--- 1/draft-ietf-bfd-multihop-01.txt 2006-02-04 22:51:12.000000000 +0100 +++ 2/draft-ietf-bfd-multihop-02.txt 2006-02-04 22:51:13.000000000 +0100 @@ -1,19 +1,19 @@ Network Working Group D. Katz Internet Draft Juniper Networks D. Ward Cisco Systems -Expires: August, 2005 February, 2005 +Expires: September, 2005 March, 2005 BFD for Multihop Paths - draft-ietf-bfd-multihop-01.txt + draft-ietf-bfd-multihop-02.txt Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, or will be disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that @@ -26,21 +26,21 @@ 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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright Notice - Copyright (C) The Internet Society (2004). All Rights Reserved. + Copyright (C) The Internet Society (2005). All Rights Reserved. Abstract This document describes the use of the Bidirectional Forwarding Detection protocol (BFD) over multihop paths, including unidirectional links. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", @@ -56,41 +56,41 @@ BFD can also be useful on arbitrary paths between systems, which may span multiple network hops and follow unpredictable paths. Furthermore, a pair of systems may have multiple paths between them that may overlap. This document describes methods for using BFD in such scenarios. 2. Issues There are two primary issues in the use of BFD for multihop paths. - The first is security and spoofing; the one-hop spec describes a + The first is security and spoofing; [BFD-1HOP] describes a lightweight method of avoiding spoofing by requiring a TTL/hop limit of 255 on both transmit and receive, but this obviously does not work across multiple hops. The utilization of BFD authentication addresses this issue. The more subtle issue is that of demultiplexing multiple BFD sessions between the same pair of systems to the proper BFD session. In particular, the first BFD packet received for a session may carry a Your Discriminator value of zero, resulting in ambiguity as to which session the packet should be associated. Once the discriminator values have been exchanged, all further packets are demultiplexed to the proper BFD session solely by the contents of the Your Discriminator field. - The one-hop specification addresses this by requiring that multiple - sessions traverse independent physical or logical links--the first - packet is demultiplexed based on the link over which it was received. - In the more general case, this scheme cannot work, as two paths over - which BFD is running may overlap to an arbitrary degree (including - the first and/or last hop.) + [BFD-1HOP] addresses this by requiring that multiple sessions + traverse independent physical or logical links--the first packet is + demultiplexed based on the link over which it was received. In the + more general case, this scheme cannot work, as two paths over which + BFD is running may overlap to an arbitrary degree (including the + first and/or last hop.) 3. Demultiplexing Packets There are a number of possibilities for addressing the demultiplexing issue which may be used, depending on the application. 3.1. Totally Arbitrary Paths It may be desired to use BFD for liveness detection over paths for which no part of the route is known (or if known, may not be stable.) @@ -156,31 +156,28 @@ 4. Authentication By their nature, multihop paths expose BFD to spoofing. Implementations of BFD SHOULD utilize authentication over multihop paths to help mitigate denial-of-service attacks. Normative References [BFD] Katz, D., and Ward, D., "Bidirectional Forwarding Detection", - draft-ietf-bfd-base-01.txt, February, 2005. + draft-ietf-bfd-base-02.txt, March, 2005. [BFD-1HOP] Katz, D., and Ward, D., "BFD for IPv4 and IPv6 (Single - Hop)", draft-ietf-bfd-v4v6-1hop-01.txt, February, 2005. + Hop)", draft-ietf-bfd-v4v6-1hop-02.txt, March, 2005. [BFD-MPLS] Aggarwal, R., and Kompella, K., "BFD for MPLS LSPs", draft-ietf-bfd-mpls-01.txt, February, 2005. - [GTSM] Gill, V., et al, "The Generalized TTL Security Mechanism - (GTSM)", RFC 3682, February 2004. - [KEYWORD] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [OSPFv2] Moy, J., "OSPF Version 2", RFC 2328, April 1998. [OSPFv3] Coltun, R., et al, "OSPF for IPv6", RFC 2740, December 1999. Security Considerations No additional security issues are raised in this document beyond @@ -197,33 +194,32 @@ Dave Ward Cisco Systems 170 W. Tasman Dr. San Jose, CA 95134 USA Phone: +1-408-526-4000 Email: dward@cisco.com Changes from the previous draft - No changes were made other than updating references and boilerplate - language. + No changes were made other than updating references. Full Copyright Notice - Copyright (C) The Internet Society (2004). This document is subject + Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. - This document expires in August, 2005. + This document expires in September, 2005.