Network Working Group Q. Xie INTERNET-DRAFT Motorola R. R. Stewart Cisco Systems Expires in six months Nov. 20, 2001 Endpoint Name Resolution Protocol (ENRP) 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. 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. Abstract Endpoint Name Resolution Protocol (ENRP) is designed to work in conjunction with the Aggregate Server Access Protocol (ASAP) [ASAP] to accomplish the functionality of the Reliable Server Pooling (Rserpool) requirements and architecture as defined in [RSERPOOL1] and [RSERPOOL2]. Within the operational scope of Rserpool, ENRP defines the procedures and message formats of a distributed fault-tolerant registry service for storing, bookkeeping, retrieving, and distributing pool operation and membership information. Table Of Contents 1. Introduction...............................................2 1.2 Definitions............................................2 2. Conventions................................................3 3. Message Definitions........................................4 3.1 ENRP Parameter Formats.................................4 3.1.1 IPv4 Address Parameter...........................5 3.1.2 IPv6 Address Parameter ..........................5 3.1.3 Pool Element Parameter...........................6 3.1.4 Pool Handle Parameter............................6 3.1.5 Authorization Parameter..........................7 Xie, Stewart [Page 1] Internet Draft Endpoint Name Resoluton Protocol November 2001 3.1.6 Name Server Identifier Parameter.................7 3.2 ENRP Message Formats..................................7 3.2.1 PEER_PRESENCE message...........................8 3.2.2 PEER_NAME_TABLE_REQUEST message.................9 3.2.3 PEER_NAME_TABLE_RESPONSE message................9 3.2.4 PEER_NAME_UPDATE message........................10 3.2.5 PEER_LIST_REQUEST message.......................11 3.2.6 PEER_LIST_RESPONSE message......................11 4. ENRP Operation Procedures..................................12 4.1 Basic ENRP Operations..................................12 4.1.1 PE Registration..................................12 4.1.2 PE De-registration...............................13 4.1.3 PE Re-registration...............................13 4.1.4 Name Translation.................................14 4.1.5 Server Namespace Update..........................15 4.1.5.1 Add/Update a PE..........................15 4.1.5.2 Remove a PE..............................15 4.1.6 Server Download Namespace from a Peer Server.....16 4.1.7 Server Monitor Peer Status.......................17 4.1.8 Server Download Peer List from a Peer Server.....17 4.1.9 Server Initialization............................17 4.2 Fault Management Operations............................18 4.2.1 Detect and Remove an Unreachable PE..............18 4.2.2 Server Failure Detection by Heartbeat............19 4.2.3 PE or PU Discover Home ENRP Server...............19 5. Variables and Timer Constants..............................20 5.1 Variables..............................................20 5.2 Timer Constants........................................20 6. Security COnsiderations....................................20 7. References.................................................20 8. Acknowledgements...........................................21 9. Authors' Addresses.........................................21 1. Introduction Endpoint Name Resolution Protocol (ENRP) is designed to work in conjunction with the Aggregate Server Access Protocol (ASAP) [ASAP] to accomplish the functionality of the Reliable Server Pooling (Rserpool) requirements and architecture as defined in [RSERPOOL1] and [RSERPOOL2]. Within the operation scope of Rserpool, ENRP defines the procedures and message formats of a distributed fault-tolerant registry service for storing, bookkeeping, retrieving, and distributing pool operation and membership information. Whenever appropriate, in the rest of this document we will refer to this Rserpool registry service as ENRP namespace, or simply namespace. 1.2 Definitions Xie, Stewart [Page 2] Internet Draft Endpoint Name Resoluton Protocol November 2001 This document uses the following terms: Operation scope: The part of the network visible to pool users by a specific instance of the reliable server pooling protocols. Pool (or server pool): A collection of servers providing the same application functionality. Pool handle (or pool name): A logical pointer to a pool. Each server pool will be identifiable in the operation scope of the system by a unique pool handle or "name". ENRP namespace (or namespace): A cohesive structure of pool names and relations that may be queried by an internal or external agent. Pool element (PE): A server entity that runs ASAP and has registered to a pool. Pool user (PU): A server pool user that runs ASAP. Note, a PU can also be a PE if it has registered itself to a pool. ENRP namespace server (or ENRP server): Entity which runs ENRP and is responsible for managing and maintaining the namespace within the operation scope. ENRP client channel: The communication channel through which a PE requests for ENRP namespace service. The ENRP client channel is usually defined by the transport address of the home ENRP server and a well known port number. ENRP server channel: Defined by a well known multicast IP address and a well known port number. All ENRP servers in an operation scope can send multicast messages to other servers through this channel. PEs are also allowed to multicast on this channel occasionally. Network Byte Order: Most significant byte first, a.k.a Big Endian. 