask of "3" indicates that the last three bits of the PC is "wild-carded". For a 14-bit ITU Affected PC, this is equivalent to signaling that an ITU Region is unavailable. For use in SUA, the mask parameter MUST always be coded zero and there MUST be only a single point code present. 3.8.6 Routing Context 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Routing Context / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Routing Context parameter contains (a list of) 4-byte unsigned integers indexing the Application Server traffic that the sending ASP is configured/registered to receive. There is a one-to-one relationship between an index entry and a Routing Key or AS Name. An Application Server Process may be configured to process traffic for more than one logical Application Server. From the perspective of an ASP, a Routing Context defines a range of signaling traffic that the ASP is currently configured to receive from the SG. Additionally, the Routing Context parameter identifies the SS7 network context for the message, for the purposes of logically separating the signaling traffic between the SGP and the Application Server Process over a common SCTP Association, when needed. An example is where an SGP is logically partitioned to appear as an element in several different national SS7 networks. It implicitly defines the SS7 Point Code format used, the SS7 Network Indicator value and SCCP protocol type/variant/version used within a separate SS7 network. It also defines the network context for the PC and SSN Loughney (editor) [Page 47] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 values. Where an SGP operates in the context of a single SS7 network, or individual SCTP associations are dedicated to each SS7 network context, this functionality is not needed. Where the optional Routing Context parameter is present, it SHOULD be the first parameter in the message as it defines the format and/or interpretation of the parameters containing a PC or SSN value. 3.8.7 Diagnostic Information The Diagnostic Information can be used to convey any information relevant to an error condition, to assist in the identification of the error condition. In the case of an Adaptation Layer Identifier or Traffic Handling Mode, the Diagnostic Information includes the received parameter. In the other cases, the Diagnostic information may be the first 40 bytes of the offending message. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0007 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Diagnostic Information / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.8.8 Not Used Parameter ID 0x0008 is not used in SUA. 3.8.9 Heartbeat Data The sending node defines the Heartbeat Data field contents. It may include a Heartbeat Sequence Number and/or Timestamp, or other implementation specific details. The receiver of a Heartbeat message does not process this field as it is only of significance to the sender. The receiver echoes the content of the Heartbeat Data in a BEAT-Ack message. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0009 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Heartbeat Data / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Loughney (editor) [Page 48] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 The data field can be used to store information in the heartbeat message useful to the sending node (e.g. the data field can contain a time stamp, a sequence number, etc.). 3.8.10 Reason The Reason parameter indicates the reason why the remote SUA adaptation layer is unavailable. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000A | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reason | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Reason: 32-bit (unsigned integer) The valid values for Reason are shown in the following table. 0 Unspecified 1 User Unavailable 2 Management Blocking 3 ASP Fault 3.8.11 Traffic Mode Type The Traffic Mode Type parameter identifies the traffic mode of operation of the ASP within an AS. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000B | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Traffic Mode Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The valid values for Type are shown in the following table. 1 Over-ride 2 Load-share 3 Over-ride (Standby) 4 Loadshare (Standby) Within a Routing Context, Over-ride and Loadshare Types cannot be mixed. The Over-ride value indicates that the ASP is operating in Over-ride mode, and the ASP wishes to take over all traffic for an Application Server (i.e., primary/back-up operation), over-riding any currently active ASP in the AS. In Load-share mode, the ASP Loughney (editor) [Page 49] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 wishes to share in the traffic distribution with any other currently active ASPs. The Standby versions of the Over-ride and Loadshare Types indicate that the ASP is declaring itself ready to accept traffic but leaves it up to the sender as to when the traffic is started. Over-ride (Standby) indicates that the traffic sender continues to use the currently active ASP until it can no longer send/receive traffic (i.e., the currently active ASP transitions to Down or Inactive). At this point the sender may immediately move the ASP to Active and commence traffic. Loadshare (Standby) is similar - the sender continues to loadshare to the current ASPs until it is determined that there is insufficient resources in the Loadshare group. When there are insufficient ASPs, the sender may immediately move the ASP to Active. 3.8.12 Error Code 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag =0x000C | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Error Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Error Code parameter indicates the reason for the Error Message. The Error parameter value can be one of the following values: Invalid Version 0x01 n/a 0x02 Unexpected Message Class 0x03 Invalid Message Type 0x04 Unsupported Traffic Handling Mode 0x05 Unexpected Message 0x06 Protocol Error 0x07 Invalid Routing Context 0x08 Invalid Stream Identifier 0x09 Parameter Field Error 0x0B Unexpected Parameter 0x0C Duplicated Parameter 0x0D Error - ASP Identifier Required 0x0E Error - Invalid ASP Identifier 0x0F Refused - ASP Identifier Required 0x10 The "Invalid Version" error would be sent if a message was received with an invalid or unsupported version. The Error message would contain the supported version in the Common header. The Error message could optionally provide the supported version in the Diagnostic Information area. The "Invalid Routing Context" error would be sent by a SG if an ASP sends a message with an invalid (unconfigured) Routing Context Loughney (editor) [Page 50] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 value. The Error message could optionally provide the invalid Routing Context in the Diagnostic Information area. The "Unexpected Message Class" error would be sent if a message with an unsupported Message Class were received. The "Unexpected Message Type" error would be sent if a message with an unsupported Message Type were received. The "Unsupported Traffic Handling Mode" error would be sent by a SGP if an ASP sends an ASP Active with an unsupported Traffic Handling Mode. An example would be a case in which the SGP did not support load sharing. The "Unexpected Message" error would be sent by an ASP if it received a message that is unexpected in the ASP's current state. The "Protocol Error" error would be sent for any protocol anomaly (i.e. a bogus message). The "Invalid Routing Context" error would be sent by a SGP if the routing context cannot be supported, e.g. not unique. The "Invalid Stream Identifier" error would be sent if a message was received on an unexpected SCTP stream. The "Parameter Field Error" would be sent if a message with a parameter having a wrong length field. The "Unexpected Parameter" error would be sent if a message contains an invalid parameter. The "Duplicated Parameter" error would be sent if a message contains a parameter more than once. To be sent in response to an ASPUP message which does not contain an ASP Id parameter when the SGP requires one. Then, instead of simply adding 8 bytes to ever ASPUP message as proposed, the ASP can go around again a second time with an ASP ID. 3.8.13 Status The Status parameter identifies the type of the status that is being notified and the Status ID. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000D | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Status Type | Status ID | Loughney (editor) [Page 51] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The valid values for Status Type (16 bit unsigned integer) are: 1 Application Server state change (AS_State_Change) 2 Other The Status ID parameter contains more detailed information for the notification, based on the value of the Status Type. If the Status Type is AS_STATE_CHANGE, then the Status ID (16 bit unsigned integer) values are: 1 reserved 2 Application Server Inactive (AS-Inactive) 3 Application Server Active (AS-Active) 4 Application Server Pending (AS-Pending) These notifications are sent from an SGP to an ASP upon a change in status of a particular Application Server. The value reflects the new state of the Application Server. If the Status Type is ôOther", then the following Status Information values are defined: 1 Insufficient ASP resources active in AS 2 Alternate ASP Active These notifications are not based on the SGP reporting the state change of an ASP or AS. In the Insufficient ASP Resources case, the SGP is indicating to an "Inactive" ASP(s) in the AS that another ASP is required to handle the load of the AS (Load-sharing mode). For the Alternate ASP Active case, an ASP is informed when an alternate ASP transitions to the ASP-Active state in Over-ride mode. 3.8.14 ASP Identifier Loughney (editor) [Page 52] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000E | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ASP Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ASP Identifier field: 32-bits (unsigned integer) The ASP Identifier field contains a unique value that is locally significant amoung the ASPs that support an AS. The SGP should save the ASP Identifier to be used, if necessary, with the Notify message (see Section 3.7.2). 3.8.15 Congestion Level 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x000E | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Congestion Level | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Congestion Level field: 8-bits (unsigned integer) The valid values for the Congestion Level parameter range from 0 to 7, where 0 indicates least congested and 7 indicates most congested subsystem. 3.9 SUA-Specific parameters These TLV parameters are specific to the SUA protocol. Parameter Name Parameter ID ============== ============ Flags 0x0101 Source Address 0x0102 Destination Address 0x0103 Source Reference Number 0x0104 Destination Reference Number 0x0105 SCCP Cause 0x0106 Sequence Number 0x0107 Receive Sequence Number 0x0108 ASP Capabilities 0x0109 Credit 0x010A Reserved 0x010B SMI / Subsystem 0x010C Loughney (editor) [Page 53] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Destination/Source Address Sub-Parameters =========================================== Global Title 0x8001 Point Code 0x8002 Subsystem Number 0x8003 IPv4 Address 0x8004 Hostname 0x8005 IPv6 Addresses 0x8006 3.9.1 Flags The Flags parameter is a conglomerate of following parameters, described in ITU-T Recommendation Q.713: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0101 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Seq. Control | Importance | Hop Counter | Protocol Cl. | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Sequence Control (1.1.2/Q.714) Bits 1-5 are coded with the value of the sequence control parameter associated with a group of messages and are chosen so as to ensure proper loadsharing of message groups over SLS values while ensuring that sequence control values within message groups have the sequence control value coded with the same value as the initial message of the message group. Bits 6-8 are spare bits and should be coded zero. Protocol class (3.6/Q.713) Bits 1-2 indicate the protocol class. Value Description 0 Class 0 (connectionless service) 1 Class 1 (connectionless service) 2 Class 2 (connection-oriented service) 3 Class 3 (connection-oriented service) Bit 8 indicates the use of the return on error procedure. Value Description 0x0 No special options 0x1 Return message on error Bits 3-7 are spare and should be coded zero. Loughney (editor) [Page 54] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Hop Counter (3.18/Q.713) The value of the hop counter is decremented with each global title translation, and should be in the range 15 to 1. Importance (3.19/Q.713) Bits 1-3 are coded to indicate the importance of the messages. The values are between 0 and 7, where the value of 0 indicates the least important and 7 indicates the most important. Bits 4-8 are spare bits and should be coded zero. 3.9.2 Source Address 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0102 | Parameter Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Routing Indicator | Address Indicator | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / Address parameter(s) / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Source Address field may contain the SCCP Calling Party Address. See chapters 3.4 and 3.5 of ITU-T Recommendation Q.713. The following combinations of address parameters are valid : - Global Title (e.g. E.164 number) + optional PC and/or SSN, SSN may be zero, when routing is done on Global Title - SSN (non-zero) + optional PC and/or Global Title, when routing is done on PC + SSN. The PC is mandatory in the source address when sending from SGP to ASP, and in the destination address when sending from ASP to SGP to reach the SS7 SEP. - Hostname + optional SSN, when routing is done by Hostname - SSN (non-zero) and optional IP address (IPv4 or IPv6) when routing is done on IP address + SSN 3.9.2.1 Routing Indicator The following values are valid for the routing indicator : Reserved 0 Route on Global Title 1 Route on SSN + PC 2 Loughney (editor) [Page 55] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Route on Hostname 3 Route on SSN + IP Address 4 The routing indicator determines which address parameters need to be present in the address parameters field. 3.9.2.2 Address Indicator This parameter is needed for interworking with SS7 networks. The address indicator specifies what address parameters are actually received in the SCCP address from the SS7 network, or are to be populated in the SCCP address when the message is sent into the SS7 network. The value of the routing indicator needs to be taken into account. The address indicator is coded as follows: Bit 1 is used to indicate inclusion of the SSN 0 Do not include SSN when optional 1 Include SSN Bit 2 is used to indicate inclusion of the PC 0 Do not include PC, regardless of the routing indicator value 1 Include PC Bit 3 is used to indicate inclusion of the Global Title 0 Do not include GT when optional (routing indicator /= 1) 1 Include GT Bits 4-8 are spare and should be coded zero. 3.9.2.3 Global Title 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x8001 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | No. Digits | Trans. type | Num. Plan | Nature of Add | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Global Title Digits | / / | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Number of Digits: Loughney (editor) [Page 56] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 This is the number of digits contained in the Global Title. Translation type: 0 Unknown 1 - 63 International services 64 - 127 Spare 128 û 254 National network specific 255 Reserved Numbering Plan: 0 unknown 1 ISDN/telephony numbering plan (Recommendations E.163 and E.164) 2 generic numbering plan 3 data numbering plan (Recommendation X.121) 4 telex numbering plan (Recommendation F.69) 5 maritime mobile numbering plan (Recommendations E.210, E.211) 6 land mobile numbering plan (Recommendation E.212) 7 ISDN/mobile numbering plan (Recommendation E.214) 8 - 13 spare 14 private network or network-specific numbering plan 15 - 126 spare 127 reserved. Nature of Address: 0 unknown 1 subscriber number 2 reserved for national use 3 national significant number 4 international number 5 - 255 Spare Global Title: Octets contain a number of address signals and possibly filler as shown: Loughney (editor) [Page 57] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |2 addr.