IS-IS Working Group F. Wei Internet-Draft Y. Qin Intended status: Standards Track L. Li Expires: September 6, 2010 Z. Li China Mobile March 5, 2010 New TLV for Purge Packet in ISIS draft-wei-isis-tlv-01 Abstract At present the purge packet does not contain information of the source router generating it. Thus under the circumstance of purge packet propagation, it is difficult to tracback and locate the source router. To address the problem, this document proposes to add a new TLV in purge packet to record the system ID of the IS generating it. This TLV should not be changed in purge packets sent by other routers. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 6, 2010. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the Wei, et al. Expires September 6, 2010 [Page 1] Internet-Draft New TLV for Purge Packet in ISIS March 2010 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 BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 3. Cases to generate purge packet . . . . . . . . . . . . . . . . 5 4. Proposed New TLV in Purge Packet . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. Informative References . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Wei, et al. Expires September 6, 2010 [Page 2] Internet-Draft New TLV for Purge Packet in ISIS March 2010 1. Introduction ISIS [ISO 10589] routing protocol has been widely used large-scale IP networks because of its strong scalability and fast speed of convergence. ISIS is a kind of link-state routing protocols by flooding the LSP to advertise route network widely. When router A receives a corrupted LSP from router B, which may be caused by router B or the link between them, router A should generate a corruptedLSPReceived event and then discard the corrupted LSP according to [ISO 10589]. Some implementations, however, will remove routes to router B, generate purge packet and flood it to the whole network. The purge packet informs other routers in the network that the LSP is wrong and the route to router B is not reachable. Other routers receiving the purge packet will do the same operation: delete the route and flood the purge packet. The route will be recovered until router B generates a new LSP to inform the whole network. if again, the LSP is damaged when it receives Router A, the above procedure will repeat and the whole network will flap. Such phenomenon was observed in China Mobile's network consisting of hundreds of routers in 20007, 5 years after the publication of [ISO 10589]. ISIS protocol is vulnerable to purge packet propagation. And it has no mechanism to trackback and locate the source when purge packet propagation does occure in the network. To address this problem, this document proposes to add a new TLV in purge packet to record the system ID of the router generating it. Wei, et al. Expires September 6, 2010 [Page 3] Internet-Draft New TLV for Purge Packet in ISIS March 2010 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 [RFC 2119]. Wei, et al. Expires September 6, 2010 [Page 4] Internet-Draft New TLV for Purge Packet in ISIS March 2010 3. Cases to generate purge packet The legitimate purge cases: (1)Originating IS purges its own LSP. (2)LSP owned by another IS ages out. (3)A new DIS is elected. The inappropriate purge cases: (1)An implementation misunderstanding [ISO 10589] generates purge packet when it receives corrupted LSP. (2)An implementation with bugs tries to self-purge and makes some truly egregious mistakes. (3)An implementation fails to retain the LSP header after purging while flooding is still in progress. Wei, et al. Expires September 6, 2010 [Page 5] Internet-Draft New TLV for Purge Packet in ISIS March 2010 4. Proposed New TLV in Purge Packet This document proposes a new TLV for purge packet, which records the system ID of the IS generating the purge packet. This kind of TLV SHOULD not be changed in purge packets sent by other routers than the initiator. The purpose to introduce this kind of TLV is to taceback and locate the source IS that initiates the purge packet when purge packet propagation occures in the network, which is usually caused by the inappropriate cases mentioned in above section of this document. This method is useful in both lab and field network. It is helpful for both developers and network operators. The new TLV is: CODE - XX (to be assigned) LENGTH - total length of the value field. VALUE - System ID of the Intermediate System that initiates the Purge packet Wei, et al. Expires September 6, 2010 [Page 6] Internet-Draft New TLV for Purge Packet in ISIS March 2010 5. Security Considerations The impact on [RFC5304] and [RFC5310] is for further study. Wei, et al. Expires September 6, 2010 [Page 7] Internet-Draft New TLV for Purge Packet in ISIS March 2010 6. IANA Considerations A new code is solicited to be assigned to the proposed TLV. Wei, et al. Expires September 6, 2010 [Page 8] Internet-Draft New TLV for Purge Packet in ISIS March 2010 7. Informative 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. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [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. Wei, et al. Expires September 6, 2010 [Page 9] Internet-Draft New TLV for Purge Packet in ISIS March 2010 Authors' Addresses Fang Wei China Mobile No. 29, Financial Street, Xicheng District Beijing 100032 China Email: weifang@chinamobile.com Yue Qin China Mobile No. 29, Financial Street, Xicheng District Beijing 100032 China Email: qinyue@chinamobile.com Lianyuan Li China Mobile Unit2, Dacheng Plaza, No. 28 Xuanwumenxi Ave, Xuanwu District Beijing 100053 China Email: lilianyuan@chinamobile.com Zhenqiang Li China Mobile Unit2, Dacheng Plaza, No. 28 Xuanwumenxi Ave, Xuanwu District Beijing 100053 China Email: lizhenqiang@chinamobile.com Wei, et al. Expires September 6, 2010 [Page 10]