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.

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.

   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).

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.

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.

   [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.

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