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]. Xie, Stewart [Page 3] Internet Draft Endpoint Name Resoluton Protocol November 2001 3. Message Definitions All messages as well as their fields described below shall be in Network Byte Order during transmission. For fields with a length bigger than 4 octets, a number in a pair of parentheses may follow the filed name to indicate the length of the field in number of octets. 3.1 ENRP Parameter Formats ENRP parameters are defined in a Type-length-value (TLV) format as shown below. 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 Type | Parameter Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : Parameter Value : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Parameter Type: 16 bits (unsigned integer) The Type field is a 16 bit identifier of the type of parameter. It takes a value of 0 to 65534. The value of 65535 is reserved for IETF-defined extensions. Values other than those defined in specific SCTP chunk description are reserved for use by IETF. Parameter Length: 16 bits (unsigned integer) The Parameter Length field contains the size of the parameter in bytes, including the Parameter Type, Parameter Length, and Parameter Value fields. Thus, a parameter with a zero-length Parameter Value field would have a Length field of 4. The Parameter Length does not include any padding bytes. Parameter Value: variable-length. The Parameter Value field contains the actual information to be transferred in the parameter. The total length of a parameter (including Type, 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 NOT pad with more than 3 bytes. The receiver MUST ignore the padding bytes. Xie, Stewart [Page 4] Internet Draft Endpoint Name Resoluton Protocol November 2001 The Parameter Types are encoded such that the highest-order two bits specify the action that must be taken if the processing endpoint does not recognize the Parameter Type. 00 - Stop processing this ENRP message and discard it, do not process any further parameters within it. 01 - Stop processing this ENRP message and discard it, do not process any further parameters within it, and report the unrecognized parameter in an 'Unrecognized Parameter Type' error. 10 - Skip this parameter and continue processing. 11 - Skip this parameter and continue processing but report the unrecognized parameter in an 'Unrecognized Parameter Type' error. In the following sections, we define the common parameter formats used in ENRP. 3.1.1 IPv4 Address Parameter 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x1 | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IPv4 Address: 32 bits (unsigned integer) Contains an IPv4 address of the sending endpoint. It is binary encoded. 3.1.2 IPv6 Address Parameter 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x2 | Length = 20 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | IPv6 Address | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IPv6 Address: 128 bit (unsigned integer) Xie, Stewart [Page 5] Internet Draft Endpoint Name Resoluton Protocol November 2001 Contains an IPv6 address of the sending endpoint. It is binary encoded. 3.1.3 Pool Element Parameter This parameter is used in multiple ENRP message to represent an ASAP endpoint (i.e., a PE in a pool) and the associated information, such as its transport address(es), load control, and other operational status information of the PE. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x3 | Length=variable | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SCTP Port | Number of IP addrs=k | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : IP addr param #0 : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : IP addr param #1 : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : ..... : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : IP addr param #k : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Load Policy Type | Policy Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Registration Life | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Each of the IP address parameters in a PE parameter can be either an IPv4 or IPv6 address parameter. 3.1.4 Pool Handle Parameter 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x4 | Length=variable | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : Pool Handle : : : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This parameter holds a pool handle (i.e., a pool name), defined as a NULL terminated ASCII string. Xie, Stewart [Page 6] Internet Draft Endpoint Name Resoluton Protocol November 2001 3.1.5 Authorization Parameter 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x5 | Length=variable | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : Authorization Signature : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This parameter is used to hold an authorization signature. The signature is signed over the entire ASAP message and uses a preconfigured public/private key pair. The receiver of a message which includes this parameter can validate the message is from the sender by comparing the signature to one generated using the peers public key. 3.1.6 Name Server Identifier Parameter 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x7 | Length=variable | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Name Server SCTP Port | (reserved) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : IPv4 or IPv6 Addr Param : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ When a name server is multi-homed, any one of its IP addresses can be used in its Server Identifier Parameter. This is because the combination of any one of its IP addresses and its SCTP port number always uniquely identifies the server. 