Network Working Group Robert Raszuk (Editor) Internet Draft Cisco Systems, Inc Category: Standards Track June 2003 Expires: December 2003 ISIS Extensions for BGP Peer Discovery draft-raszuk-isis-peer-discovery-00.txt Status of this Memo 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. Internet Drafts may be updated, replaced, or obsolete by other documents at any time. It is not appropriate to use Internet Drafts as reference material or to cite them other than as a "working draft" or "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. Abstract This document proposes an extension to IS-IS protocol [ISO10589] to support BGP peer auto discovery. We propose the addition of new information that an Intermediate System can flood in it's LSPDU. Such information is required for network based auto discovery of IBGP peers as described in [IBGP-AM]. Raszuk R. Expires Dec 2003 [Page 1] Internet Draft ISIS Ext for IBGP Auto Mesh June 2003 1. Specification of Requirements 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 [RFC2119]. 2. Introduction Today all BGP peering configuration is manual and requires action on both sides of any given peering. In IBGP Auto Mesh draft [IBGP-AM] we propose the automation of this task for IBGP sessions. As a distribution of required information IS-IS [ISO10589] native flooding layer is being proposed for reuse. The information required to be flooded is static and can change only by operator's manual configuration action. It is envisioned that in the future when new and better approaches for flooding information are available and deployed BGP Auto Discovery TLV could also be migrated from ISIS to such a new transport. 3. The BGP Auto Discovery TLV BGP Auto Discovery TLV is an IS-IS TLV of type code 243 (to be confirmed). The format of BGP Auto Discovery TLV is indicated for reference in Figure 1 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV Type | Length | FLOODING RESERVED |F|D| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BGP Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | FRAG | BGP RESERVED | 16 bit CHECKSUM | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Autonomous System(s) or confederation sub-AS(s) sub-TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4/IPv6 Peering Address sub-TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AFI/SAFI for mesh topologies sub-TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AFI/SAFI for reflection topologies sub-TLV | Raszuk R. Expires Dec 2003 [Page 2] Internet Draft ISIS Ext for IBGP Auto Mesh June 2003 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Old BGP Identifier sub-TLV (opt) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1. BGP Auto Discovery TLV Type - Code 243 (to be confirmed) Length - Total length in octets Control Flags related to IGP operation: Symbol Capabilities F Flooding scope D Down Bit "F" {flooding} flooding scope of this TLV, when set domain wide flooding scope is required, when not set TLV should not be flooded into other areas or levels. Default not set indicating area/level wide flooding only. "D" {down} down bit set by IGP when leaked to other levels. BGP Auto Discovery TLV can be contained in any LSP fragment. It also can be repeated. BGP itself will take all necessary filtering/update actions on reception of this information from ISIS. The minimum TLV length can be 10 octets. When a size of the TLV reaches 255 octets BGP will fragment the TLV. A special "FRAG" 4 bit counter has been allocated in the BGP Control Information section for unlikely cases where BGP Auto Discovery TLV needs to be splitted across multiple TLVs for a given BGP speaker. Fragmentation should be fully transparent to ISIS component. The specific information and encoding of BGP sub-TLVs is discussed in [IBGP-AM]. Raszuk R. Expires Dec 2003 [Page 3] Internet Draft ISIS Ext for IBGP Auto Mesh June 2003 4. Operation It should be important to emphasize the fact that ISIS interaction with the new information is to remain minimal. BGP component will prepare the necessary information to be flooded as well as keep the received information in it's own data structure (cache). BGP component will also inform ISIS about required flooding scope for it's information by setting the F bit. It is assumed that all global LSP comparison will still take place. On the other hand it is not required that ISIS will try to parse and compare the TLV itself and based on the result initiate BGP notification or not. Added checksum field should make comparison done by BGP much less CPU intensive. Forced reflooding should only take place based on the manual configuration change of session related parameters. During normal network operation when BGP configuration related to peer maintenance is constant BGP Auto Discovery TLV should not cause any extra processing or flooding for ISIS. 5. Deployment Considerations The new proposed data to be flooded has an informational character. Routers which do not understand new information will not be able to participate in the IBGP auto mesh. Deployment of new code which supports new information can be incremental. Also enabling information distribution itself can also have an incremental character. It should be up to operator's decision to switch from informational use of BGP Auto Discovery TLV to operational IBGP auto mesh benefits. 6. IANA Considerations A new ISIS TLV type will need to be assigned by IANA. The TLV assignee will be responsible for allocation of any sub-TLVs for the IANA assigned TLV. Raszuk R. Expires Dec 2003 [Page 4] Internet Draft ISIS Ext for IBGP Auto Mesh June 2003 7. Security Considerations It is highly encouraged to use existing ISIS security mechanism when transporting BGP Auto Discovery TLV. While addition of new information does not present any additional risks, potential consequences of injection of not authorized BGP Auto Discovery TLVs into routing domain could by minimized by implementation of additional filtering before attempting to establish IBGP sessions. 8. Acknowledgments I would like to express special thanks to Stefano Previdi, Steven Luong & Abhay Roy for their comments. 9. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [RFC2434] Narten, T., Alvestrand, H., "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 2434, October 1998. [ISO10589] "Intermediate System to Intermediate System Intra-Domain Routing Exchange Protocol for use in Conjunction with the Protocol for Providing the Connectionless-mode Network Service (ISO8473)" [Also republished as RFC 1142] [RFC2966] T. Li, T. Przygienda, H. Smit, "Domain-wide Prefix Distribution with Two-Level IS-IS", October 2000. 10. Informative References [IBGP-AM] Raszuk, R., "IBGP Auto Mesh", draft-raszuk-ibgp-auto- mesh-00.txt, June 2003 Raszuk R. Expires Dec 2003 [Page 5] Internet Draft ISIS Ext for IBGP Auto Mesh June 2003 11. Authors' Addresses Robert Raszuk Cisco Systems, Inc. Al. Jerozolimskie 146C 02-305 Warsaw, Poland Email: rraszuk@cisco.com 12. IPR Notices 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. 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. 13. Terms of Use Cisco has a pending patent which relates to the subject matter of this Internet Draft. If a standard relating to this subject matter is adopted by IETF and any claims of any issued Cisco patents are necessary for practicing this standard, any party will be able to obtain a license from Cisco to use any such patent claims under openly specified, reasonable, non-discriminatory terms to implement and fully comply with the standard. Raszuk R. Expires Dec 2003 [Page 6] Internet Draft ISIS Ext for IBGP Auto Mesh June 2003 14. Full Copyright Notice Copyright (C) The Internet Society (2002). All Rights Reserved. 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