Internet Engineering Task Force (IETF)                            F. Wei
Request for Comments: 6232                                        Y. Qin
Updates: 5301, 5304, 5310                                          Z. Li
Category: Standards Track                                   China Mobile
ISSN: 2070-1721                                                    T. Li
                                                    Cisco Systems, Inc.
                                                                J. Dong
                                                    Huawei Technologies
                                                               May 2011


            Purge Originator Identification TLV for IS-IS

Abstract

  At present, an IS-IS purge does not contain any information
  identifying the Intermediate System (IS) that generates the purge.
  This makes it difficult to locate the source IS.

  To address this issue, this document defines a TLV to be added to
  purges to record the system ID of the IS generating it.  Since normal
  Link State Protocol Data Unit (LSP) flooding does not change LSP
  contents, this TLV should propagate with the purge.

  This document updates RFC 5301, RFC 5304, and RFC 5310.

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/rfc6232.












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RFC 6232           Purge Originator Identification TLV          May 2011


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.

Table of Contents

  1. Introduction ....................................................2
  2. Requirements Language ...........................................3
  3. The Purge Originator Identification (POI) TLV ...................3
  4. Using the Dynamic Hostname TLV in Purges ........................3
  5. Security Considerations .........................................4
  6. IANA Considerations .............................................4
  7. Acknowledgments .................................................4
  8. Normative References ............................................4

1.  Introduction

  The IS-IS [ISO-10589] routing protocol has been widely used in large-
  scale IP networks because of its strong scalability and fast
  convergence.

  The IS-IS protocol floods purges throughout an area, regardless of
  which IS initiated the purge.  If a network operator would like to
  investigate the cause of the purge, it is difficult to determine the
  origin of the purge.  At present, the IS-IS protocol has no mechanism
  to locate the originator of a purge.  To address this problem, this
  document defines a TLV to be added to purges to record the system ID
  of the IS generating the purge.

  Field experience has shown several circumstances where an IS can
  improperly generate a purge.  These are all due to implementation
  deficiencies or implementations that predate [ISO-TC1] and generate a
  purge when they receive a corrupted Link State Protocol Data Unit
  (LSP).






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RFC 6232           Purge Originator Identification TLV          May 2011


2.  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 [RFC2119].

3.  The Purge Originator Identification (POI) TLV

  This document defines a TLV to be included in purges.  If an IS
  generates a purge, it SHOULD include this TLV in the purge with its
  own system ID.  If an IS receives a purge that does not include this
  TLV, then it SHOULD add this TLV with both its own system ID and the
  system ID of the IS from which it received the purge.  This allows
  ISs receiving purges to log the system ID of the originator, or the
  upstream source of the purge.  This makes it much easier for the
  network administrator to locate the origin of the purge and thus the
  cause of the purge.  Similarly, this TLV is helpful to developers in
  lab situations.

  The POI TLV is defined as:

     CODE - 13

     LENGTH - total length of the value field.

     VALUE -

        Number of system IDs carried in this TLV (1 octet) -- only the
        values 1 and 2 are defined.

        System ID of the Intermediate System that inserted this TLV.

        System ID of the Intermediate System from which the purge was
        received (optional).

  The POI TLV SHOULD be found in all purges and MUST NOT be found in
  LSPs with a non-zero Remaining Lifetime.

4.  Using the Dynamic Hostname TLV in Purges

  This document also extends the use of the Dynamic hostname TLV
  (type 137) [RFC5301] to further aid in the rapid identification of
  the system that generated the purge.  This TLV MAY be included in
  purges.  Implementations SHOULD include one instance of the Dynamic
  hostname TLV if the POI TLV is included.  Only the local hostname
  should be inserted.





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RFC 6232           Purge Originator Identification TLV          May 2011


5.  Security Considerations

  Use of the extensions defined here, with authentication as defined in
  [RFC5304] or [RFC5310], will result in the discarding of purges by
  legacy systems that are in strict conformance with either of those
  RFCs.  This may compromise the correctness/consistency of the routing
  database unless all ISs in the network support these extensions.
  Therefore, all implementations in a domain implementing
  authentication MUST be upgraded to receive the POI TLV before any IS
  is allowed to generate a purge with the POI TLV.

  More interactions between the POI TLV, the Dynamic hostname TLV, and
  the Authentication TLV are described in [RFC6233].

6.  IANA Considerations

  IANA has assigned code point 13 for the 'Purge Originator
  Identification' TLV from the IS-IS 'TLV Codepoints' registry.  The
  additional values for this TLV should be IIH:n, LSP:y, SNP:n, and
  Purge:y.

7.  Acknowledgments

  Many thanks to Adrian Farrel and Daniel King for their comments to
  improve this document and move it forward.

  The first version of this document was mainly composed by
  Lianyuan Li.

  Acknowledgments are given to the discussion in the mailing list.
  Some improvements to this document are based on the discussion.

8.  Normative References

  [ISO-10589]  ISO, "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.

  [ISO-TC1]    ISO, "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) --
               Technical Corrigendum 1", ISO/IEC 10589:1992/
               Cor.1:1993.





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RFC 6232           Purge Originator Identification TLV          May 2011


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

  [RFC5301]    McPherson, D. and N. Shen, "Dynamic Hostname Exchange
               Mechanism for IS-IS", RFC 5301, October 2008.

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

  [RFC6233]    Li, T. and L. Ginsberg, "IS-IS Registry Extension for
               Purges", RFC 6233, May 2011.




































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RFC 6232           Purge Originator Identification TLV          May 2011


Authors' Addresses

  Fang Wei
  China Mobile
  No. 29, Financial Street, Xicheng District
  Beijing  100032
  P.R. China

  EMail: [email protected]


  Yue Qin
  China Mobile
  No. 29, Financial Street, Xicheng District
  Beijing  100032
  P.R. China

  EMail: [email protected]


  Zhenqiang Li
  China Mobile
  Unit2, Dacheng Plaza, No. 28 Xuanwumenxi Ave., Xuanwu District
  Beijing  100053
  P.R. China

  EMail: [email protected]


  Tony Li
  Cisco Systems, Inc.
  170 W. Tasman Dr.
  San Jose, CA  95134
  USA

  EMail: [email protected]


  Jie Dong
  Huawei Technologies
  KuiKe Building, No. 9 Xinxi Rd., Haidian District
  Beijing  100085
  P.R. China

  EMail: [email protected]






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