|1 addr.|4 addr.|3 addr.|6 addr.|5 addr.|8 addr.|7 addr.| | sig. | sig. | sig. | sig. | sig. | sig. | sig. | sig. | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ............. |filler |N addr.| filler | | |if req | sig. | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ All filler bits MUST be set to 0. Address signals to be coded as defined in ITU-T Q.713 Section 3.4.2.3.1. The actual Global Title format to be used for interworking with the SS7 network is defined by the network ID, or is implicitly understood if the SGP only operates in one SS7 network partition. The formats are defined in chapter 3.4.2.3 of Q.713. The following conversions of the Translation Type, Numbering Plan and Nature of Address elements apply: 1) SS7 network uses GTI = 0001 Nature of Address is ignored. It is implicitly assumed that Translation Type = Unknown and Numbering Plan = E.164 (value 1). 2) SS7 network uses GTI = 0010 This is most commonly used in North American networks. The Translation Type implicitly determines Nature of Address and Numbering Plan. This data can be configured in the SG. The number of digits is always even and determined by the SCCP address length. 3) SS7 network uses GTI = 0011 Numbering Plan and Translation Type are taken over. It is implicitly assumed that the Nature of Address = Unknown. 4) SS7 network uses GTI = 0100 This format is used in international networks and most commonly in networks outside North America. All information to populate the source address is present in the SCCP Address. Loughney (editor) [Page 58] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 3.9.2.4 Point Code 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x8002 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Point Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ See chapter 3.2.5 Affected Point Code for the layout of the Point Code field. 3.9.2.5 Subsystem Number 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x8003 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | spare | SSN value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The internationally standardized SSN values are described in chapter 3.4.2.2 of Q.713. 3.9.2.6 IP Addresses The IP address formats can use different tags. It should be noted that if the source address is in a certain IP version, the destination address should also be in the same IP version. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x8004/0x8006 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 or IPv6 Address | / / | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Note: The tag value 0x8004 is for an IPv4 address and 0x8006 is for IPv6. Loughney (editor) [Page 59] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 3.9.2.7 Hostname 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x8005 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Host Name | / / | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ If the type of address is Host Name, then the labels in the host name have to be reversed to obtain an efficient Host Name encoding form for the Global title translation function. hostname: zzzz.yyy....edc.ab should be transformed to HTname : ab.edc....yyy.zzzz The labels of the Host Name are then encoded using the encoding rules of the labels described in [IDNS]. The end of the Host name is indicated by 0x00. Example: hostname = www.reindael.security.org First the name has to be reverse to have the gTLD on the left side. Global Title name: org.security.reindael.www Then the result of applying the rules of the iDNS is: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ x | 3 | O | R | G | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +4 | 8 | S | E | C | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +8 | U | R | I | T | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +12| Y | 8 | R | E | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +16| I | N | D | A | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +20| E | L | 3 | W | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +24| W | W | 00 | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Loughney (editor) [Page 60] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 3.9.3 Destination Address 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0103 | Parameter Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Routing Indicator | Address Indicator | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / address parameter(s) / \ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The format of this parameter is identical to the Source Address parameter. 3.9.4 Source Reference Number 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0104 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The source reference number is a 4 octet long integer. This is allocated by the source SUA instance. 3.9.5 Destination Reference Number 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0105 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Reference Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The destination reference number is a 4 octet long integer. This is allocated by the destination SUA instance. 3.9.6 SCCP Cause Loughney (editor) [Page 61] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0106 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Spare | Cause Type | Cause Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This parameter bundles the SCCP parameters Release cause, Return cause, Reset cause, Error cause and Refusal cause. Cause Type can have the following values: Return Cause 0x1 Refusal Cause 0x2 Release Cause 0x3 Reset Cause 0x4 Error Cause 0x5 Cause Value contains the specific cause value. Below gives examples for ITU SCCP values. ANSI references can be found in ANSI T1.112.3 Cause value in Correspondence with Reference SUA message SCCP parameter ------------------ ----------------- --------- CLDR Return Cause ITU-T Q.713 Chap 3.12 COREF Refusal Cause ITU-T Q.713 Chap 3.15 RELRE Release Cause ITU-T Q.713 Chap 3.11 RESRE Reset Cause ITU-T Q.713 Chap 3.13 ERR Error Cause ITU-T Q.713 Chap 3.14 3.9.7 Sequence Number 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0107 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Spare | Rec Seq Num|M| Sent Seq Num | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This parameter is used to indicate whether ômoreö data will follow in subsequent CODT messages, and/or to number each CODT message sequentially for the purpose of flow control. It contains the received as well as the sent sequence number, P(R) and P(S) in Q.713, chapters 3.7 and 3.9. As such it can also be used to acknowledge the receipt of data transfers from the peer in case of protocol class 3. Sent Sequence Number is one octet and is coded as follows: Loughney (editor) [Page 62] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Bits 2-8 are used to indicate the Send Sequence Number P(S). Bit 1 (LSB) of octet 1 is spare. Received Sequence Number is one octet, and is coded as follows: Bits 2-8 are used to indicate the Received Sequence Number P(R). Bit 1 (LSB) is used for the more data indication, as follows: 0 no more data 1 more data 3.9.8 Receive Sequence Number 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0108 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | spare | Rec Seq Num | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This parameter is used exclusively for protocol class 3 in the data acknowledgment message to indicate the lower edge of the receiving window. See Q.713, chapter 3.8. It is a 1 octet long integer coded as follows: Bits 8-2 are used to indicate the Receive Sequence Number P(R). Bit 1 is spare. 3.9.9 ASP Capabilities This parameter is used so that the ASP can report its capabilities regarding SUA for supporting different protocol classes and interworking scenarios. