Internet Engineering Task Force J. Loughney Internet-Draft Nokia Expires: January 19, 2006 July 18, 2005 NSIS Extensibility Model draft-loughney-nsis-ext-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 Internet-Draft will expire on January 19, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document discusses the Next Steps in Signaling extensibility model. This model is based upon a two-layer model, where there is a transport layer and a signaling application model. This two-layer provides the ability to develope new signaling applications, while retaining the use of a common transport layer. Loughney Expires January 19, 2006 [Page 1] Internet-Draft NSIS Extensibility Model July 2005 Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. NTLP Extensibility . . . . . . . . . . . . . . . . . . . . . . 3 3.1 GIMPS Message Type . . . . . . . . . . . . . . . . . . . . 4 3.2 NSLP Identifiers . . . . . . . . . . . . . . . . . . . . . 4 3.3 Object Types . . . . . . . . . . . . . . . . . . . . . . . 4 3.4 Extensibility Flags . . . . . . . . . . . . . . . . . . . 4 3.5 Message Routing Methods . . . . . . . . . . . . . . . . . 4 3.6 Protocol Indicators . . . . . . . . . . . . . . . . . . . 5 3.7 Error Classes . . . . . . . . . . . . . . . . . . . . . . 5 3.8 Error Codes . . . . . . . . . . . . . . . . . . . . . . . 5 3.9 Router Alert Values . . . . . . . . . . . . . . . . . . . 5 4. NSLP Extensibility . . . . . . . . . . . . . . . . . . . . . . 7 4.1 Common Functionality Among Signaling Applications . . . . 7 4.1.1 Common Error Codes . . . . . . . . . . . . . . . . . . 7 4.2 NAT FW NSLP Extensibility . . . . . . . . . . . . . . . . 7 4.3 QoS NSLP Extensibility . . . . . . . . . . . . . . . . . . 7 5. QoS Model Extensibility . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 9.1 Normative References . . . . . . . . . . . . . . . . . . . 8 9.2 Informative References . . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . 9 Loughney Expires January 19, 2006 [Page 2] Internet-Draft NSIS Extensibility Model July 2005 1. Requirements notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [1]. 2. Introduction The Next Steps in Signaling Framework NSIS Framework [2] details a basic two-layer framework for signaling on the Internet. The document decomposes signaling into a two-layer model, into a generic transport layer and specific signaling layers. This model allows for an extensible model for different signaling needs on the the Internet. Currently, the NSIS working group is working on two main signaling applications - QoS signaling [3] and Nat/Firewall signaling [4]. The NSIS Transport Layer Protocol (NTLP) NTLP [5] defines a basic protocol for routing and transport of per-flow signaling along the path taken by that flow through the network; managing the underlying transport and security protocols. Above the NTLP are one or more NSIS Signaling Layer protocols, which can signal for things such as QoS, firewall control and NAT signaling QoS NSLP [3], NAT/FW NSLP [4]. These signaling applications manage their state by using the services that the NTLP provides them for signaling. This two layer approach allows for signaling applications to be developed indepently of the transport. As it is likely that the functionality entities for different signaling applications will be distinct, the 3. NTLP Extensibility The NTLP name space, identified by IANA, is divided into ranges. The extensibility rules for the ranges defined in the NTLP space are based upon the procedures by which IANA assigns values: "Standards Action" (as defined in [IANA]), "IETF Action", "Expert Review", and "Organization/Vendor Private", defined below. Extensions subject to "IETF Action" require either a Standards Track RFC, Experimental RFC or an Information RFC. Extensions subject to "Expert Review" refer to values that are to be reviewed by an Expert designated by the IESG. The code points from these ranges are typically used for experimental extensions; such Loughney Expires January 19, 2006 [Page 3] Internet-Draft NSIS Extensibility Model July 2005 assignments MUST be requested by either Experimental or Information RFCs that document their use and processing, and the actual assignments made during the IANA actions for the document. Values from "Expert Review" ranges MUST be registered with IANA. "Organization/Vendor Private" ranges refer to values that are enterprise-specific. In this way, different enterprises, vendors, or Standards Development Organizations (SDOs) can use the same code point without fear of collision. NTLP specifies the following registries listed below. 