INTERNET-DRAFT D. Meyer (Editor) Category Informational Expires: April 2004 October 2003 Routing Protocol Overloading -- Issues, Concerns, and Considerations Status of this Document This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. 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 RFC 2119 [RFC 2119]. This document is a product of the RPO Design Team. Comments should be addressed to the authors, or the mailing list at rpo@lists.uoregon.edu. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Meyer, et. al. [Page 1] INTERNET-DRAFT Expires: April 2004 October 2003 Abstract The Routing Protocol Overloading (RPO) design team was formed to document the concerns and considerations surrounding the use of Internet routing protocols for functions not directly related to routing of IP packets within the Internet and IP networks. This document is the output of that activity. Meyer, et. al. [Page 2] INTERNET-DRAFT Expires: April 2004 October 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Scope of this Work . . . . . . . . . . . . . . . . . . . . . . 5 3. Problem Statement. . . . . . . . . . . . . . . . . . . . . . . 6 3.1. Risk, Interference, and Application Fit . . . . . . . . . . 6 3.1.1. Risk: Software Engineering . . . . . . . . . . . . . . . 7 3.1.2. Interference: Protocol Specification/Dynamic Behavior . 7 3.1.3. Application Fit. . . . . . . . . . . . . . . . . . . . . 7 4. Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.1. Layer 3 Routing Information . . . . . . . . . . . . . . . . 8 4.2. Reachability Information. . . . . . . . . . . . . . . . . . 8 4.3. Auxiliary (non-routing) Information . . . . . . . . . . . . 8 4.4. Address Family Identifier (AFI) . . . . . . . . . . . . . . 9 4.5. Subsequent Address Family Identifier (SAFI) . . . . . . . . 9 4.6. Network Layer Reachability. . . . . . . . . . . . . . . . . 9 4.7. Application . . . . . . . . . . . . . . . . . . . . . . . . 10 4.8. Routing Protocol. . . . . . . . . . . . . . . . . . . . . . 10 4.9. Fate Sharing. . . . . . . . . . . . . . . . . . . . . . . . 10 5. Architectural Models . . . . . . . . . . . . . . . . . . . . . 10 5.1. General Purpose Transport Infrastructure (GPT) Model. . . . 11 5.2. Special Purpose Transport Infrastructure (SPT) Model. . . . 11 6. Analyzing Risk and Interference. . . . . . . . . . . . . . . . 12 6.1. Risk: Code Impact, and Resource Sharing . . . . . . . . . . 12 6.1.1. Code Impact. . . . . . . . . . . . . . . . . . . . . . . 13 6.1.2. Resource Sharing . . . . . . . . . . . . . . . . . . . . 13 6.1.2.1. Resource Sharing and Operating System Level Issues . 14 6.2. Interference. . . . . . . . . . . . . . . . . . . . . . . . 14 7. BGP and TCP Models: Risk and Interference. . . . . . . . . . . 15 7.1. Risk. . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7.1.1. Code Impact. . . . . . . . . . . . . . . . . . . . . . . 15 7.1.2. Resource Sharing . . . . . . . . . . . . . . . . . . . . 16 7.2. Interference. . . . . . . . . . . . . . . . . . . . . . . . 17 7.3. The TCP Model and Interference. . . . . . . . . . . . . . . 17 7.4. The BGP Model and Interference. . . . . . . . . . . . . . . 18 8. Operational Implications . . . . . . . . . . . . . . . . . . . 18 9. Conclusions and Recommendations. . . . . . . . . . . . . . . . 18 10. Intellectual Property . . . . . . . . . . . . . . . . . . . . 18 11. Design Team . . . . . . . . . . . . . . . . . . . . . . . . . 18 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19 13. Security Considerations . . . . . . . . . . . . . . . . . . . 20 14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 15. References. . . . . . . . . . . . . . . . . . . . . . . . . . 21 Meyer, et. al. [Page 3] INTERNET-DRAFT Expires: April 2004 October 2003 15.1. Normative References . . . . . . . . . . . . . . . . . . . 21 15.2. Informative References . . . . . . . . . . . . . . . . . . 23 16. Editor's Address. . . . . . . . . . . . . . . . . . . . . . . 24 17. Full Copyright Statement. . . . . . . . . . . . . . . . . . . 24 Meyer, et. al. [Page 4] INTERNET-DRAFT Expires: April 2004 October 2003 1. Introduction The stability of the global Internet routing system has been the subject of much research (see e.g., [RVBIB]) and discussion on various IETF mailing lists [IETFOL]. Much of the research into the routing system has centered around the analysis of the dynamics and stability of the Border Gateway Protocol Version 4 [BGP] (hereafter referred to as BGP). However, while the theoretical properties of BGP remains a topic of great interest, a more recent discussion has focused on effects of the addition of new types of Network Layer Reachability Information, or NLRI to BGP. In particular, the advent of two BGP attributes, Multiprotocol Reachable NLRI (MP_REACH_NLRI), and