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x0109 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | spare |0 0 0 0|a|b|c|d| Interworking | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Flags a - Protocol Class 3 b - Protocol Class 2 Loughney (editor) [Page 63] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 c - Protocol Class 1 d - Protocol Class 0 It is mandatory to support at least Protocol Class 0. Interworking Values 0x0 indicates no interworking with SS7 Networks. 0x1 indicates IP Signaling Endpoint (ASP), interworking with SS7 networks. 0x2 indicates Signaling Gateway. 0x3 indicates relay node support. 3.9.10 Credit 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x010A | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Credit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The length of the credit field is is one octet. See ITU-T Q.713 Chapter 3.10. The parameter is used for protocol class 3 exclusively. 3.9.11 SMI / Subsystem 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tag = 0x010C | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SMI | Spare | SSN | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Subsystem Number (SSN) is one octet. Subsystem Multiplicity Indicator (SMI) can have the following values: 0x00 Reserved 0x01 Replicated 0x02 Solitary 0x03 Unknown 4 Procedures Loughney (editor) [Page 64] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 The SUA layer needs to respond to various local primitives it receives from other layers as well as the messages that it receives from the peer SUA layers. This section describes the SUA procedures in response to these events. 4.1 SCCP û SUA Interworking at the SG On the SG, the SCCP routing or interworking function determines that the message is sent to an AS via the SUA stack, based on information in the incoming message. The SUA Address Mapping Function identifies the appropriate Application Server (AS) and selects an active ASP from the list of ASPs servicing this AS. The appropriate ASP can be determined based on the routing information in the incoming message, local load sharing information, etc. The appropriate SUA message is then constructed and sent to the appropriate endpoint, via the correct SCTP association and stream. The SGP MUST take care of any segmentation / reassembly issues at the border of the SS7 and IP networks. The IPSP may not have any knowledge about the requirements regarding the maximum supported message length of the SS7 network to which it is sending. However, since there is in principle no limit to the use of the more indicator in SS7 networks, there is still need for connection- oriented segmentation / reassembly procedures in the IPSP as well. If a SGP is operated in mated pair configuration, and it receives a non-first XUDT segment for which no reassembly process exists, it should pass on this segment to it's mate; if the segment was already received from the mated SGP or if no mated SGP is available, the return on error procedures is invoked. 4.1.1 Connection Oriented Procedures On receipt of a CR message from the SS7 network, a first connection section is established between the SGP and SS7 originating node. A second connection section is to be setup between the SGP and the appropriate ASP, determined by the SUA outgoing mapping function. Local resources and source local reference numbers are allocated to keep/retrieve the required address information and the connection state to format and route subsequent messages for the connection based on reference numbers only. The existing SCCP procedures MAY be deployed at the SGP to perform this coupling. The same applies for a CORE message received from the IP network, destined for an SS7 node. After allocating the necessary resources, the SUA incoming mapping function formats the appropriate SCCP message and passes it on to SCCP routing for further processing (sending into the SS7 network). Loughney (editor) [Page 65] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 The SGP MUST take care of any segmentation / reassembly issues at the border of the SS7 and IP networks. The IPSP may not have any knowledge about the requirements regarding the maximum supported message length of the SS7 network to which it is sending. However, since there is in principle no limit to the use of the more indicator in SS7 networks, there is still need for connection- oriented segmentation / reassembly procedures in the IPSP as well. 4.1.2 Connectionless Procedures The existing SCCP routing functions may be enhanced to support interworking with the SUA layer. The function of SUA can be limited to outgoing mapping (formatting of the CLDT or CLDR message) and selection of the correct SCTP association (ASP) and stream. For the direction ASP to SG, the SUA incoming mapping formats the appropriate SCCP message (UDT(S), XUDT(S) or LUDT(S)) and passes it on to SCCP routing for further processing. 4.1.3 SS7 Signaling Network Management Procedures When an SCCP Subsystem Management (SCMG) message is received from the SS7 network, the SGP needs to determine whether there are concerned Application Servers interested in subsystem status changes. The SUA management function is informed with the N-State indication primitive upon which it formats and transfers the applicable SNM message to the list of concerned ASPs using stream ID "0". When MTP-3 Management indications are received (MTP-PAUSE, MTP- RESUME, MTP-STATUS), SCCP Subsystem Management determines whether there are concerned local SCCP-users. When these local SCCP-users are in fact Application Servers, serviced by ASPs, SUA management is informed with the PC-State indication primitive upon which it formats and transfers the applicable SNM message (DUNA, DAVA, DRST or SCON) to the list of concerned ASPs using stream ID "0". If an ASP receives a DUNA, DRST or SCON from a SGP, the SUA layer at the ASP is expected to send traffic to the affected destination via an alternate SGP of equal priority, but only if such an alternate route exists and is available. The local ASP SHOULD maintain the status of the possible routes to the peer endpoint in the SS7 network. By maintaining the status of the possible routes, the ASP can determine if the remote peer is unavailable. When the DAUD message is received at the SGP from an ASP, the SGP checks the status of the specified SS7 destination and returns DAVA, DUNA, DRST or SCON depending on the result of the check. The SGP initiates SST (Subsystem Status Test) procedures by following the SCCP procedures described in Q.714; the receipt of a DAUD message does not trigger these. Loughney (editor) [Page 66] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 SCCP Subsystem Management procedures may also be triggered in case of AS state changes, see chapter 4.4.1.2. 4.2 Primitives received from the local SUA-user These support the SUA transport of SCCP-User/SCCP boundary primitives. The same services as supported by SCCP (connectionless and connection-oriented) are to be provided by SUA. The SCCP-users at the SGP should be able to use the same primitive interface to SCCP/SUA without any changes. The SCCP-SUA interworking function takes care of selecting the appropriate stack. The SUA needs to setup and maintain the appropriate SCTP association to the selected endpoint. SUA also manages the usage of SCTP streams. The address information passed by the SUA-user at an ASP MUST contain either: - A valid SS7 address to reach a destination in the SS7 network via the appropriate SCTP association to a SG. - A valid IP address/hostname to reach another ASP in the IP network via the appropriate SCTP association. 