3.1 GIMPS Message Type The NTLP common header contains a one-byte message type field (initially distinguishing Query, Response, Confirm and Data messages). New message types require Standards Action. 3.2 NSLP Identifiers Each signaling application requires one of more NSLPIDs (different NSLPIDs may be used to distinguish different classes of signaling node, for example to handle different aggregation levels or different processing subsets). An NSLPID must be associated with a unique RAO value. IETF Action is required to allocate a new NSLP Identifier. 3.3 Object Types The generic object header as a field which distinguish differentes ranges for different allocation styles (standards action, expert review etc.) and different applicability scopes (experimental/ private, NSLP-specific); by default, object types are public and shared between all NSLPs. When a new object type is defined, the extensibility bits must also be defined. 3.4 Extensibility Flags The generic object header defined in NTLP contains reserved flag bits. These are reserved for the definition of more complex extensibility encoding schemes. Standards Action is required to define new Extensibility Flags. 3.5 Message Routing Methods NTLP allows the idea of multiple message routing methods. The message routing method is indicated in the leading 2 bytes of the MRI object. NTLP allocates 2 bits for experimental Routing Methods, for use in closed networks for experimentation purposes. Standards Loughney Expires January 19, 2006 [Page 4] Internet-Draft NSIS Extensibility Model July 2005 Action is required to allocate new Routing Methods. 3.6 Protocol Indicators The GIMPS design allows the set of possible protocols to be used in a messaging association to be extended. Every new mode of using a protocol is given by a Protocol Indicator, which is used as a tag in the Node Addressing and Stack Proposal objects. New protocol indicators require IETF Action. Allocating a new protocol indicator requires defining the higher layer addressing information in the Node Addressing Object that is needed to define its configuration. 3.7 Error Classes The Error Classes are primarily to aid human or management interpretation of otherwise unknown error codes. These are allocated on an Expert Review basis. 3.8 Error Codes Error codes are shared across all NSLPs. When a new error code is allocated, the Error Class and the format of any associated error- specific information must also be defined. These are allocated on an Expert Review basis. 3.9 Router Alert Values Router Alert Option (RAO) values are allocated on the basis of IETF consensis. However, new RAO values SHOULD NOT be allocated for each new NSLP. Careful consideration needs to be exercised when choosing to allocate a new RAO value. This section discusses some considerations on how to choose if an existing RAO option should be chosen or a new RAO should be allocated for an NSLP The RAO contains a 16 bit value field, 35 values which have currently been assigned by IANA. The use of the RAO is the primary mechanism to indicate that an NTLP message should be intercepted by a particular node. There are two basic reasons why a NTLP node might wish not to intercept a particular message. The first reason would be because the message is for a signaling application that the node does not process. The second reason would be because the node is processes signaling messages at the aggregate level, not for individual flow, even though the signaling application is present on the node. However, these reasons do not preclude a node processing several RAO values, implying it supports several different signaling applications. Some of this information can be encoded in the RAO value field, which Loughney Expires January 19, 2006 [Page 5] Internet-Draft NSIS Extensibility Model July 2005 then allows messages to be filtered on the fast path. There is a tradeoff between two approaches here, whose evaluation depends on whether the processing node is specialised or general purpose: Fine-Grained: The signaling application (including specific version) and aggregation level are directly identified in the RAO value. A specialised node which handles only a single NSLP can efficiently ignore all other messages; a general purpose node may have to match the RAO value in a message against a long list of possible values. Coarse-Grained> RAO values are allocated are ased on common applications or sets of applications (such as 'All QoS Signaling Applications'). This speeds up the processing in a general purpose node, but a specialised node may have to carry