Multiprotocol Unreachable NLRI (MP_UNREACH_NLRI) [RFC2858], have made it possible to encode and transport a wide variety of features and their associated signaling using the BGP transport infrastructure. Examples include IPv6 [RFC2460], flow specification rules [FLOW], virtual private LAN services [VPLS], and virtual private Wire Service [VPWS]. Finally, while this document outlines the concerns and issues surrounding using the BGP infrastructure as a generic feature and signaling transport, note that the similar concerns apply to the Interior Gateway Protocols (IGPs) in common use (e.g., ISIS [RFC1142] or OSPF [RFC2328]), although at this time there is no specific material on IGPs. The rest of this document is organized as follows: Section 2 outlines the scope of this work. Section 3 introduces the problem statement which is the focus of this document, section 4 provides definitions, and section 5 outlines the main architectural models that are discussed. The remaining sections discuss the the implications of those models. 2. Scope of this Work It is the intention of the RPO design team that this document serve as a guide for both protocol designers and network operators, and that an attempt is being made to shine a neutral light on the implications (in the form of both benefits and offshoots) associated with proceeding to employ routing protocols to enable additional feature sets and functionality, or to design new mechanisms for carriage of that information. Meyer, et. al. Section 2. [Page 5] INTERNET-DRAFT Expires: April 2004 October 2003 The issues, concerns and considerations discussed in this document focus on the implications for BGP [BGP,RFC1771]. It is important to note that similar issues will arise when considering generalizations to the information that the IGPs carry. 3. Problem Statement The advent of the MP_REACH_NLRI and MP_UNREACH_NLRI attributes, combined with the resulting generalization to the BGP infrastructure, have created the opportunity to use BGP to transport a wide variety of data types and their associated signaling. The combination of a BGP data type and its associated signaling is frequently called an "application"; example applications include the IPv4 routing system, flow specification rules [FLOW], auto-discovery mechanisms for Layer 3 VPNs [BGPVPN], and virtual private LAN services [VPLS]. More recently, the discussion in the IETF community has focused on the use of the BGP as a generalized feature transport infrastructure [IETFOL]. The debate has recently intensified due to the emergence of a new class of application that use the BGP infrastructure to distribute information that is not directly related to inter-domain routing. Examples of such applications include the use of the BGP transport infrastructure to provide auto-discovery for Layer 3 VPNs [BGPVPN] and the virtual private LAN services mentioned above. 3.1. Risk, Interference, and Application Fit As mentioned above, much of the debate surrounding these new uses of BGP transport infrastructure has focused on the potential tradeoffs between the stability of the Internet routing system as effected by the deployment of new applications, and the desire on the part of service providers to rapidly deploy these new applications. These tradeoffs have at times been described in terms of risk, interference, and application fit. Risk models the software engineering impact of new applications on a generic implementation, while interference models the impact of new applications on protocol definition and behavior. Finally, application fit models the similarity between application's data and signaling requirements and a specific distribution algorithm. Each is described below. Meyer, et. al. Section 3.1. [Page 6] INTERNET-DRAFT Expires: April 2004 October 2003 3.1.1. Risk: Software Engineering Risk attempts to assess the robustness tradeoffs inherent in the addition of new applications to a given implementation. In this case, risk models the impact of generic software engineering issues on a given implementation. These issues including the impact of new applications on existing implementations and on the fate sharing properties of those implementations. A second aspect of risk lies in the trade-off of extending an existing protocol (with the risks in 3.1.1), versus designing, implementing, and deploying a new protocol. (more from Kireeti here). 3.1.2. Interference: Protocol Specification/Dynamic Behavior Interference, on the other hand, models the potential for a new application to adversely effect the operation of an existing implementation, at the protocol level, by inadvertently introducing a detrimental dependency of some kind. That is, is it possible that we might, by some extension, break something fundamental to a protocol's specification? For example, could we create a new state which introduces an unanticipated deadlock situation to occur? Or could we destabilize the distributed behavior of the protocol? Or might we simply run out of the attributes or bits available (as happened, for example, with RADIUS [RFC2138])? 