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rfc:rfc6232

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.

Wei, et al. Standards Track [Page 1] 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).

Wei, et al. Standards Track [Page 2] 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.

Wei, et al. Standards Track [Page 3] 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.

Wei, et al. Standards Track [Page 4] 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.

Wei, et al. Standards Track [Page 5] 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: weifang@chinamobile.com
 Yue Qin
 China Mobile
 No. 29, Financial Street, Xicheng District
 Beijing  100032
 P.R. China
 EMail: qinyue@chinamobile.com
 Zhenqiang Li
 China Mobile
 Unit2, Dacheng Plaza, No. 28 Xuanwumenxi Ave., Xuanwu District
 Beijing  100053
 P.R. China
 EMail: lizhenqiang@chinamobile.com
 Tony Li
 Cisco Systems, Inc.
 170 W. Tasman Dr.
 San Jose, CA  95134
 USA
 EMail: tony.li@tony.li
 Jie Dong
 Huawei Technologies
 KuiKe Building, No. 9 Xinxi Rd., Haidian District
 Beijing  100085
 P.R. China
 EMail: dongjie_dj@huawei.com

Wei, et al. Standards Track [Page 6]

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