out further processing on the NTLP common header to identify the precise messages it needs to consider. These considerations imply that the RAO value should not be tied directly to the NSLPID, but should be selected for the application on broader considerations of likely deployment scenarios. Note that the exact NSLP is given in the GIMPS common header, and some implementations may still be able to process it on the fast path. The semantics of the node dropping out of the signaling path are the same however the filtering is done. There is a special consideration in the case of the aggregation level. In this case, whether a message should be processed depends on the network region it is in (specifically, the link it is on). There are then two basic possibilities: All routers have essentially the same algorithm for which messages they process, i.e. all messages at aggregation level 0. However, messages have their aggregation level incremented on entry to an aggregation region and decremented on exit. Router interfaces are configured to process messages only above a certain aggregation level and ignore all others. The aggregation level of a message is never changed; signaling messages for end to end flows have level 0, but signaling messages for aggregates are generated with a higher level. The first technique requires aggregating/deaggregating routers to be configured with which of their interfaces lie at which aggregation level, and also requires consistent message rewriting at these boundaries. The second technique eliminates the rewriting, but requires interior routers to be configured also. It is not clear what the right trade-off between these options is. Loughney Expires January 19, 2006 [Page 6] Internet-Draft NSIS Extensibility Model July 2005 4. NSLP Extensibility 4.1 Common Functionality Among Signaling Applications While NSIS has adopted a two-layer signaling approach, in practice, there is much in common between different NSLPs. This section covers the common values as well as specific NSLP registries. 4.1.1 Common Error Codes There is a common Error Code format across all NSLPs. The Error Code contains an Error Type, Error Code, NSLPID and an optional additional error field. This document will list the main Error Types and Error Codes. Allocation of new Error Types require IETF Action; allocation of new Error Codes is 'first come, first serve.' 4.2 NAT FW NSLP Extensibility TBA 4.3 QoS NSLP Extensibility TBA 5. QoS Model Extensibility The QoS NSLP provides signaling for QoS reservations on the Internet. The QoS NSLP decouples the resource reservation model or architecture from the signaling. The QoS specification is defined in QSpec [6]. New QSpecs require IETF action, which defines the elements within the QSpec. 6. IANA Considerations This document outlines the basic rules for extending NSIS protocols. This instructions IANA on allocation policies for NSIS protocols. 7. Security Considerations This document is an informational document, outlining the extensibility model of the NSIS protocol suite. As such, this document does not impact the security of the Internet directly. 8. Acknowledgements This document borrows some ideas and some text from RFC3936 [7], Loughney Expires January 19, 2006 [Page 7] Internet-Draft NSIS Extensibility Model July 2005 Procedures for Modifying the Resource reSerVation Protocol (RSVP). 9. References 9.1 Normative References [2] Hancock, R., "Next Steps in Signaling: Framework", draft-ietf-nsis-fw-07 (work in progress), December 2004. [4] Stiemerling, M., "NAT/Firewall NSIS Signaling Layer Protocol (NSLP)", draft-ietf-nsis-nslp-natfw-06 (work in progress), May 2005. [5] Schulzrinne, H. and R. Hancock, "GIMPS: General Internet Messaging Protocol for Signaling", draft-ietf-nsis-ntlp-06 (work in progress), May 2005. [3] Bosch, S., Karagiannis, G., and A. McDonald, "NSLP for Quality- of-Service signaling", draft-ietf-nsis-qos-nslp-06 (work in progress), February 2005. [6] Ash, J., "QoS-NSLP QSPEC Template", draft-ietf-nsis-qspec-05 (work in progress), July 2005. [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 9.2 Informative References [7] Kompella, K. and J. Lang, "Procedures for Modifying the Resource reSerVation Protocol (RSVP)", BCP 96, RFC 3936, October 2004. Author's Address John Loughney Nokia Itamerenkatu 11-13 Helsinki 00180 Finland Phone: +358504836242 Email: john.loughney@nokia.com Loughney Expires January 19, 2006 [Page 8] Internet-Draft NSIS Extensibility Model July 2005 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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