Network Working Group Robert Raszuk (Editor) Internet Draft Cisco Systems, Inc Category: Standards Track June 2003 Expires: December 2003 OSPF Extensions for BGP Peer Discovery draft-raszuk-ospf-bgp-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 proposed an extension to OSPF Router Information LSA [LINDEM1] to distribute selected information about BGP process on a router to other routers in the same area or in the same domain. 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 OSPF 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. In IBGP Auto Mesh draft [IBGP-AM] we propose the automation of this task for IBGP sessions. As a distribution of required information OSPF [RFC2328] native flooding is being proposed. The information required to be flooded is static and can change only by operator's manual configuration. 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 OSPF to be flooded over such a new transport. 3. The BGP Auto Discovery TLV BGP Auto Discovery TLV is proposed to be flooded inside OSPF Router Information LSA. The format of OSPF Router Information LSA is indicated for reference in Figure 1 as proposed in [LINDEM1] 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS age | Options | 10 or 11 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 4 | 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS sequence number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS checksum | length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +- TLVs -+ | ... | Raszuk R. Expires Dec 2003 [Page 2] Internet Draft OSPF Ext for IBGP Auto Mesh June 2003 Figure 1. OSPF Router Information LSA For the application of distribution of BGP Auto Discovery TLV only area wise flooding scope (code 10) and domain wide flooding scope (code 11) are applicable. As described in IBGP Auto Mesh document [IBGP-AM] BGP Auto Discovery TLV will have the format presented in figure 2. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Old BGP Identifier sub-TLV (opt) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1. BGP Auto Discovery TLV Type One octet set to 2 (to be confirmed). Length One octet indicating the length of the TLV Control Flags related to IGP operation: Symbol Capabilities F Flooding scope D Down Bit Reserved Set to all zeros "F" {flooding} flooding scope of this TLV, when set domain wide flooding scope is required (type 11), when not set TLV should not be flooded into other areas or levels (type 10). Default "F" not set indicating area wide flooding only (type 10). "D" {down} down bit is not relevant to OSPF and should be ignored by Raszuk R. Expires Dec 2003 [Page 3] Internet Draft OSPF Ext for IBGP Auto Mesh June 2003 OSPF. It is present in the BGP Auto Discovery TLV to achieve identical encapsulation syntax independent from flooding protocol being selected by the operator. The specific information and encoding of BGP sub-TLVs is discussed in [IBGP-AM]. 4. Operation It should be important to emphasize the fact that OSPF 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 cache. BGP component will also inform OSPF about required flooding scope for it's information. OSPF role in new information interpretation is limited to selectively pass BGP Auto Discovery TLV to BGP component of the router. It is assumed that all global LSA comparisons will still take place. On the other hand it is not required that OSPF 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 itself much less CPU intensive. Forced reflooding should only take place based on the manual configuration change. 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 OSPF. 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 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. Raszuk R. Expires Dec 2003 [Page 4] Internet Draft OSPF Ext for IBGP Auto Mesh June 2003 6. IANA Considerations A new opaque LSA type for OSPF Router Information LSA will need to be assigned by IANA. Additionally, IANA will need to have registries for the OSPF Router Information opaque LSA TLVs. The TLV assignee will be responsible for allocation of any sub-TLVs for the IANA assigned TLV. 7. Security Considerations It is highly encouraged to use existing OSPF security mechanism when transporting BGP Auto Discovery TLV [RFC2328]. While addition of new information does not present any additional risks injection of not authorized OSPF Router Information LSAs containing unreal BGP Auto Discovery TLVs could require an implementation of additional filtering before attempting to establish IBGP sessions. 8. Acknowledgments I would like to express special thanks to Abhay Roy & Peter Psenak 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. 10. Informative References [IBGP-AM] Raszuk, R., "IBGP Auto Mesh", draft-raszuk-ibgp-auto- mesh-00.txt, June 2003 [LINDEM1] Lindem, A. at all, "Extensions to OSPF for Advertising Optional Router Capabilities", draft-lindem-ospf-cap-00.txt, May 2003 [RFC2328] J. Moy. OSPF version 2. Technical Report RFC 2328, Internet Engineering Task Force, 1998. Raszuk R. Expires Dec 2003 [Page 5] Internet Draft OSPF 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 OSPF Ext for IBGP Auto Mesh June 2003 14. Full Copyright Notice Copyright (C) The Internet Society (2002). 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. Raszuk R. Expires Dec 2003 [Page 7]