4.3 Layer Management Procedures On receiving primitives from the local Layer Management, the SUA layer will take the requested action and provide a response to Layer Management. An M-SCTP-ESTABLISH request from Layer Management will initiate the establishment of an SCTP association. An M-SCTP-ESTABLISH confirm will be sent to Layer Management when the initiated association set- up is complete. An M-SCTP-ESTABLISH indication is sent upon successful completion of an incoming SCTP association set-up from a peer SUA node. An M-SCTP-RELEASE request from Layer Management initiates the teardown of an SCTP association. An M-SCTP-RELEASE confirm is sent to Layer Management when the association teardown is complete. An M- SCTP-RELEASE indication is sent to Layer Management upon successful teardown of an SCTP association initiated by a peer SUA. An M-SCTP-STATUS request supports a Layer Management query of the local status of a particular SCTP association. The SUA responds with the association status in an M-SCTP-STATUS confirm. No peer SUA protocol is invoked. An M-ASP-STATUS request supports a Layer Management query of the status of a particular local or remote ASP. The SUA responds with an M-ASP-STATUS confirm. No peer SUA protocol is invoked. Loughney (editor) [Page 67] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 An M-AS-STATUS request supports a Layer Management query of the status of a particular AS. The SUA responds with an M-AS-STATUS confirm. No peer SUA protocol is invoked. M-ASP-UP, -DOWN, -ACTIVE and ûINACTIVE request primitives allow Layer Management at an IPSP to force state changes. Upon successful completion, a corresponding confirm primitive is issued by SUA to the Layer Management. If the invocation is unsuccessful, an Error indication is provided. SUA Management informs layer Management about AS/ASP state changes with the corresponding indications. It is also informed of received NTFY or ERR messages, see chapter 4.4.3. 4.4 SUA Management Procedures This functionality comprises the handling of AS/ASP state and traffic management messages, SUA peer management messages, SCTP notifications and the interface with local Layer Management. These procedures support the SUA management of SCTP Associations and ASP paths between SGs and ASPs. 4.4.1 AS and ASP State and Traffic Management The SUA layer on each IPSP (e.g. SG) needs to maintain the state of each connected IPSP (e.g. ASP), as a way to manage the traffic to these IPSPs and the (logical) ASs they service. In particular at a SG, the state of each connected ASP is needed as input to the SGs routing function. 4.4.1.1 ASP States The state of each ASP is maintained in the SUA layer at the controlling AS. The state of an ASP changes due to events. The events include: - ASP Management messages (ASP-Up, ASP-Down, ASP-Active, ASP- Inactive). - SCTP Communication Down Notification (SCTP CDI). The state of the ASP within each AS is important in particular for the routing function at the SG, to direct traffic for a specific routing key (AS) to the appropriate ASP. At an ASP, if it is connected to a set of redundant SGs, this set can also be seen as an AS handling all traffic destined for the SS7 network. The ASP state transition diagram is shown in Figure 4. The possible states of an ASP are: Loughney (editor) [Page 68] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 ASP-DOWN: The Application Server Process is unavailable. Initially all ASPs will be in this state. ASP-UP: The Application Server Process is available but application traffic is not possible. The ASP can only handle management messages. ASP-ACTIVE: The Application Server Process is available and application traffic is possible. Whether traffic will be directed to this ASP depends on the Traffic Mode Type (over-ride, loadshare with or without Standby option). +-------------+ | ASP-ACTIVE | +----------------------| or | | +------| ASP-STANDBY*| | AS | +-------------+ | Override | ^ | | | ASP | | ASP | | Active | | Inactive | | | v | | +-------------+ | +------| | | | ASP-INACTIVE| | +-------------+ | ^ | ASP Down | ASP | | ASP Down / SCTP CDI | Up | | SCTP CDI | | v | +-------------+ | | | +--------------------->| ASP-DOWN | | | +-------------+ * Note: ASP-ACTIVE and ASP-STANDBY differ only in whether the ASP is currently receiving Data traffic within the AS. Figure 4: ASP State Transition Diagram SCTP CDI: The local SCTP layer's SHUTDOWN COMPLETE notification or COMMUNICATION LOST notification. The shutdown of an SCTP association may have been requested by local Layer Management, see chapter 4.3. Local Layer Management 4.4.1.2 AS States The AS is configured in the IPSP as a logical entity to handle traffic for a specific (unique) routing key. The state of the AS is maintained in the SUA layer, and can change due to following events: Loughney (editor) [Page 69] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 - ASP state changes: when the first ASP within an AS goes UP or ACTIVE, or when the last ASP within an AS goes DOWN or INACTIVE - Recovery Timer expiry The possible states of an AS are: AS-DOWN: The Application Server is unavailable. This state implies that all related ASPs are in the ASP-DOWN state for this AS. Initially the AS will be in this state. AS-UP: The Application Server is available but no application traffic is possible (i.e. one or more related ASPs are in the ASP-UP state, but none in the ASP-ACTIVE state). AS-ACTIVE: The Application Server is available and application traffic is possible. This state implies that at least one ASP is in the ASP-ACTIVE state. AS-PENDING: An active ASP has transitioned from active to inactive or down and it was the last remaining active ASP in the AS. A recovery timer T(r) will be started and all incoming SCN messages will be queued by the SG. If an ASP becomes active before T(r) expires, the AS will move to AS-ACTIVE state and all the queued messages will be sent to the active ASP. If T(r) expires before an ASP becomes active, the SGP stops queuing messages and discards all previously queued messages. The AS will move to AS-UP if at least one ASP is in ASP-UP state, otherwise it will move to AS-DOWN state. Loughney (editor) [Page 70] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 +----------+ one ASP trans to ASP-ACTIVE +-------------+ | |---------------------------->| | | AS-UP | | AS-ACTIVE | | |<--- | | +----------+ \ +-------------+ ^ | \ Tr Expiry, ^ | | | \ at least one | | | | \ ASP in ASP-INACTIVE | | | | \ | | | | \ | | | | \ | | one ASP | | all ASP \ one ASP | | Last ACT. trans | | trans to \ trans to | | ASP trans to ASP- | | ASP-DOWN -------\ ASP-ACTIVE| | to ASP- INACTIVE| | \ | | INACTIVE | | \ | | or ASP- | | \ | | DOWN | | \ | | | v \ | v +----------+ \ +-------------+ | | --| | | AS-DOWN | | AS-PENDING | | | | (queuing) | | |<----------------------------| | +----------+ Tr Expiry no ASP +-------------+ in ASP-INACTIVEstate Tr = Recovery Timer Figure 5: AS State Transition Diagram The SGP maintains the availability of the ASs, and will need to issue the correct SCCP management message (where applicable) to the SS7 node(s). When an AS transitions to the UP or DOWN state, and it is the only (or last) one handling traffic for a certain SSN, an SSP message is broadcast to the concerned remote SCCP-users in the SS7 network. When an AS transitions to the ACTIVE state, and it is the first one handling traffic for a certain SSN, an SSA message is broadcast to the concerned remote SCCP-users in the SS7 network. 4.4.2 AS/ASP Management procedures Once an SCTP association is established between two IPSPs, one (or both) side(s) might issue an ASP-UP message. 