3.1.3. Application Fit Application fit refers to the matching of the requirements of the data to be distributed with the underlying capabilities of a distribution mechanism. Broadcast, multicast and unicast distribution mechanisms in use today. When considering a distribution mechanism (such as BGP), an important issue to address is whether the behavior of the distribution mechanism matches the distribution needs. For example, it is clearly inefficient to broadcast data to all peers that is only required between two peers, just as it is inefficient to create many unicasts of data that is required by all peers when a single broadcast would do. Meyer, et. al. Section 3.1.3. [Page 7] INTERNET-DRAFT Expires: April 2004 October 2003 4. Definitions 4.1. Layer 3 Routing Information Layer 3 routing information represents either link state information or network reachability information. Link state information represents Layer 3 adjacencies and topology. Link state routing protocols, such as OSPF [RFC2328] and ISIS [RFC1142], flood link state information throughout an IGP domain, so that each participating router maintains an identical copy of a database that is computed to reflect the complete Layer 3 topology. Layer 3 reachability information represents Layer 3 networks that are reachable through gateway routers. Distance/path vector routing protocols, such as BGP, distribute Layer 3 reachability information among routing domains. Routers use both types of Layer 3 routing information (link state and reachability) to produce IP forwarding tables. For purposes of this discussion, "routing information" relates to the Layer 3 inter-domain routing data traditionally carried by BGP. 4.2. Reachability Information Reachability information refers to information describing some locale of a network, along with how one can reach it, and perhaps also containing attributes that indicate the suitability of the implied | path to the network locale. An example is VPLS information [VPLS]. 4.3. Auxiliary (non-routing) Information Auxiliary Information is any information that is exchanged by routers which is neither Layer 3 routing information, nor reachability information. For example, flow specification [FLOW] is auxiliary information. Meyer, et. al. Section 4.3. [Page 8] INTERNET-DRAFT Expires: April 2004 October 2003 4.4. Address Family Identifier (AFI) An Address Family contains addresses that share common structure and semantics. An Address Family Identifier (AFI) uniquely identifies each address family. Several routing protocol messages contain a field that represents the AFI. The AFI identifies the address type used by another data item contained in that message. The Routing Information Protocol (RIP) [RFC2453], Distance Vector Multicast Routing Protocol (DVMRP) [RFC1075], and BGP all employ the AFI field. For example, the BGP MP_REACH_NLRI and MP_UNREACH_NLRI attributes contain an AFI field. These BGP attributes also contain a NLRI field that enumerates reachable or unreachable subnetworks corresponding to the associated address family. The AFI field indicates the address type by which reachable subnetworks are identified. When BGP is used to distribute Layer 3 routing information, AFIs can indicate the following address types: IPv4, IPv6, VPNv4 [RFC2547BIS]. When BGP is used to distribute auxiliary information, AFIs can indicate other address families. 4.5. Subsequent Address Family Identifier (SAFI) A Subsequent Address Family Identifier (SAFI) is part of the BGP MP_REACH_NLRI and MP_UNREACH_NLRI attributes. These BGP attributes also contain a NLRI field that enumerates reachable or unreachable subnetworks. The SAFI augments the AFI, carrying additional information regarding networks enumerated in the NLRI field. 4.6. Network Layer Reachability Network Layer Reachability Information, or NLRI is the data described by the AFI/SAFI fields [AFI,SAFI]. While these concepts were originally described for protocols such as DVMRP [RFC1075], the bulk of the generalization of the NLRI described in this document derive from the introduction to BGP of the MP_REACH_NLRI and MP_UNREACH_NLRI attributes [RFC2858]. Meyer, et. al. Section 4.6. [Page 9] INTERNET-DRAFT Expires: April 2004 October 2003 4.7. Application The term application is used in this document to refer to the combination of a BGP data type and any signaling data that is carried by BGP in support of the service the data type carries. The data type is typically described an AFI/SAFI, while the actual data is frequently contained in both NLRI and BGP community attributes [RFC1997]. 