3.2 ENRP Message Formats The figure below illustrates the common format for all ENRP messages. Each message is formatted with a Message Type field, a message-specific Flag field, a Message Length field, and a Value field. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Type | Msg Flags | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : Message Value : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Xie, Stewart [Page 7] Internet Draft Endpoint Name Resoluton Protocol November 2001 Message Type: 8 bits (unsigned integer) This field identifies the type of information contained in the Message Value field. It takes a value from 0 to 254. The value of 255 is reserved for future use as an extension field. Message Types are encoded such that the highest-order two bits specify the action that must be taken if the message receiver does not recognize the Message Type. 00 - Stop processing this message and discard it. 01 - Stop processing this message and discard it, and report the unrecognized message in an 'Unrecognized Parameter Type' error. 10 - reserved. 11 - reserved. Message Flags: 8 bits The usage of these bits depends on the message type as given by the Message Type. Unless otherwise specified, they are set to zero on transmit and are ignored on receipt. Message Length: 16 bits (unsigned integer) This value represents the size of the message in bytes including the Message Type, Message Flags, Message Length, and Message Value fields. Therefore, if the Message Value field is zero-length, the Length field will be set to 4. The Message Length field does not count any padding. Message Value: variable length The Message Value field contains the actual information to be transferred in the message. The usage and format of this field is dependent on the Message Type. The total length of a message (including Type, Length and Value fields) MUST be a multiple of 4 bytes. If the length of the message is not a multiple of 4 bytes, the sender MUST pad the message with all zero bytes and this padding is not included in the message length field. The sender should never pad with more than 3 bytes. The receiver MUST ignore the padding bytes. 3.2.1 PEER_PRESENCE 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 Xie, Stewart [Page 8] Internet Draft Endpoint Name Resoluton Protocol November 2001 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x1 |0|0|0|0|0|0|0|R| Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Sender's Server ID param : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Receiver's Server ID param (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Authorization Parameter (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The receiving server's ID does not need to be included if the message is being multicasted. "Reply_required" (R) flag shall be set to '1' if response to this message is required, otherwise set to '0'. 3.2.2 PEER_NAME_TABLE_REQUEST 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x2 |0|0|0|0|0|0|0|0| Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Sender's Server ID param : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Receiver's Server ID param (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Authorization Parameter (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The receiving server's ID does not need to be included if the message is being multicasted. (Editor's note: we may not support multicast of this message). 3.2.3 PEER_NAME_TABLE_RESPONSE 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x3 |0|0|0|0|0|0|0|M| Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Sender's Server ID param : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Receiver's Server ID parameter : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : Pool entry #1 (see below) : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : ... : Xie, Stewart [Page 9] Internet Draft Endpoint Name Resoluton Protocol November 2001 : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : Pool entry #n (see below) : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Authorization Parameter (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ "More_to_send" (M) flag: shall be set to '1' if there are more pool entries to be sent in subsequent PEER_NAME_TABLE_RESPONSE messages. Otherwise, it shall be set to '0'. Pool entries: At least one pool entry MUST be present in the message. Each pool entry MUST start with a pool handle parameter, followed by one or more pool element (PE) parameters, i.e.: +---------------------------+ : Pool handle : +---------------------------+ : PE #1 : +---------------------------+ : PE #2 : +---------------------------+ : ... : +---------------------------+ : PE #n : +---------------------------+ 3.2.4 PEER_NAME_UPDATE 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x4 |0|0|0|0|0|0|0|0| Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Sender's Server ID param : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Receiver's Server ID param (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : Pool handle : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : Pool Element : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Update action | Xie, Stewart [Page 10] Internet Draft Endpoint Name Resoluton Protocol November 2001 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Authorization Parameter (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The receiving server's ID does not need to be included if the message is being multicasted. "Update_action" field: shall take one of the following values: 0x0 - ADD_PE: add the PE as a new member to or update the PE in the named pool in the namespace. 0x1 - DELETE_PE: delete the specified PE from the namespace. 3.2.5 PEER_LIST_REQUEST 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x5 |0|0|0|0|0|0|0|0| Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Sender's Server ID param : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Receiver's Server ID param (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Authorization Parameter (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The receiving server's ID does not need to be included if the message is being multicasted. 3.2.6 PEER_LIST_RESPONSE message This message shall contain all the peer information of the sending server. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x6 |0|0|0|0|0|0|0|R| Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Sender's Server ID param : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Receiver's Server ID parameter : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : ID of Peer Server #1 : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : ... : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : ID of Peer Server #n : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Xie, Stewart [Page 11] Internet Draft Endpoint Name Resoluton Protocol November 2001 : Authorization Parameter (optional) : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ "Reject" (R) flag: shall be set to '1' if the sender of this message is rejecting a peer list request. In such a case, this message MUST be sent with no peer server ID included. 4. ENRP Operation Procedures In this section, we discuss the procedures defined by ENRP. The procedures are divided into two groups, namely the basic ENRP operations and fault management procedures. Many of the Rserpool events call for message exchange and other activities between both a PE and an ENRP server and the ENRP server and its peers. But only the message exchange and activities between the ENRP server and its peers are considered within the ENRP protocol definition scope Procedures and message formats for communications between the PE and ENRP servers are defined in [ASAP]. However, in order to put our discussion in context, we will give brief description of the ASAP activities whenever appropreate. 4.1 Basic ENRP Operations 4.1.1 PE Registration ENRP server <-> PE: This action is part of the ASAP protocol and is defined in [ASAP]. To register itself with the name space, a PE sends a REGISTRATION message over the ENRP client channel to its home ENRP server. In the REGISTRATION message, the PE indicates the name of the pool it wishes to join in a pool handle parameter, and its port number and network access address(es) and any load control information in a PE parameter. The ENRP server handles the REGISTRATION message according to the following rules: 1) If the named pool does not exist in the namespace, the ENRP server will creates a new pool with that name in the namespace and add the PE to the pool as its first PE; 2) If the named pool already exists in the namespace, but the requesting PE is not currently a member of the pool, ENRP server will add the PE as a new member to the pool; Xie, Stewart [Page 12] Internet Draft Endpoint Name Resoluton Protocol November 2001 3) If the named pool already exists in the namespace AND the requesting PE is already a member of the pool, the ENRP server shall consider this as a re-registration case. The ENRP Server shall replace the attributes of the existing PE with the information carried in the received REGISTRATION message. 4) The ENRP server may reject the registration due to reasons such as invalid values, lack of resource, etc. In all cases, the ENRP server will reply to the requesting PE with a REGISTRATION_RESPONSE message, and will indicate in the message body whether the registration is granted or rejected. ENRP server <-> Its peers: If the registration request is granted (i.e., cases 1-3 above), the ENRP server MUST take the namespace modification action as described in section 4.1.5.1?. Otherwise, no message shall be exchanged with its peers. 