4.4.2.1 ASP-Up Loughney (editor) [Page 71] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 An ASP sends an ASP-UP to each communication partner. When the ASP- UP message is received, the receiving IPSP can react in three different ways: - Mark the remote ASP Inactive and reply with an ASP-UP Ack message in acknowledgement to every received ASP-UP, even if the ASP is already marked as Inactive. - If for any local reason (e.g. management lock-out) the IPSP cannot respond with an ASP-UP Ack, it responds with an ASP- DOWN Ack message. - If an unknown version is received with the ASP-UP message, the receiving end MUST respond with an Error message with Error Code ôInvalid Versionö. The version field in the common header will indicate to the sender which version(s) the receiving node supports. This is useful when protocol version upgrades are being performed. A node with the newer version should support the older versions as well to fallback upon in a subsequent ASP-UP message. If the ASP does not receive any of the above reactions, the ASP may resend ASP-Up messages until it receives a response. The ASP MUST wait for the ASP-UP Ack message before sending any other messages. If the remote peer receives any other SUA messages from an ASP, before an ASP-UP is received and acknowledged, the message should be discarded. If the ASP Up message contains an ASP Identifier, the SGP should save the ASP Identifier for that ASP, to be used in any Notify messages, which are sent indicating a change in the state of the ASP. 4.4.2.2 ASP-Down The IPSP will mark an ASP as down if one of the following events occur: - An ASP Down (DOWN) message is received from the ASP. - The ASP is locked by local Layer Management. The IPSP sends an ASP DOWN Ack message in response to a received ASP-DOWN message from the ASP even if the ASP is already marked as Down. The IPSP will send an ASP DOWN message whenever it wants to take down an ASP. Since it is possible for ASP DOWN and ASP DOWN Ack messages to be lost (for example, during a node failover), the IPSP can send ASP DOWN messages repeatedly until the path comes down (i.e. until it receives a ASP-DOWN message from the remote peer or the SCTP association goes down). Loughney (editor) [Page 72] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 4.4.2.3 ASP-Active When an ASP is ready to start processing traffic, it sends an ASP- ACTIVE message to the remote peer. When an ASP-ACTIVE message is received, the remote peer responds with an ASP-ACTIVE Ack. The ASP cannot send any other messages until after the ASP-ACTIVE Ack is received. If the ASP-ACTIVE Ack is not received within a certain time, the ASP may resend the ASP-ACTIVE message. The ASP-ACTIVE message optionally contains a list of one or more Routing Contexts, indicating which Application Servers the ASP is joining. If no Routing Contexts are present, then local configuration data is used to determine to which Application Server(s) the ASP belongs. The Traffic Mode Type parameter in the ASP-ACTIVE message indicates the traffic handling mode used in a particular Application Server, either Over-ride, Over-ride (Standby), Load-share or Load-share (Standby). If the remote peer determines that the mode indicated in an ASP-ACTIVE is incompatible with the mode currently used in the AS, the remote peer responds with an Error message indicating "Invalid Traffic Handling Mode". In the Over-ride mode, reception of an ASP-ACTIVE message at a remote peer causes the all traffic for the AS to be sent to the ASP that sent the ASP-ACTIVE. All previously active ASPs in the AS are now considered Inactive and will no longer receive traffic for that particular AS. The remote peer sends a Notify (Alternate ASP- Active) to the previously active ASP in the AS, after stopping all traffic to that ASP. All existing connections/transactions with the previously active ASP should be terminated however. In the Over-ride (Standby) mode, the actions are the same with the exception that the traffic is not started to the ASP until the previously active ASP transitions to the "Inactive or "Down" state. At this point the ASP that sent the Over-Ride (Standby) ASP-ACTIVE message takes over the traffic. No Notify messages are needed. In the Load-share mode, reception of an ASP-ACTIVE message causes the redistribution of traffic to the ASP sending the ASP-ACTIVE, in addition to all the other ASPs that are currently active in the AS. The algorithm at the SGP for load-sharing traffic within an AS to all the active ASPs is implementation dependent. All ASPs marked for load sharing should be able to handle any traffic within the AS, to accommodate any potential fail-over or re-balancing of the offered load. In the Load-share (Standby) mode, the actions are the same as the Load-share mode, with the exception that the traffic is not started to the ASP until the remote peer determines that additional resources are needed to service the AS. When needed, the ASP that Loughney (editor) [Page 73] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 sent the Loadshare (Standby) ASP-ACTIVE message is taken up in the loadsharing scheme and traffic is started. No Notify messages are needed to be sent. A node that receives an ASP-ACTIVE with an incorrect Traffic Mode Type for a particular Routing Context will respond with an Error Message with Error Cause ôInvalid Traffic Handling Modeö. A node that receives an unknown Routing Context value responds with an Error message with Error Cause ôInvalid Routing Contextö. 4.4.2.4 ASP-Inactive When an ASP wishes to withdraw from handling traffic, it sends an ASP-INACTIVE to the applicable remote peers, specifying the AS (Routing Context) from which it is withdrawing. If the ASP is withdrawing from more than one AS, then the ASP issues either multiple ASP-INACTIVE messages, if multiple SCTP associations exist to the remote ASPs; or a single ASP-INACTIVE message containing multiple Routing Contexts. The ASP could have been in one of two modes, Over-ride or Load- sharing. In the Over-ride mode, the ASP that sent the ASP-INACTIVE is marked as Inactive. No further traffic is sent from and to the ASP marked Inactive. The remote peer now should notify the remaining ASPs of situation. In the Load-sharing mode, the peer marks the ASP as Inactive and re- allocates the traffic to the remaining active ASPs. The load-sharing mechanism used is outside of the scope of SUA. If there are insufficient resources, a NTFY (Insufficient ASPs) may be sent to all inactive ASPs within the AS. If a Loadshare (Standby) ASP is available, it may be now immediately included in the loadshare group and a Notify message MUST not be sent. An ASP-INACTIVE Ack message is sent to the ASP after all traffic is halted. In the case when no other ASPs are active or standby in the Application Server, the remote peer should send a NTFY (AS-Pending) to all inactive ASPs of the AS. The remote peer then either discards all incoming messages for the AS or starts buffering the incoming messages for T(r) seconds, after which messages will be discarded. T(r) is configurable by the network operator. If the remote peer receives an ASP-ACTIVE from an ASP in the AS before expiry of T(r), the buffered traffic is directed to the ASP and the timer is cancelled. If T(r) expires, the AS is moved to the "Down" state. 4.4.3 SUA peer management messages 4.4.3.1 Notify Loughney (editor) [Page 74] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 A NTFY message reflecting a change in the AS state MUST be sent to all ASPs in the AS, except those in the ASP-DOWN state, with appropriate Status Type/ID and ASP Identifier of the failed ASP. The Notify message MUST be sent after any ASP State or Traffic Management acknowledgement messages (e.g., ASP Up Ack, ASP Down Ack, ASP Active Ack, or ASP Inactive Ack). In the case where a NTFY (AS-Pending) message is sent by an SGP that now has no active ASPs to service the traffic, or a NTFY (Insufficient ASPs) is sent in the Loadshare mode, the NTFY does not explicitly force the ASP(s) receiving the message to become active. The ASPs remain in control of what (and when) action is taken. 4.4.3.2 Error The ERR message is used to signal invalid protocol behavior. 