4.8. Routing Protocol A routing protocol is composed of two basic components: a data distribution algorithm and a decision algorithm. A router typically obtains Layer 3 routing information via its data distribution algorithm, and it uses this information to produce an IP forwarding table (by applying the protocol's decision algorithm to the received routing data). Note that it is the use of BGP's data distribution algorithm that is the focus of this document. However, when judging application fit, one may also consider whether the decision algorithms suit the application. 4.9. Fate Sharing The fate sharing principle for end to end network protocols was first enunciated by Dave Clark [CLARK]. As applied to software systems, fate sharing refers to the sharing of common resources among a group of applications. In our case, the particular "fate" of most interest is the ability of one application, call it application A, to cause an application with which it is fate sharing, call it application B, to experience one or more faults due to faults in application A. In the case of BGP, one way to reduce fate sharing is to run applications A and B in seprate BGP sessions. 5. Architectural Models In this section, we consider the two architectural models which are motivated by salient questions considered in this document, namely: Does the BGP distribution protocol suit a particular Meyer, et. al. Section 5. [Page 10] INTERNET-DRAFT Expires: April 2004 October 2003 application, and if it does, what are the effects on the global routing system (if any) of carrying that application using the BGP distribution protocol? That is: (i). Does the BGP distribution protocol suit a particular application? (ii). What are the effects on the global routing system (if any) of carrying that application using the BGP distribution protocol? These questions must be analyzed in terms of the the cost of protocol and code development, as well as operational expense that may be incurred by utilizing (or not utilizing) the mechanisms already present in BGP. Two models, describing alternate viewpoints, are examined in the following sections. 5.1. General Purpose Transport Infrastructure (GPT) Model The GPT model models BGP data distribution infrastructure as a generic application transport mechanism. As such, it focuses on "application fit", and assumes that the tradeoffs, both in terms of risk and interference can be managed in an efficient manner. As a result, the GTP models these issues not in terms of whether the application and signaling data that need to be distributed are part of some particular class (routing, in this case), but rather whether the requirements for the distribution these attributes are similar enough to the distribution mechanisms of BGP. In those cases when they are sufficiently similar, BGP becomes a logical candidate for such a transport infrastructure. Note that this is not because of the nature of information distributed, but rather due to the similarity in the transport requirements. There are other operational considerations that make BGP a logical candidate, including its close to ubiquitous deployment in the Internet (as well as in intra-nets), its policy capabilities, and operator comfort levels with the technology. 5.2. Special Purpose Transport Infrastructure (SPT) Model The SPT model, on the other hand, models the BGP infrastructure as a Meyer, et. al. Section 5.2. [Page 11] INTERNET-DRAFT Expires: April 2004 October 2003 special purpose transport designed specifically to transport inter- domain routing information. As such, it is more sensitive to risk and interference than to application fit. There are two basic arguments supporting the SPT model: The first is based on the perceived risk profile of the fate sharing involved in adding new applications to the BGP transport infrastructure. The concern here is that the new applications being added to BGP will cause software quality degrade, and hence destabilize the global routing system. This position is based upon well understood software engineering principles, and is strengthened long-standing experience that there is a direct correlation between software features and bugs [MULLER1999]. This concern is augmented by the fact that in many cases, the existence of the code for these features, even if unused, can also cause destabilization in the routing system, since in many cases software faults cannot be isolated. A second concern is based on interference arguments, notably that the increase in complexity of BGP due to the number of data types that it carries can also potentially destabilize the global routing system. This concern is based on a wide range of concerns, including that the interaction of BGP dynamics and current deployment practices are poorly understood, and that the addition of non-routing data types may adversely effect convergence and other scaling properties of the global routing system. 