4.1.2 PE De-registration ENRP server <-> PE: This action is part of the ASAP protocol and is defined in [ASAP]. To remove itself from a pool, a PE sends a DEREGISTRATION message over the ENRP client channel to its home ENRP server. In response, the home ENRP server sends a REGISTRATION_RESPONSE message to the PE and indicates in the message body whether the request is granted or rejected. If the PE is the last one of the named pool, the home ENRP server will remove the pool from the namespace as well. The ENRP server may reject the de-registration request due to reasons such as invalid parameters, etc. It should be noted that de-registration does not stop the PE from sending or receiving application messages. ENRP server <-> peers: Once the de-registration request is granted and the PE removed from its local copy of the namespace, the home ENRP server MUST take the namespace modification action described in Section 4.1.5.2. 4.1.3 PE Re-registration A PE may re-register itself to the namespace with a new set of Xie, Stewart [Page 13] Internet Draft Endpoint Name Resoluton Protocol November 2001 attributtes in order to, for example, extend its registration life, change its load policy value. However, an existing PE MUST NOT change its access address list via re-registration. Instead, to change its address list a PE shall de-register itself first and then register with the namespace as a new PE. A PE can modify its load policy value at any time via re-registration. Based on the number of PEs in the pool and the pool's load distrbution policy, this operation allows the PE to dynamically control its share of inbound messages received by the pool (also see Section 4.5.2 in [ASAP] for more on load control). ENRP server <-> PE: This action is part of the ASAP protocol and is defined in [ASAP]. To perform a re-registration, a registered PE shall simply send a new REGISTRATION message with a new set of attributes over the ENRP client channel to its home ENRP server. Upon the reception of this REGISTRATION message, the home ENRP server shall follow the same procedures described in Section 4.1.1. ENRP server <-> peers: If the REGISTRATION message is accepted, the home ENRP server shall take the action described in Section 4.1.5.1?. Otherwise, no message shall be exchanged with its peers. 4.1.4 Name Translation ENRP server <-> PE or PU: This action is part of the ASAP protocol and is defined in [ASAP]. A PE or PU can use the name translation service provided by the ENRP server to resolve a pool name to a list of accessible transport addresses of existing PEs. This requires the PE or PU to send a NAME_RESOLUTION messages to its home ENRP server and in the NAME_RESOLUTION message specify the pool name to be translated in a Pool Handle parameter. If the named pool exits in the namespace, the home ENRP server will send back a NAME_RESOLUTION_RESPONSE message that shall carry a list of PE parameters containing all information of the PEs currently registered under that pool name. This information may include the current load control policy of the pool, policy value of each PE, transport address(es) for each PE, etc. Xie, Stewart [Page 14] Internet Draft Endpoint Name Resoluton Protocol November 2001 Otherwise, the ENRP server shall respond with a NAME_UNKNOWN message. ENRP server <-> peers: None. 4.1.5 Server Namespace Update This includes a set of update operations used by an ENRP server to inform its peer(s) about the addition of a new PE, removal of an existing PE, or change of pool or PE properties. 4.1.5.1 Add/Update a PE When a new PE is granted registration to the namespace or an existing PE is granted a re-registration, the home ENRP server uses this procedure to inform all its peers. An ENRP server shall multicast over the ENRP server channel a PEER_NAME_UPDATE message with the Update_action field set to ADD_PE, indicating the addition of the new PE or the update of an existing PE to the namespace. The PE and the pool its belongs to shall be indicated in the message with a PE parameter and a Pool Handle parameter, respectively (see Section 3.2.4). Upon the reception of this PEER_NAME_UPDATE message, each of the peer ENRP servers shall take the following actions: 1) If the named pool under which the PE has been registered (or re-registered) does not exist in the peer's local copy of the namespace, the peer ENRP server shall create the named pool in its local namespace copy and add the PE to it as the first PE. It then shall copy in all other attributes of the PE carried in the message. 2) If the named pool already exists in the peer's local copy of the namespace AND the PE does not exist, the peer shall add the PE to the pool as a new PE and copy in all attributes of the PE carried in the message. 3) If the named pool exists AND the PE is already a member of the pool in its the local copy of the namespace, the peer ENRP server shall replace the attributes of the PE with the new information carried in the message. 4.1.5.2 Remove a PE This procedure is used by an ENRP server to inform its peer(s) to remove an existing PE. Xie, Stewart [Page 15] Internet Draft Endpoint Name Resoluton Protocol November 2001 An ENRP server shall multicast over the ENRP server channel a PEER_NAME_UPDATE message with the Update_action field set to DELETE_PE, indicating the removal of an existing PE from the namespace. The PE and the pool its belongs to shall be indicated in the message with a PE parameter and a Pool Handle parameter, respectively. On the reception of this PEER_NAME_UPDATE message, each peer ENRP server shall find and remove the PE from its local copy of the namespace. If the peer does not find the PE in its local copy of the namespace, it SHOULD take no action. 