Advertising Seamless Bidirectional Forwarding Detection (S-BFD) Discriminators in IS-IS
draft-ietf-isis-sbfd-discriminator-02

Networking Working Group                                     L. Ginsberg
Internet-Draft                                                  N. Akiya
Intended status: Standards Track                           Cisco Systems
Expires: September 3, 2015                                       M. Chen
                                                                  Huawei
                                                           March 2, 2015

               Advertising S-BFD Discriminators in IS-IS
               draft-ietf-isis-sbfd-discriminator-02.txt

Abstract

   This document defines a means of advertising one or more S-BFD
   Discriminators using the IS-IS Router Capability TLV.

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].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on September 3, 2015.

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   document authors.  All rights reserved.

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   publication of this document.  Please review these documents

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   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.   Encoding Format  . . . . . . . . . . . . . . . . . . . . . .   2
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   [S-BFD] defines a simplified mechanism to use Bidirectional
   Forwarding Detection (BFD)[RFC5880].  This mechanism depends on
   network nodes knowing the BFD discriminators which each node in the
   network has reserved for this purpose.  Use of the Intermediate
   System to Intermediate System (IS-IS)[IS-IS] protocol is one possible
   means of advertising these discriminators.

2.  Encoding Format

   The IS-IS Router CAPABILITY TLV as defined in [RFC4971] will be used
   to advertise S-BFD discriminators.  A new sub-TLV is defined as
   described below.  S-BFD Discriminators sub-TLVs are formatted as
   specified in [RFC5305].

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                                                  No. of octets
                 +-----------------------------+
                 | Type (to be assigned by     |     1
                 | IANA - suggested value 20)  |
                 +-----------------------------+
                 | Length (multiple of 4)      |     1
                 +-----------------------------+
                 | Discriminator Value(s)      |     4/Discriminator
                 :                             :
                 +-----------------------------+

   Inclusion of the S-BFD Discriminators sub-TLV in a Router Capability
   TLV is optional.  Multiple S-BFD Discriminators sub-TLVs MAY be
   advertised by an IS.  When multiple S-BFD discriminators are
   advertised how a given discriminator is mapped to a specific use case
   is out of scope for this document.

   S-BFD discriminator advertisements MAY be flooded within an area or
   throughout the domain using the procedures specified in [RFC4971].
   The appropriate flooding scope depends on the intended use of S-BFD.
   If S-BFD use will be exclusively within a Level-1 area then area
   scope is appropriate.  If S-BFD usage will span different L1 areas
   then domain scope is appropriate.

3.  IANA Considerations

   This document requires the definition of a new sub-TLV in the Sub-
   TLVs for TLV 242 registry.  The value written below is a suggested
   value subject to assignment by IANA.

    Value  Description
    ----  ---------------------
     20    S-BFD Discriminators

4.  Security Considerations

   Security concerns for IS-IS are addressed in [IS-IS], [RFC5304], and
   [RFC5310].  Introduction of the S-BFD Discriminators sub-TLV
   introduces no new security risks for IS-IS.

   Advertisement of the S-BFD discriminators does make it possible for
   attackers to initiate S-BFD sessions using the advertised
   information.  The vulnerabilities this poses and how to mitigate them
   are discussed in the Security Considerations section of [S-BFD].

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5.  Acknowledgements

   The authors wish to thank Sam Aldrin, Manav Bhatia, and Carlos
   Pignataro for input essential to defining the needed functionality.

6.  Normative References

   [IS-IS]    "Intermediate system to Intermediate system intra-domain
              routeing information exchange protocol for use in
              conjunction with the protocol for providing the
              connectionless-mode Network Service (ISO 8473), ISO/IEC
              10589:2002, Second Edition.", Nov 2002.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4971]  Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate
              System to Intermediate System (IS-IS) Extensions for
              Advertising Router Information", RFC 4971, July 2007.

   [RFC5304]  Li, T. and R. Atkinson, "IS-IS Cryptographic
              Authentication", RFC 5304, October 2008.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, October 2008.

   [RFC5310]  Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
              and M. Fanto, "IS-IS Generic Cryptographic
              Authentication", RFC 5310, February 2009.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, June 2010.

   [S-BFD]    "Seamless Bidirectional Forwarding Detection (S-BFD),
              draft-ietf-bfd-seamless-base-04(work in progress)",
              January 2015.

Authors' Addresses

   Les Ginsberg
   Cisco Systems
   510 McCarthy Blvd.
   Milpitas, CA  95035
   USA

   Email: ginsberg@cisco.com

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   Nobo Akiya
   Cisco Systems

   Email: nobo@cisco.com

   Mach(Guoyi) Chen
   Huawei

   Email: mach.chen@huawei.com

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