6. Analyzing Risk and Interference One way to frame the tradeoffs involved in analyzing risk is in terms of the software engineering issues surrounding where an implementation might demultiplex among applications. An implementation's application demultiplexing point directly effects a given implementation's risk profile due to its effects on existing code, and on the system resources it requires to be shared among those applications. 6.1. Risk: Code Impact, and Resource Sharing For purposes of this discussion, we consider two models of application demultiplexing: The first model, which we will call the "BGP model", based on the current BGP model, provides a single point for demultiplexing all applications (i.e., the AFI/SAFI). The BGP Meyer, et. al. Section 6.1. [Page 12] INTERNET-DRAFT Expires: April 2004 October 2003 model is and instantiation of the GPT model. The second model, which we will call the "TCP model", provides an application demultiplexing point above BGP (typically at the TCP port level). In particular, in the BGP model, applications currently share a common transport session, while the TCP model envisions one or more applications per transport session. The TCP model an instantiation of the SPT model. Finally, note that these models can have very risk profiles with respect to code impact and resource sharing. Some of the questions relating to risk assessment are considered below. 6.1.1. Code Impact In this section, we outline the high-level questions one might ask in assessing the difference in risk between TCP model and the BGP model based on their effect on an existing code base. o Does the code below the demultiplexing point need to be changed when a new application is added? o Does the code in existing applications have to be changed when a new application is added (that is, to what extent are the applications decoupled)? o Can the code in separate applications be developed, tested, released, debugged and packaged independently from other applications? o Is there significant code below the demultiplexing point that can be shared among all applications? 6.1.2. Resource Sharing In this section, we outline the high-level questions one might ask in assessing the difference in risk between TCP model and the BGP model with respect to the requirements and properties of the system resource sharing it they require. Meyer, et. al. Section 6.1.2. [Page 13] INTERNET-DRAFT Expires: April 2004 October 2003 o Do applications have to compete for socket buffers, and hence have to potential to block or starve each other (at the TCP port level)? o Do applications have to compete for possible protocol-level transport-related buffers and queues, and hence have the potential to starve or block each other at the protocol send/receive level? o Do applications have to compete for a possible per-connection processing time budget, hence have the potential to starve each other at the intra-process scheduling level? o Do applications have to compete for resources within the network (e.g., bandwidth), when the protocol session spans multiple hops ? 6.1.2.1. Resource Sharing and Operating System Level Issues In this section, we outline the high-level questions one might ask in assessing the difference in risk between TCP model and the BGP model based on the effect on resource sharing at the operating system level. o Do applications share a common scheduling context? That is, do applications have to compete for per-process scheduling budgets? o What is the degree of fate sharing between applications? 6.2. Interference Interference models the potential for a new application to effect the behavior of an existing application or applications. For example, in the case of the Internet routing system, one might ask if a certain application "interferes" with IPv4 Unicast routing by effecting some aspect of its protocol operation (e.g., convergence time). Interference in the Internet routing system has it is roots in the observation that the routing system itself can be described as highly Meyer, et. al. Section 6.2. [Page 14] INTERNET-DRAFT Expires: April 2004 October 2003 self-dissimilar, with extremely different scales and levels of abstraction. Complex systems with this property are susceptible "coupling", which RFC 3439 [RFC3439] defines as follows: The Coupling Principle states that as things get larger, they often exhibit increased interdependence between components. COROLLARY: The more events that simultaneously occur, the larger the likelihood that two or more will interact. This phenomenon has also been termed "unforeseen feature interaction" [WILLINGER2002]. That is, interference, if and where it occurs, has its roots protocol complexity and is frequently the result of application coupling. 