IS-IS BFD-Enabled TLV
RFC 6213
Document | Type | RFC - Proposed Standard (April 2011; No errata) | |
---|---|---|---|
Authors | Christian Hopps , Les Ginsberg | ||
Last updated | 2015-10-14 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 6213 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Stewart Bryant | ||
Send notices to | (None) |
Internet Engineering Task Force (IETF) C. Hopps Request for Comments: 6213 L. Ginsberg Category: Standards Track Cisco Systems ISSN: 2070-1721 April 2011 IS-IS BFD-Enabled TLV Abstract This document describes a type-length-value (TLV) for use in the IS- IS routing protocol that allows for the proper use of the Bidirectional Forwarding Detection (BFD) protocol. There exist certain scenarios in which IS-IS will not react appropriately to a BFD-detected forwarding plane failure without use of either this TLV or some other method. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6213. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Hopps & Ginsberg Standards Track [Page 1] RFC 6213 IS-IS BFD-Enabled TLV April 2011 Table of Contents 1. Introduction ....................................................2 1.1. Requirements Language ......................................2 2. The Problem .....................................................2 3. The Solution ....................................................3 3.1. State Definitions ..........................................3 3.2. Adjacency Establishment and Maintenance ....................4 3.3. Advertisement of Topology-Specific IS Neighbors ............4 4. Transition ......................................................4 5. Graceful Restart ................................................5 6. The BFD-Enabled TLV .............................................5 7. Security Considerations .........................................6 8. IANA Considerations .............................................6 9. Acknowledgements ................................................6 10. Normative References ...........................................7 1. Introduction The Bidirectional Forwarding Detection (BFD) protocol [RFC5880] is a protocol that allows for detection of a forwarding plane failure between two routers. A router can use [RFC5880] to validate that a peer router's forwarding ability is functioning. One specific application of BFD as described in [RFC5882] is to verify the forwarding ability of an IS-IS [RFC1195] router's adjacencies; however, the method described in [RFC5882] does not allow for certain failure scenarios. We will define a TLV that will allow for proper response to the detection of all forwarding failures where the use of BFD is employed with IS-IS. 1.1. Requirements Language 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 [RFC2119]. 2. The Problem We observe that, in order to allow for mixed use (i.e., some routers running BFD and some not), [RFC5882] does not require a BFD session be established prior to the establishment of an IS-IS adjacency. Thus, if a router A has neighbors B and C, and B does not support BFD, A would still form adjacencies with B and C, and it would only establish a BFD session with C. Hopps & Ginsberg Standards Track [Page 2] RFC 6213 IS-IS BFD-Enabled TLV April 2011 The problem with this solution is that it assumes that the transmission and receipt of IS-IS Hellos (IIHs) shares fate with forwarded data packets. This is not a fair assumption to make given that the primary use of BFD is to protect IPv4 (and IPv6) forwarding, and IS-IS does not utilize IPv4 or IPv6 for sending or receiving itsShow full document text