Network Working Group Albert J. Tian Internet Draft Expiration Date: Aug 2006 Redback Networks Feb 2006 Generation ID for LDP draft-tian-ldp-gen-id-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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. Abstract This document proposed two optional Generation ID TLVs in LDP Hello messages and in LDP Initialization messages to speed up LDP convergence in certain scenarios. Tian [Page 1] Internet Draft draft-tian-ldp-gen-id-00.txt Feb 2006 1. Introduction Consider two LSRs, LSRa and LSRb, that have an LDP session established between them. LSRa is playing an active role in the LDP session establishment, while LSRb is playing a passive role. For certain LDP implementations, it is possible for the passive LSR LSRb to fail and recover before the Hello Hold Time expires on its LDP neighbor LSRa. It is also possible for LSRb to fail in a way that it could not properly shutdown the TCP connections. In this scenario, the only way for the active LDP neighbor LSRa to detect the failure of LSRb would be for the KeepAlive Time to expire on LSRa. In normal LDP configurations, the KeepAlive Time is usually configured on the order of minutes. Before the KeepAlive Time expires, proper LDP convergence can not be initiated. 2. LDP Extension To solve this problem, we propose two new optional TLVs, Hello Generation ID TLV in LDP Hello messages, and Session Generation Generation ID TLV in Initialization Messages. Both two TLVs have the same format but with different types: Optional Parameter Type Length Value Hello Generation ID TBD 4 See below Session Generation ID TBD 4 See below Hello Generation ID TLV and Session Generation ID TLV specify a 4 octet unsigned generation ID that identifies an LDP instance. 3. Operation 3.1. Sending Generation ID For each LSR, when its LDP instance is initialized, a 4 octet Generation ID should be generated. The Generation ID should remain the same for the life time of the LDP instance. Whenever the LSR needs to send out LDP Hello messages, it should include the Generation ID value in the Hello Generation TLV in the Hello messages; whenever the LSR needs to send out LDP Initialization messages, it should include the Generation ID value in the Session Generation TLV in the Initialization messages. Tian [Page 2] Internet Draft draft-tian-ldp-gen-id-00.txt Feb 2006 3.2. Receiving Generation ID Whenever an LSR receives LDP Initialization message from another LSR with optional Session Generation ID TLV, it may remember the Generation ID for the neighbor. Whenever an LSR receives an LDP Hello message from an LDP neighbor with a Hello Generation ID that is different from the remembered Session Generation ID received from the same neighbor, then the LSR may choose to terminate the LDP session to that neighbor. A Notification message may be generated before the termination of the session with error code TBD that indicates a Generation ID mismatch. 4. Security Considerations This document does not introduce any new security issues. 5. IANA Considerations This document proposes two new optional TLVs in LDP Hello messages and LDP Initialization messages. The types of the two TLVs need to be assigned by IANA. The document also proposes a new LDP Notification error code for Generation ID mismatch. The new error code also needs to be assigned by IANA. 6. Acknowledgments The author would like to thank Venkatesan Pradeep for his help. 7. References [RFC3036] L. Andersson, P. Doolan, N. Feldman, A. Fredette, and B. Thomas, "LDP Specification", RFC 3036, January 2001. Tian [Page 3] Internet Draft draft-tian-ldp-gen-id-00.txt Feb 2006 8. Author Information Albert J. Tian Redback Networks, Inc. 350 Holger Way San Jose, CA 95134 Email: tian@redback.com Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Tian [Page 4]