7. BGP and TCP Models: Risk and Interference In this section, we analyze the BGP and TCP models risk and interference. 7.1. Risk As mentioned above, risk models the robustness tradeoffs around generic software architecture and engineering associated with protocol implementations, including the impact on impact on existing protocol implementations, and on the fate sharing properties of those implementations. In the following sections we consider these components of risk for both the TCP and BGP models. 7.1.1. Code Impact In this section, we outline the answers to the questions posed above. o Does the code below the demultiplexing point need to be changed when a new application is added? Such code changes are unlikely to be required in the TCP model, as the TCP model envisions that a new application will have a new demultiplexing point (port). Meyer, et. al. Section 7.1.1. [Page 15] INTERNET-DRAFT Expires: April 2004 October 2003 In theory, the BGP model does not require new code below the demultiplexing point either. Specifically, it is possible to isolate code below the demultiplexing point with suitable abstraction and constructs such as AFI/SAFI API registries. o Does the code in existing applications have to be changed when a new application is added (that is, to what extent are the applications decoupled)? The TCP model envisions application independence with respect to demultiplexing point. As such, it is unlikely to require such changes. However, it is important to note that good software engineering practices encourage code reuse and construction of general purpose libraries. As a result, if applications share libraries and/or other code, the practical independence decreases, and consequently risk increases. The same analysis can be made for the BGP model, since in this case we are already demultiplexing on the AFI/SAFI fields. o Can the code in separate applications be developed, tested, released, debugged and packaged independently from other applications? While this is theoretically possible in the TCP model (and possibly harder in the BGP model) practice and experience has shown that achieving this type of independence is difficult in either model. 7.1.2. Resource Sharing In this section, we address the questions raised above to assess the difference in risk between TCP model and the BGP model based on the effect on resource sharing considerations. o Do applications have to compete for socket buffers, and hence have to potential to block or starve each other (at the TCP level)? The TCP model does not require applications to compete for socket level resources. It should also be possible to achieve this type of application independence in the BGP model with multi-session extensions to BGP (i.e., grouping of one or more AFI/SAFI per TCP session). Meyer, et. al. Section 7.1.2. [Page 16] INTERNET-DRAFT Expires: April 2004 October 2003 o Do applications have to compete for possible protocol-level transport-related buffers and queues, and hence have the potential to starve or block each other at the protocol send/receive level? Again, while the TCP model does not require competition for transport-level resources, it should be possible to achieve similar behavior with the BGP model and multi-session extensions. o Do applications have to compete for a possible per-connection processing time budget, hence have the potential to starve each other at the intra-process scheduling level? Applications written to the the TCP model should require this type of resource competition. Note, however, that it should be possible in the BGP model with multi-session extensions to BGP. o Do applications have to compete for resources within the network (e.g., bandwidth), when the protocol session spans multiple hops ? Neither the TCP model nor the BGP model (again, with multi-session extensions) should be require competition for network resources in this case. 7.2. Interference Interference concerns stem from the possibility that application coupling can lead to the destabilization of the Internet routing system in unanticipated and unexpected ways. In this section we consider interference properties of the TCP and BGP models. 7.3. The TCP Model and Interference Meyer, et. al. Section 7.3. [Page 17] INTERNET-DRAFT Expires: April 2004 October 2003 7.4. The BGP Model and Interference 8. Operational Implications 9. Conclusions and Recommendations 10. Intellectual Property The IETF takes no position regarding the validity or scope of any intellectual property 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; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11 [RFC2028]. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. 11. Design Team The design team that produced this document consisted of Daniel Awduche (awduche@awduche.com), Ron Bonica (Ronald.P.Bonica@mci.com), Hank Kilmer (hank@rem.com), Kireeti Kompella (kireeti@juniper.net), Chris Lewis (chrlewis@cisco.com), Danny McPherson (danny@tcb.net), David Meyer (dmm@1-4-5.net) and Pete Whiting (pete@sprint.net). Meyer, et. al. Section 11. [Page 18] INTERNET-DRAFT Expires: April 2004 October 2003 12. Acknowledgments David Ball, Eric Rosen, and Mark Townsley made many insightful comments on earlier versions of this draft. Meyer, et. al. Section 12. [Page 19] INTERNET-DRAFT Expires: April 2004 October 2003 13. Security Considerations This document specifies neither a protocol nor an operational practice, and as such, it creates no new security considerations. 14. IANA Considerations This document creates a no new requirements on IANA namespaces [RFC2434]. Meyer, et. al. Section 14. [Page 20] INTERNET-DRAFT Expires: April 2004 October 2003 15. References 15.1. Normative References [AFI] http://www.iana.org/assignments/address-family- numbers [BGP] Rekhter, Y, T.Li, and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", draft-ietf-idr-bgp4-20.txt, Work in Progress. [BGPVPN] Ould-Brahim, H., E. Rosen, and Y. Rekhter, "Using BGP as an Auto-Discovery Mechanism for Provider-provisioned VPNs", draft-ietf-l3vpn-bgpvpn-auto-00.txt, July, 2003. Work in Progress. [CLARK] Clark, D., "Design Philosophy of the DARPA Internet Protocols", Computer Communication Review, volume 25, number 1, January 1995. ISSN # 0146-4833. [EXTCOMM] Sangali, S., D. Tappan, and Y. Rekhter, "BGP Extended Communities Attribute", draft-ietf-idr-bgp-ext-communities-06.txt. Work in Progress. [FLOW] Marques, P, et. al., "Dissemination of flow specification rules", draft-marques-idr-flow-spec-00.txt, June, 2003. Work in Progress. [MULLER1999] Muller, R. et. al., "Control System Reliability Requires Careful Software Installation Procedures", International Conference on Accelerator and Largeand Large Experimental Physics Systems, 1999, Trieste, Italy. [RFC1075] Waitzman, D., C. Partridge, and S. Deering, "Distance Vector Multicast Routing Protocol", RFC 1075, November, 1988. [RFC1142] Oran, D. Editor, "OSI IS-IS Intra-domain Routing Protocol", RFC 1142, February, 1990. [RFC1771] Rekhter, Y., and T. Li, "A Border Gateway Protocol 4 (BGP-4)", RFC 1771, March 1995. Meyer, et. al. Section 15.1. [Page 21] INTERNET-DRAFT Expires: April 2004 October 2003 [RFC1958] Carpenter, B., "Architectural principles of the Internet", Editor. RFC 1958, June 1996. [RFC1997] Chandra, R., P. Traina, and T. Li, "BGP Communities Attribute", RFC 1997, August, 1996. [RFC2138] Rigney, C., et. al., "Remote Authentication Dial In User Service (RADIUS)", RFC 2138, April, 1997. [RFC2328] Moy, J., "OSPF Version 2", RFC 2328, April, 1998. [RFC2453] Malkin, G., "RIP Version 2", RFC 2453, November, 1998. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December, 1998. [RFC2547BIS] Rosen, E., et. al., "BGP/MPLS IP VPNs", draft-ietf-l3vpn-rfc2547bis-00.txt, May, 2003, Work in Progress. [RFC2858] Bates, T., et. al., "Multiprotocol Extensions for BGP-4", RFC 2858, June 2000. [RFC3439] Bush, R. and D. Meyer, "Some Internet Architectural Guidelines and Philosophy", RFC 3439, December, 2002. [SAFI] http://www.iana.org/assignments/safi-namespace [VLPS] Kompella, K., et. al. "Virtual Private LAN Service", draft-ietf-l2vpn-vpls-bgp-00.txt, Work in Progress. [VPWS] Kompella, K. et.al. "Layer 2 VPNs Over Tunnels", draft-kompella-ppvpn-l2vpn-03.txt, April 2003. Work in Progress. Meyer, et. al. Section 15.1. [Page 22] INTERNET-DRAFT Expires: April 2004 October 2003 15.2. Informative References [IETFOL] https://www1.ietf.org/mailman/listinfo/routing-discussion [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March, 1997. [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 3", RFC 2026/BCP 9, October, 1996. [RFC2028] Hovey, R. and S. Bradner, "The Organizations Involved in the IETF Standards Process", RFC 2028/BCP 11, October, 1996. [RFC2434] Narten, T., and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 2434/BCP 26, October 1998. [RVBIB] http://www.routeviews.org/papers [WILLINGER2002] Willinger, W., and J. Doyle, "Robustness and the Internet: Design and evolution", 2002. Meyer, et. al. Section 15.2. [Page 23] INTERNET-DRAFT Expires: April 2004 October 2003 16. Editor's Address David Meyer Email: dmm@1-4-5.net 17. Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Meyer, et. al. Section 17. [Page 24]