wdiff rfc7884.original rfc7884.txt


Internet Engineering Task Force (IETF)                      C. Pignataro
Internet-Draft
Request for Comments: 7884                                         Cisco
Intended status:
Category: Standards Track                                      M. Bhatia
Expires: October 31, 2016
ISSN: 2070-1721                                           Ionos Networks
                                                               S. Aldrin
                                                     Huawei Technologies
                                                            T. Ranganath
                                                                   Nokia
                                                          April 29,
                                                               July 2016

OSPF Extensions to Advertise Seamless Bidirectional Forwarding Detection
                     (S-BFD) Target Discriminators
                 draft-ietf-ospf-sbfd-discriminator-06

Abstract

   This document defines a new OSPF Router Information (RI) TLV that
   allows OSPF routers to flood the Seamless Bidirectional Forwarding
   Detection (S-BFD) discriminator Discriminator values associated with a target
   network identifier.  This mechanism is applicable to both OSPFv2 and
   OSPFv3.

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.

   Internet-Drafts are working documents an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list  It represents the consensus of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid the IETF community.  It has
   received public review and has been approved for a maximum publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of six months RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 31, 2016.
   http://www.rfc-editor.org/info/rfc7884.

Copyright Notice

   Copyright (c) 2016 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
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Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2 ....................................................3
      1.1. Relationship Between between OSPF and S-BFD . . . . . . . . . . .   3 ........................3
   2. Implementation  . . . . . . . . . . . . . . . . . . . . . . .   3 ..................................................3
      2.1. S-BFD Discriminator TLV . . . . . . . . . . . . . . . . .   3 ....................................4
      2.2. Flooding Scope  . . . . . . . . . . . . . . . . . . . . .   4 .............................................4
   3. Backward Compatibility  . . . . . . . . . . . . . . . . . . .   5 ..........................................5
   4. Security Considerations . . . . . . . . . . . . . . . . . . .   5 .........................................5
   5. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5 .............................................6
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7. References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1. ......................................................6
      6.1. Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2. .......................................6
      6.2. Informative References  . . . . . . . . . . . . . . . . .   6 .....................................6
   Acknowledgements ...................................................7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6 .................................................7

1.  Introduction

   Seamless Bidirectional Forwarding Detection (S-BFD), specified in
   [I-D.ietf-bfd-seamless-base],
   [RFC7880], is a simplified mechanism for using
   Bidirectional Forwarding Detection (BFD) BFD with many
   negotiations eliminated.  This is achieved by using four-octet 4-octet
   discriminators, unique within an administrative domain, to identify
   the Network
   Targets. network targets.  These S-BFD discriminators Discriminators can be advertised by
   the IGPs, and this document concerns itself with OSPF.  Specifically,
   this document defines a new TLV (named the S-BFD Discriminator TLV)
   to be carried within the OSPF Router Information (RI) Link State
   Advertisement (LSA) ([RFC7770]). [RFC7770].

   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].

1.1.  Relationship Between between OSPF and S-BFD

   This document, implicitly, document implicitly defines a relationship between OSPF and
   S-BFD.  S-BFD assigns one or more discriminators to each S-BFD
   reflector node.  OSPF, in turn, learns about these from S-BFD, S-BFD and
   floods them in the newly defined TLV.  After this information is
   flooded, it is stored in all the OSPF nodes such that S-BFD
   initiators can map out target nodes to target discriminators, discriminators and can
   therefore construct the S-BFD probe.

   When multiple S-BFD discriminators Discriminators are advertised, how a given
   discriminator is mapped to a specific use case is out of scope for
   this document.

2.  Implementation

   This extension makes use of the Router Information (RI) Opaque LSA,
   defined in [RFC7770] , [RFC7770], for both OSPFv2 [RFC2328] and OSPFv3
   [RFC5340], [RFC5340]
   by defining a new OSPF Router Information (RI) TLV: the S-BFD
   Discriminator TLV.

   The S-BFD Discriminator TLV is OPTIONAL.  Upon receipt of the TLV, a
   router may decide to install the S-BFD discriminator Discriminator in the BFD Target
   Identifier Table.
   target identifier table.

   In the presence of multiple instances of the OSPF/OSPFv3 RI OSPFv2/OSPFv3 Router
   Information LSA, the S-BFD discriminators Discriminators for an OSPF router are the
   union of all discriminators advertised in all instances of the S-BFD
   Discriminator TLV (see Section 2.1) in all advertised non-MaxAge OSPF RI
   Router Information LSAs.

2.1.  S-BFD Discriminator TLV

   The format of the S-BFD Discriminator TLV is as follows:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Type             |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Discriminator 1                       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    Discriminator 2 (Optional)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                               ...                             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    Discriminator n (Optional)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type - S-BFD Discriminator TLV Type (TBD [to be filled in by IANA]) (11)

   Length - Total This field represents the total length of the
      discriminator(s) that appear appears in the Value field, in octets.  Each
      discriminator is 4 octets, so the Length is 4 four times the number
      of discriminators included in the TLV.  There is no optional
      padding for this field.

   Discriminator(s) - The Value field of the TVL TLV includes the S-BFD
      network target discriminator Discriminator value or values.

   Routers that do not recognize the S-BFD Discriminator TLV Type will
   ignore the TLV [RFC7770], [RFC7770] and therefore will not learn S-BFD
   discriminators
   Discriminators via OSPF.