4.1.6 Server Download Namespace from a Peer Server This operation allows an ENRP server to request and receive a copy of the current namespace from one of its peer ENRP servers. This operation is especially useful for a newly started ENRP server to initiate its local copy of the namespace, as well as for an existing ENRP server to correct namespace inconsistency found during its operation. 1) An ENRP server shall first send a PEER_NAME_TABLE_REQUEST message directly to one of its peers. 2) Upon the reception of this message, the peer server shall initiate a download session in which the namespace shall be sent to the requesting ENRP server in one or more PEER_NAME_TABLE_RESPONSE messages. If the sending ENRP server determines that multiple PEER_NAME_TABLE_RESPONSE messages are needed for the session, it shall use the M flag in each PEER_NAME_TABLE_RESPONSE message to inform the receiving ENRP server whether or not the data in this message is the last piece of the namespace transfer. 3) During the downloading, every time the requesting ENRP server receives a PEER_NAME_TABLE_RESPONSE message, it shall transfer the data entries carried in the message into its local namespace database, and then check whether or not the data in this message is the last piece being transfered. If more data transfer is indicated, the requesting ENRP server shall send another PEER_NAME_TABLE_REQUEST message to the same peer to request for the next piece whenever it is ready. When unpacking the data entries from a PEER_NAME_TABLE_RESPONSE message into its local namespace database, the requesting ENRP server shall handle each PE by the following steps: 1) If the named pool does not exist in the local namespace, the ENRP server will creates a new pool with that name in the namespace and add the PE to the pool as the first PE; Xie, Stewart [Page 16] Internet Draft Endpoint Name Resoluton Protocol November 2001 2) If the named pool already exists in the local namespace, but the PE is not currently a member of the pool, ENRP server shall add the PE as a new member to the pool; 3) If the named pool already exists in the local namespace AND the requesting PE is already a member of the pool, the ENRP server may skip this PE. 4.1.7 Server Monitor Peer Status An ENRP server shall keep a record on the status of each of its known peers. This record is referred to as the "Peer list" of the server. An interanl variable is kept for each peer on the peer list and its value updated to the current local time each time a message of any type is received from the peer. If a message of any type is received from a peer previously unknown, the ENRP server shall create a record for the new peer and add it to the peer list. 4.1.8 Server Download Peer List from a Peer Server This operation allows an ENRP server to request from a peer server a copy of its peer list. This is useful for a new ENRP server to initiate its own peer list at startup. An ENRP server shall send a PEER_LIST_REQUEST message to a peer to request a copy of the peer list. Upon the reception of this message, the peer server shall reply with a PEER_LIST_RESPONSE message and include in the message body a list of server IDs of all known peers. If the peer itself is in the process of startup and not ready to provide a good peer list, it shall response with a PEER_LIST_RESPONSE message but set the R flag in the message to '1' to indicate that it can not grant the PEER_LIST_REQUEST. In such a case, the requesting ENRP server shall select another peer and repeat the peer list request with the new peer at a later time. 4.1.9 Server Initialization This section describes the steps a new ENRP server needs to take in order to join the other existing ENRP servers for providing the namespace service in the operation scope, or initiating the namespace service if this is the first ENRP server starting in the operation scope. Xie, Stewart [Page 17] Internet Draft Endpoint Name Resoluton Protocol November 2001 1) At startup, before getting into service, the ENRP server (initiating server) shall multicast a PEER_PRESENCE message with 'Reply_required' flag set over the ENRP server channel. This is to inform any other existing peers in the operation scope about the initiating peer's presence. 2) Upon the reception of this message, a peer shall send a PEER_PRESENCE without 'Reply_required' flag back to the initiating server, in order to help the initiating server to build a peer list. 3) If no response to its PEER_PRESENCE message are received after seconds, the initiating server shall assume that it is alone in the operation scope and shall mark the initialization process as completed. The initiation server shall skip the remaining steps and start to offer the namespace services. 4) If there are responses to its PEER_PRESENCE message, the initiating server shall then take the actions described in 4.1.8 to request a peer list from one of the peers that have responded. 5) Upon the reception of the PEER_LIST_RESPONSE message from the peer, the initiating server shall use the information carried in the message to build a complete peer list. 6) Then, the initiating server shall request to download a copy of the namespace from one of the peer, as described in 4.1.6. At this point, the initialization process is completed and the initiating server shall start to provide namespace services. 