TOC 
IS-IS Working GroupF. Wei
Internet-DraftY. Qin
Updates: 5301, 5304, 5310Z. Li
(if approved)China Mobile
Intended status: Standards TrackT. Li
Expires: December 17, 2010Cisco Systems, Inc.
 J. Dong
 Huawei Technologies
 June 15, 2010


Purge Originator Identification TLV for IS-IS
draft-ietf-isis-purge-tlv-03

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 LSP flooding does not change LSP contents, this TLV should propagate with the purge.

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

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents 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 December 17, 2010.

Copyright Notice

Copyright (c) 2010 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.  Requirements Language
3.  The Purge Originator Identification TLV
4.  Using the Dynamic Hostname TLV in Purges
5.  Security Considerations
6.  Functional Changes
7.  IANA Considerations
8.  Acknowledgments
9.  Normative References
§  Authors' Addresses




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1.  Introduction

The IS-IS [ISO 10589] (ISO, “Intermediate system to Intermediate system routeing information exchange protocol for use in conjunction with the Protocol for providing the Connectionless-mode Network Service (ISO 8473),” .) 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 observed several circumstances where an IS can improperly generate a purge. These are all due to implementation deficiencies or implementations that predate [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,” .) and generate a purge when they receive a corrupted LSP.



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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] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).



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3.  The Purge Originator Identification 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 that it received the purge from.

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 Purge Originator Identification 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 that the purge was received from. (optional)



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4.  Using the Dynamic Hostname TLV in Purges

This document also extends the use of the Dynamic hostname TLV (type 137) [RFC5301] (McPherson, D. and N. Shen, “Dynamic Hostname Exchange Mechanism for IS-IS,” October 2008.). This TLV MAY also be included in purges. This will further aid in the rapid identification of the system that generated the purge.

Implementations SHOULD include the Purge Originator Identification TLV in addition to the Dynamic hostname TLV.



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5.  Security Considerations

If the Purge Originator Identification TLV or the Dynamic hostname TLV is used in conjunction with IS-IS authentication mechanisms [RFC5304] (Li, T. and R. Atkinson, “IS-IS Cryptographic Authentication,” October 2008.)[RFC5310] (Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., and M. Fanto, “IS-IS Generic Cryptographic Authentication,” February 2009.), the purge LSP is constructed or modified as follows. First, the original contents of the LSP are removed, leaving only the LSP header, then the Purge Originator Identification TLV and/or the Dynamic hostname TLV are added, and then the IS-IS authentication TLV is added.

Legacy systems that implement [RFC5304] (Li, T. and R. Atkinson, “IS-IS Cryptographic Authentication,” October 2008.) or [RFC5310] (Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., and M. Fanto, “IS-IS Generic Cryptographic Authentication,” February 2009.) MUST discard purges with these additional TLVs. This is not thought to be a significant operational issue as the loss of purges is typically not critical.



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6.  Functional Changes

This document amends the behavior specified in [RFC5301] (McPherson, D. and N. Shen, “Dynamic Hostname Exchange Mechanism for IS-IS,” October 2008.), [RFC5304] (Li, T. and R. Atkinson, “IS-IS Cryptographic Authentication,” October 2008.) and [RFC5310] (Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., and M. Fanto, “IS-IS Generic Cryptographic Authentication,” February 2009.). ISs that receive purges with the Purge Originator Identification TLV or the Dynamic hostname TLV with valid authentication MUST NOT discard the PDU and SHOULD process it normally. The Purge Originator Identification TLV or Dynamic hostname TLV MUST NOT be removed from the purge prior to propagation. If multiple purges are received for the same LSP fragment, then the implementation MAY propagate any one of the purges.



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7.  IANA Considerations

RFC EDITOR NOTE: This section to be removed upon publication.

This document requests that IANA assign a code point for this TLV from the IS-IS 'TLV Codepoints Registry'.



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8.  Acknowledgments

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

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

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



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9. Normative References

[ISO 10589] ISO, “Intermediate system to Intermediate system 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 (TXT, HTML, XML).
[RFC5301] McPherson, D. and N. Shen, “Dynamic Hostname Exchange Mechanism for IS-IS,” RFC 5301, October 2008 (TXT).
[RFC5304] Li, T. and R. Atkinson, “IS-IS Cryptographic Authentication,” RFC 5304, October 2008 (TXT).
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., and M. Fanto, “IS-IS Generic Cryptographic Authentication,” RFC 5310, February 2009 (TXT).


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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