2.2.  Flooding Scope

   The S-BFD Discriminator TLV is advertised within OSPFv2 Router
   Information LSAs (Opaque type of 4 and Opaque ID of 0) or OSPFv3
   Router Information LSAs (function code of 12), which are defined in
   [RFC7770].  As such, elements of this procedure are inherited from
   those defined in [RFC7770].

   In OSPFv2, the

   The flooding scope is controlled by the opaque Opaque LSA type (as defined
   in [RFC5250]) and in OSPFv3, OSPFv2 and by the S1/S2 bits (as defined in [RFC5340]).
   [RFC5340]) in OSPFv3.  If the flooding scope is area local, then the
   S-BFD Discriminator TLV MUST be carried within an OSPFv2 type 10
   router information
   Router Information LSA or an OSPFV3 Router Information LSA with the
   S1 bit set and the S2 bit clear.  If the flooding scope is the entire
   IGP domain, then the S-BFD Discriminator TLV MUST be carried within
   an OSPFv2 type 11 Router Information LSA or OSPFv3 Router Information
   LSA with the S1 bit clear and the S2 bit set.

   When the S-BFD Reflector reflector is deactivated, the OSPF speaker advertising
   this
   a particular S-BFD discriminator Discriminator MUST originate a new Router
   Information LSA that no longer includes the corresponding S-BFD
   Discriminator TLV, provided there are other TLVs in the LSA.  If
   there are no other TLVs in the LSA, it MUST either send an empty
   Router Information LSA or purge it by prematurely ageing aging it.

   For intra-area reachability, the S-BFD Discriminator TLV information
   regarding a specific target identifier is only considered current and
   useable
   usable when the router advertising this that information is itself
   reachable via OSPF calculated paths in the same area of the LSA in
   which the S-BFD Discriminator TLV appears.  In the case of domain-
   wide
   domain-wide flooding, i.e., where the originator is sitting in a
   remote area, the mechanism described in section Section 5 of [RFC5250] should
   be used.

   Although the S-BFD discriminators Discriminators may change when enabling the S-BFD
   functionality or via an explicit configuration event, such changes
   are expected to occur very rarely.  Such a change changes in the information will
   require that the S-BFD Discriminator TLV in OSPF to be advertised.

   A change in information in the S-BFD Discriminator TLV MUST NOT
   trigger any SPF computation computations at a receiving router.

3.  Backward Compatibility

   The S-BFD Discriminator TLV defined in this document does not
   introduce any interoperability issues.

   A router not supporting the S-BFD Discriminator TLV will just
   silently ignore the TLV TLV, as specified in [RFC7770].

4.  Security Considerations

   This document defines OSPF extensions to distribute the S-BFD
   discriminator
   Discriminator within an administrative domain.  Hence  Hence, the security
   of
   the S-BFD discriminator Discriminator distribution relies on the security of OSPF.

   OSPF provides no encryption mechanism for protecting the privacy of
   LSAs and, in particular, the privacy of the S-BFD discriminator Discriminator
   advertisement information.  This however  However, this is not a concern concern, as there
   isn't any need to hide the discriminator Discriminator value that can be used to
   reach the Reflectors. reflectors.

5.  IANA Considerations

   IANA has defined a registry for TLVs carried in the Router
   Information LSA defined in [RFC7770].  IANA needs to assign has assigned a new TLV
   codepoint (11) for the S-BFD Discriminator TLV carried within in the "OSPF Router
   Information LSA. (RI) TLVs" registry.

        Value      TLV Name                 Reference
        -----      --------                 ----------
        TBD
        11         S-BFD                    (this document)                    RFC 7884
                   Discriminator

6.  Acknowledgements

   The authors would like to thank Nobo Akiya, Les Ginsberg, Mach Chen
   and Peter Psenak for insightful comments and useful suggestions.

7.  References

7.1.

6.1.  Normative References

   [I-D.ietf-bfd-seamless-base]
              Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J.
              Networks, "Seamless Bidirectional Forwarding Detection
              (S-BFD)", draft-ietf-bfd-seamless-base-09 (work in
              progress), April 2016.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328,
              DOI 10.17487/RFC2328, April 1998,
              <http://www.rfc-editor.org/info/rfc2328>.

   [RFC5340]  Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
              <http://www.rfc-editor.org/info/rfc5340>.

   [RFC7770]  Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
              S. Shaffer, "Extensions to OSPF for Advertising Optional
              Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
              February 2016, <http://www.rfc-editor.org/info/rfc7770>.

7.2.

   [RFC7880]  Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S.
              Pallagatti, "Seamless Bidirectional Forwarding Detection
              (S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016,
              <http://www.rfc-editor.org/info/rfc7880>.

6.2.  Informative References

   [RFC5250]  Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The
              OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250,
              July 2008, <http://www.rfc-editor.org/info/rfc5250>.

Acknowledgements

   The authors would like to thank Nobo Akiya, Les Ginsberg, Mach Chen,
   and Peter Psenak for insightful comments and useful suggestions.

Authors' Addresses

   Carlos Pignataro
   Cisco Systems, Inc.

   Email: cpignata@cisco.com

   Manav Bhatia
   Ionos Networks

   Email: manav@ionosnetworks.com

   Sam Aldrin
   Huawei Technologies

   Email: aldrin.ietf@gmail.com

   Trilok Ranganath
   Nokia

   Email: trilok.ranganatha@nokia.com