4.4.4 Heartbeat procedure The optional Heartbeat message may be sent to query the status of the remote peer. It is optional to send, but mandatory to acknowledge. It MAY be used when operating over transport layers that do not have their own heartbeat mechanism for detecting loss of the transport association (i.e., other than SCTP). After an ASP or IPSP has received an ASP Up Ack from an SUA peer in response to an ASP Up message, either M3UA peer MAY optionally send Heartbeat messages periodically, subject to a provisionable timer T(beat). Upon receiving a Heartbeat message, the SUA peer MUST respond with a Heartbeat ACK message. If no Heartbeat Ack message (or any other SUA message) is received from the peer within 2*T(beat), the remote peer is considered unavailable. Transmission of Heartbeat messages is stopped and the signaling process SHOULD attempt to re-establish communication, if it is configured as the client for the disconnected M3UA peer. The data field can be used to store information in the heartbeat message useful to the sending node (e.g. the data field can contain a time stamp, a sequence number, etc.). The data field MUST be echoed back unchanged in the related Heartbeat Ack message. The contents/format of the Heartbeat Data parameter is implementation- dependent and only of local interest to the original sender. The ASP sender, upon examining the contents of the returned Heartbeat Ack message, MAY choose to consider the remote M3UA peer as unavailable. Note: Heartbeat related events are not shown in the "ASP state transition diagram". Loughney (editor) [Page 75] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 5 Examples of SUA Procedures The following sequence charts overview the procedures of SUA. These are meant as examples, they do not, in and of themselves, impose additional requirements upon an instance of SUA. 5.1 SG Architecture The sequences below outline logical steps for a variety of scenarios within a SG architecture. Please note that these scenarios cover a Primary/Backup configuration. Where there is a load-sharing configuration then the SGP can declare availability when 1 ASP issues ASPAC but can only declare unavailability when all ASPs have issued ASPIA. 5.1.1 Establishment of SUA connectivity The following is established before SUA/SCCP traffic can flow. Each node is configured (via MIB, for example) with the connections that need to be setup. ASP-a1 ASP-a2 SG SEP (Primary) (Backup) |------Establish SCTP Association------| |--Estab. SCTP Ass--| |--Align SS7 link---| Each ASP declares to the SGP that it is running. +----------------ASP Up----------------> <--------------ASP Up Ack--------------+ +------ASP Up-------> <---ASP Up Ack------+ The Primary ASP declares to the SGP that it is active. The SGP notifies all ASPs. +-------------ASP Active---------------> <----------ASP Active Ack--------------+ <----------NTFY (ASP Active)-----------+ <-NTFY (ASP Active)-+ The SGP declares the availability of the signaling user on ASP-a1 to the SEP. The SGP has been configured (via a MIB) that the SEP is concerned about its signaling users. The SGs SS7 address is presented in the SSA, i.e. the SGP represents the availability of ASP-a1 to the SEP. Loughney (editor) [Page 76] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 +--------SSA--------> The SEP declares its availability to the SGP since the SGP appears within its concerned list. Similarly, the SGP informs the active ASP of the availability of the SEP as dictated by SGs concerned list. N.B. The SGP maps the SS7 address of the SEP to an IP address that the SGP knows ASP-a1 will understand. <--------SSA--------+ <-----------------DAVA-----------------+ Traffic can now flow. A connectionless flow is shown for simplicity. Nevertheless, the SGP is responsible for mapping IP to SS7 addresses and vice-versa. Only the Routing Context for ASP-a1 persists from ASP-a1 to SEP. +-----------------CLDT-----------------> +--------UDT--------> 5.1.2 Failover scenarios The following sequences address failover of SEP and ASP 5.1.2.1 SEP Failover The SEP knows that the SGP is 'concerned' about its availability. Similarly, the SGP knows that ASP-a1 is concerned about the SEPs availability; therefore the incoming SSP is translated into DUNA. ASP-a1 uses a DAUD to instruct the SGP to invoke the SS7 Sub-system Test procedure. ASP-a1 ASP-a2 SG SEP (Primary) (Backup) <--------SSP--------+ <-----------------DUNA-----------------+ +-----------------DAUD-----------------> +--------SST--------> 5.1.2.2 Successful ASP Failover scenario The following is an example of a successful failover scenario, where there is a failover from ASP-a1 to ASP-a2, i.e. Primary to Backup. During the failover, the SGP buffers any incoming data messages from the SEP, forwarding them when the Backup becomes available. Loughney (editor) [Page 77] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 ASP-a1 ASP-a2 SG SEP (Primary) (Backup) +-------------ASP Inactive-------------> <----------NTFY (ASP Inactive)---------+ <-NTFY (ASP Inact.)-+ +----ASP Active-----> <--ASP Active Ack---+ <-NTFY (ASP Active)-+ <----------NTFY (ASP Active)-----------+ 5.1.2.3 Unsuccessful ASP Failover scenario ASP-a1 ASP-a2 SG SEP (Primary) (Backup) +-------------ASP Inactive-------------> <----------NTFY (ASP Inactive)---------+ <-NTFY (ASP Inact.)-+ After some time elapses (i.e. timeout). +--------SSP--------> <--------SST--------+ 5.2 IP-IP Architecture The sequences below outline logical steps for a variety of scenarios within an IP-IP architecture. Please note that these scenarios cover a Primary/Backup configuration. Where there is a load-sharing configuration then the AS can declare availability when 1 ASP issues ASPAC but can only declare unavailability when all ASPs have issued ASPIA. 5.2.1 Establishment of SUA connectivity The following shows an example establishment of SUA connectivity. In this example, each IPSP consists of an Application Server and two ASPs. The following is established before SUA traffic can flow. A connectionless flow is shown for simplicity. Each node is configured (via MIB, for example) with the connections that need to be setup. Loughney (editor) [Page 78] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 IP SEP A IP SEP B AS A AS B ASP-a1 ASP-a2 ASP-b2 ASP-b1 (Primary) (Backup) (Backup) (Primary) [Establish SCTP Connectivity] |------------- Establish SCTP Association -------------| |------------------ Establish SCTP Association ------------------| |------- Establish SCTP Association --------| |------------ Establish SCTP Association -------------| [Establish SUA Connectivity] +----------------------ASP Up--------------------------> <--------------------ASP Up Ack------------------------+ +---------------------------ASP Up-------------------------------> <-------------------------ASP Up Ack-----------------------------+ <----------------ASP Up---------------------+ +----------------ASP Up Ack-----------------> +------------------------ASP Up-----------------------> <----------------------ASP Up Ack---------------------+ +---------------------------ACTIVE-------------------------------> <-------------------------ACTIVE Ack-----------------------------+ [Traffic can now flow directly between ASPs] +-----------------------------CLDT-------------------------------> 5.2.2 Failover scenarios The following sequences address failover of ASP 5.2.2.1 Successful ASP Failover scenario The following is an example of a successful failover scenario, where there is a failover from ASP-a1 to ASP-a2, i.e. Primary to Backup. Since data transfer passes directly between peer ASPs, ASP-b1 is notified of the failover of ASP-a1 and buffers outgoing data messages until ASP-a2 becomes available. Loughney (editor) [Page 79] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 IP SEP A IP SEP B ASP-a1 ASP-a2 ASP-b2 ASP-b1 (Primary) (Backup) (Backup) (Primary) +-----------------------------ASP Inact------------------------> <---------------------------ASP Inact Ack----------------------+ <---------------NTFY (ASP-a1 Inactive)--------------+ +---------------------ASP Act-----------------------> <-------------------ASP Act Ack---------------------+ 5.2.2.2 Unsuccessful ASP Failover scenario The sequence is the same as 4.2.2.1 except that, since the backup fails to come in then, the Notify messages declaring the availability of the backup are not sent. 6 Security 6.1 Introduction SUA is designed to carry signaling messages for telephony services. As such, SUA involves the security needs of several parties: the end users of the services; the network providers and the applications involved. Additional security requirements may come from local regulation. While having some overlapping security needs, any security solution should fulfill all of the different parties' needs. 