Network Working Group Enke Chen Internet Draft Albert Tian Intended status: Standards Track Cisco Systems Expiration Date: September 10, 2009 March 9, 2009 TTL-Based Security Option for the LDP Hello Message draft-chen-ldp-ttl-02.txt 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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on September 10, 2009. Copyright Notice Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract To facilitate the deployment of the TTL-based security mechanism for Chen & Tian [Page 1] Internet Draft draft-chen-ldp-ttl-02.txt March 2009 LDP, in this document we propose a new optional parameter for the LDP Hello Message that can be used by a LSR to indicate its support of the TTL-based mechanism. 1. Introduction The LDP [LDP] sessions established following the LDP basic discovery are between two directly connected LSRs. As a result, the TTL-based security mechanism described in [RFC3682] is fully applicable to such sessions. To deploy the TTL-based security mechanism, however, both LSRs involved in the LDP session must be coordinated and synchronized in setting and checking the TTL values. The coordination effort may not be trivial for a large network. To facilitate the deployment of the TTL-based security mechanism for LDP, in this document we propose a new optional parameter for the LDP Hello Message that can be used by a LSR to indicate its support of the TTL-based mechanism. 2. Specification of Requirements 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. Protocol Extension The new optional parameter for the LDP Hello Message is defined as the following: Optional Parameter: Support for TTL-based Security Type: See the IANA Considerations section Length: 0 U bit: 1 F bit: 0 This optional parameter MAY be used by a LSR to indicate its support for the TTL-based security mechanism [RFC3682]. When both LSRs exchanging the LDP Hello Messages support the TTL-based security mechanism, the LSRs MUST follow the TTL-based security procedures for the LDP peer to be established between them. More specifically, o The TTL field of an outbound packet for the LDP session MUST be set to the maximum value (255). Chen & Tian [Page 2] Internet Draft draft-chen-ldp-ttl-01.txt March 2009 o For an inbound packet to be accepted, the TTL field of the packet MUST be 255 if the TTL value is not decremented by the receiving LSR. Otherwise, the TTL field MUST be 254. The choice between these two values is implementation specific, and is a local matter. The optional parameter SHOULD NOT be included in a LDP targeted Hello Message sent by a LSR, and SHOULD be ignored in a targeted Hello Message received by a LSR. 4. IANA Considerations This document defines a new optional parameter for the LDP Hello Message. The type code needs to be assigned by IANA. 5. Security Considerations This extension to LDP does not change the underlying security properties with The Generalized TTL Security Mechanism (GTSM) [RFC5082]. This extension is only application to LDP peers as a result of the LDP basic discovery. For LDP sessions resulting from the LDP targeted discovery, the TCP MD5 is recommended by [LDP]. 6. Acknowledgments The authors would like to thank Rajiv Asati and Carlos Pignataro for their suggestions and discussions. 7. References 7.1. Normative References [LDP] L. Andersson, P. Doolan, N. Feldman, A. Fredette, and B. Thomas, "LDP Specification", RFC 3036, January 2001. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2. Non-normative References [RFC5082] V. Gill, J. Heasley, D. Meyer, P. Savola, C. Pignataro, "The Generalized TTL Security Mechanism (GTSM)", RFC 5082, Oct 2007. Chen & Tian [Page 3] Internet Draft draft-chen-ldp-ttl-02.txt March 2009 8. Authors' Addresses Enke Chen Cisco Systems, Inc. 170 W. Tasman Dr. San Jose, CA 95134 Email: enkechen@cisco.com Albert Tian Cisco Systems, Inc. 3700 Cisco Way, San Jose, CA 95134 Email: altian@cisco.com Chen & Tian [Page 4]