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Internet Engineering Task Force (IETF)                            F. WeiRequest for Comments: 6232                                        Y. QinUpdates:5301,5304,5310                                          Z. LiCategory: Standards Track                                   China MobileISSN: 2070-1721                                                    T. Li                                                     Cisco Systems, Inc.                                                                 J. Dong                                                     Huawei Technologies                                                                May 2011Purge Originator Identification TLV for IS-ISAbstract   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 updatesRFC 5301,RFC 5304, andRFC 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 inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc6232.Wei, et al.                  Standards Track                    [Page 1]

RFC 6232           Purge Originator Identification TLV          May 2011Copyright Notice   Copyright (c) 2011 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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 Contents1. Introduction ....................................................22. Requirements Language ...........................................33. The Purge Originator Identification (POI) TLV ...................34. Using the Dynamic Hostname TLV in Purges ........................35. Security Considerations .........................................46. IANA Considerations .............................................47. Acknowledgments .................................................48. Normative References ............................................41.  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 20112.  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 20115.  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 2011Authors' 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.comWei, et al.                  Standards Track                    [Page 6]