4.2 Fault Management Operations The following operations are used to detect and recover from various system faults. 4.2.1 Detect and Remove an Unreachable PE Whenever a PE finds a peer PE unreachable (e.g., via an SCTP SEND.FAILURE Notification, see section 10.2 of [RFC2960]), the former shall send an ENDPOINT_UNREACHABLE message over the ENRP client channel to its home ENRP server. The message shall contain the pool handle and one of the transport addresses of the unreachable peer PE in a PE parameter. Note: The definition and procedure of ENDPOINT_UNREACHABLE message are part of ASAP and are described in [ASAP]. Upon the reception of the ENDPOINT_UNREACHABLE message, the home ENRP server shall immediately send an ENDPOINT_KEEP_ALIVE message to the PE that is reported as unreachable. If this ENDPOINT_KEEP_ALIVE fails (i.e., it results in an SCTP Xie, Stewart [Page 18] Internet Draft Endpoint Name Resoluton Protocol November 2001 SEND.FAILURE notification), the ENRP server shall consider the PE as truly unreachable and shall remove the PE from its local copy of the namespace and take actions described in 4.1.5.2. Note: The definition and handling of the ENDPOINT_KEEP_ALIVE message by the PE are part of ASAP and are described in Sections 3.2.8? and 4.9.3? in [ASAP]. 4.2.2 Server Failure Detection by Heartbeat An ENRP server shall multicast, in every seconds, a PEER_PRESENCE message over the ENRP server channel to inform its peers that it is still operational. In the multicasted PEER_PRESENCE message, the sending ENRP server shall set the 'Replay_required' flag to '0' indicating that no response is required. An ENRP server shall keep track the time when the last message (multicast or point-to-point) was received from each known peer in the internal variable . If a peer has not been heard for more than seconds, the ENRP server shall send a point-to-point PEER_PRESENCE with 'Reply_request' flag set to '1' to that peer. If the send fails or the peer does not reply after seconds, the ENRP server shall consider the peer server dead and shall remove the peer from its peer list. When an ENRP server receives a PEER_PRESENCE message with 'Reply_request' flag set to '1', it MUST immediately respond to the sender with its own point-to-point PEER_PRESENCE message without setting the 'Replay_required' flag. 4.2.3 PE or PU Discover Home ENRP Server This action is part of ASAP protocol and is defined in [ASAP]. At its startup, or when it fails to send to (i.e., timed-out on a service request) with its current home ENRP server, a PE or PU shall initiate the following procedure to find a new home server. In the home server hunt procedure, the PE or PU shall multicast a SERVER_HUNT message over the ENRP client channel, and shall repeat sending this message every seconds until a SERVER_HUNT_RESPONSE message is received from an ENRP server. Then the PE or PU shall pick one of the ENRP servers that have responded as its new home ENRP server, and send all its subsequent the namespace service requests to this new home server. Upon the reception of the SERVER_HUNT message, an ENRP server shall Xie, Stewart [Page 19] Internet Draft Endpoint Name Resoluton Protocol November 2001 reply to the PE with a SERVER_HUNT_RESPONSE message. 5. Variables and Time Constants 5.1 Variables - the local time that a peer server was last heard (via receiving either a multicast or point-to-point message from the peer). 5.2 Timer Constants - the period for an ENRP server to send out a heartheat message to its known peers. (Default=30 secs.) - pre-set threshold for how long an ENRP server will wait before considering a silent peer server potentially dead. (Default=61 secs.) - pre-set threshold for how long a message sender will wait for a response after sending out a message. (Default=5 secs.) - pre-set threshold for how long a sender will wait before sending another SERVER_HUNT message out. (Default=5 secs.) 6. Security COnsiderations [TBD] 7. References [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [ASAP] R. R. Stewart, Q. Xie: "Aggregate Server Access Protocol (ASAP)", , work in progress. [RSERPOOL1] M. Tuexen, Q. Xie, R. R. Stewart, E. Lear, M. Shore, L. Ong, J. Loughney, M. Stillman: "Requirements for Reliable Server Pooling," , work in progress. [RSERPOOL2] M. Tuexen, Q. Xie, R. R. Stewart, E. Lear, M. Shore, L. Ong, J. Loughney, M. Stillman: "Architecture for Reliable Server Pooling," , work in progress. Xie, Stewart [Page 20] Internet Draft Endpoint Name Resoluton Protocol November 2001 [RFC2960] R. R. Stewart, Q. Xie, K. Morneault, C. Sharp, H. J. Schwarzbauer, T. Taylor, I. Rytina, M. Kalla, L. Zhang, and, V. Paxson: "Stream Control Transmission Protocol," RFC 2960, October 2000. 8. Acknowledgements The authors wish to thank John Loughney, Lyndon Ong, and Maureen Stillman and many others for their invaluable comments. 9. Authors' Addresses Randall R. Stewart 24 Burning Bush Trail. Crystal Lake, IL 60012 USA Phone: +1-815-477-2127 EMail: rrs@cisco.com Qiaobing Xie Motorola, Inc. 1501 W. Shure Drive, #2309 Arlington Heights, IL 60004 USA Phone: +1-847-632-3028 EMail: qxie1@email.mot.com Expires in six months from Nov. 2001 Xie, Stewart [Page 21] Internet Draft Endpoint Name Resoluton Protocol November 2001 Xie, Stewart [Page 22]