6.2 Threats There is no quick fix, one-size-fits-all solution for security. As a transport protocol, SUA has the following security objectives: * Availability of reliable and timely user data transport. * Integrity of user data transport. * Confidentiality of user data. SUA runs on top of SCTP. SCTP provides certain transport related security features, such as: * Blind Denial of Service Attacks * Flooding * Masquerade * Improper Monopolization of Services When SUA is running in professionally managed corporate or service provider network, it is reasonable to expect that this network Loughney (editor) [Page 80] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 includes an appropriate security policy framework. The "Site Security Handbook" [2196] should be consulted for guidance. When the network in which SUA runs in involves more than one party, it may not be reasonable to expect that all parties have implemented security in a sufficient manner. End-to-end security should be the goal; therefore, it is recommended that IPSEC is used to ensure confidentiality of user payload. Consult [2409] for more information on configuring IPSEC services. 6.3 Protecting Confidentiality Particularly for mobile users, the requirement for confidentiality may include the masking of IP addresses and ports. In this case application level encryption is not sufficient; IPSEC ESP should be used instead. Regardless of which level performs the encryption, the IPSEC ISAKMP service should be used for key management. 7 IANA Considerations 7.1 SCTP Payload Protocol ID IANA has assigned a SUA value for the Payload Protocol Identifier in the SCTP DATA chunk. The following SCTP Payload Protocol Identifier is registered: SUA "4" The SCTP Payload Protocol Identifier value "4" SHOULD be included in each SCTP DATA chunk, to indicate that the SCTP is carrying the SUA protocol. The value "0" (unspecified) is also allowed but any other values MUST not be used. This Payload Protocol Identifier is not directly used by SCTP but MAY be used by certain network entities to identify the type of information being carried in a DATA chunk. The User Adaptation peer MAY use the Payload Protocol Identifier as a way of determining additional information about the data being presented to it by SCTP.A request will be made to IANA to assign CTP Payload Protocol IDs. 7.2 Port Number IANA has registered SCTP Port Number 14001 for SUA. This port number is the port that the SGPs listen to when receiving SCTP datagrams. 7.3 Protocol Extensions This protocol may also be extended through IANA in three ways: - Through definition of additional message classes. Loughney (editor) [Page 81] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 - Through definition of additional message types. - Through definition of additional message parameters. The definition and use of new message classes, types and parameters is an integral part of SIGTRAN adaptation layers. Thus, these extensions are assigned by IANA through an IETF Consensus action as defined in [RFC2434]. The proposed extension MUST in no way adversely affect the general working of the protocol. 7.3.1 IETF Defined Message Classes The documentation for a new message class MUST include the following information: (a) A long and short name for the message class; (b) A detailed description of the purpose of the message class. 7.3.2 IETF Defined Message Types Documentation of the message type MUST contain the following information: (a) A long and short name for the new message type; (b) A detailed description of the structure of the message. (c) A detailed definition and description of intended use of each field within the message. (d) A detailed procedural description of the use of the new message type within the operation of the protocol. (e) A detailed description of error conditions when receiving this message type. When an implementation receives a message type which it does not support, it MUST respond with an Error (ERR) message, with an Error Code = Unsupported Message Type. 7.3.4 IETF-defined TLV Parameter Extension Documentation of the message parameter MUST contain the following information: (a) Name of the parameter type. (b) Detailed description of the structure of the parameter field. This structure MUST conform to the general type-length-value format described earlier in the document. (c) Detailed definition of each component of the parameter value. (d) Detailed description of the intended use of this parameter type, and an indication of whether and under what circumstances multiple instances of this parameter type may be found within the same message type. Loughney (editor) [Page 82] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 8 Timer Values Ta 2 seconds Tr 2 seconds T(ack) 2 seconds T(ias) Inactivity Send timer 7 minutes T(iar) Inactivity Receive timer 15 minutes T(beat) Heartbeat Timer 30 seconds 9 Acknowledgements The authors would like to thank Brian Bidulock, Martin Booyens, Klaus Gradischnig, Miguel A. Garcia, Marja-Liisa Hamalainen, Sherry Karl, Markus Maanoja, Chirayu Patel, Michael Purcell, Michael Tuexen, Al Varney, Ben Wilson, Michael Wright and James Yu for their insightful comments and suggestions. Funding for the RFC editor function is currently provided by the Internet Society. 10 Authors' Addresses John Loughney Nokia Research Center PO Box 407 FIN-00045 Nokia Group Finland EMail: john.loughney@nokia.com Greg Sidebottom Kanata, Ontario Canada EMail: gregside@home.com Guy Mousseau Nortel Networks 3685 Richmond Rd Nepean, Ontario, Canada K2H 5B7 Stephen Lorusso Unisphere Networks 10 Technology Park Drive Westford, MA 01886 USA Phone: +1 (978) 589-0533 EMail: SLorusso@UnisphereNetworks.com Lode Coene Siemens Atea Atealaan 34 Loughney (editor) [Page 83] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 B-2200 Herentals Belgium Phone: +32-14-252081 EMail: lode.coene@siemens.atea.be Gery Verwimp Siemens Atea 34 Atealaan PO 2200 Herentals Belgium Phone: +32 14 25 3424 EMail: gery.verwimp@siemens.atea.be Joe Keller Tekelec 5200 Paramount Parkway Morrisville, NC 27560 USA EMail: joe.keller@tekelec.com Florencio Escobar Gonzalez Ericsson Spain S.A. Retama 7, 2nd floor 28045, Madrid Spain EMail: florencio.escobar@ericsson.com Steven Furniss Marconi New Century Park Coventry CV3 1HJ United Kingdom EMail: steven.furniss@marconi.com William Sully Marconi New Century Park Coventry CV3 1HJ United Kingdom EMail: william.sully@marconi.com 11 References [2196] RFC 2196, "Site Security Handbook", B. Fraser Ed., September 1997. [2396] Berners-Lee, T., Fielding, R.T. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. Loughney (editor) [Page 84] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 [2401] RFC 2401, "Security Architecture for the Internet Protocol", S. Kent, R. Atkinson, November 1998. [2434] RFC 2434 "Guidelines for Writing an IANA Considerations Section in RFCs", T. Narten, H. Alvestrand, October 1998. [2719] RFC 2719, "Framework Architecture for Signaling Transport" [ANSI-MTP] ANSI T1.111 'Signaling System Number 7 - Message Transfer Part' [ANSI SCCP] ANSI T1.112 'Signaling System Number 7 - Signaling Connection Control Part' [ANSI TCAP] ANSI T1.114 'Signaling System Number 7 - Transaction Capabilities Application Part' [ENUM] RFC 2916 "E.164 number and DNS", P. Faltstrom, September 2000. [IDNS] Blanchet, M., Hoffman, P., "Internationalized domain names using EDNS (IDNE)", , Work in progress, July 2000 [ITU-MTP] ITU-T Recommendations Q.701-Q.705, 'Signalling System No. 7 (SS7) - Message Transfer Part (MTP)' [ITU SCCP] ITU-T Recommendations Q.711-714, 'Signaling System No. 7 (SS7) - Signaling Connection Control Part (SCCP)' [ITU TCAP] ITU-T Recommendation Q.771-775 'Signaling System No. 7 SS7) - Transaction Capabilities (TCAP) [M3UA] MTP3-User Adaptation Layer , March 2001, Work in Progress. [RANAP] 3G TS 25.413 V3.5.0 (2001-03) 'Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iu Interface RANAP Signalling' [SCTP] RFC 2960 "Stream Control Transport Protocol" R. Stewart, et al, November 2000. [UTRAN IUR] 3G TS 25.422 V3.5.0 (2000-12) "Technical Specification 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Loughney (editor) [Page 85] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 UTRAN Iur Interface Signaling Transport (Release 1999)" Loughney (editor) [Page 86] Internet Draft SS7 SCCP-User Adaptation Layer July 20, 2001 Copyright Statement Copyright (C) The Internet Society (2000). All Rights Reserved. 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