Network Working Group Sami Boutros (Ed.) Internet Draft Siva Sivabalan (Ed.) Intended status: Standards Track George Swallow Expires: September 2010 Cisco Systems, Inc. March 1, 2010 Definition of Time-to-Live TLV for LSP-Ping Mechanisms draft-boutros-mpls-lsp-ping-ttl-tlv-00.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/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 1, 2010. Abstract LSP-Ping is a widely deployed Operation, Administration, and Maintenance (OAM) mechanism in MPLS networks. However, in the present form, this mechanism is inadequate to verify connectivity of a segment of a Multi-Segment PseudoWire (MS-PW) from any node on the path of the MS-PW. This document defines a TLV to address this shortcomming. Boutros Expires January 6, 2011 [Page 1] Internet-Draftdraft-boutros-mpls-lsp-ping-ttl-tlv-00.txt March 2010 Table of Contents 1. Introduction...................................................2 2. Terminology....................................................3 3. Time To Live TLV...............................................3 4. Operation......................................................3 5. Security Considerations........................................4 6. IANA Considerations............................................4 7. References.....................................................4 7.1. Normative References......................................4 7.2. Informative References....................................5 Author's Addresses................................................5 Full Copyright Statement..........................................5 Intellectual Property Statement...................................6 1. Introduction A MS-PW [4] can span across multiple service provider networks. In order to allow Service Providers (SP) to verify segments of such MS- PW from any node on the path of the MS-PW, any node along the path of the MS-PW, should be able to originate an LSP-Ping [2][3] echo request packet to any another node along the path of the MS-PW and receive the corresponding echo reply. If the originator of the echo request is at the end of a MS-PW, the receiver of the request can send the reply back to the sender without knowing the hop-count distance of the originator. For example, the reply will be intercepted by the originator regardless of the TTL value on the reply packet. But, if the originator is not at the end of the MS-PW, the receiver of the echo request MAY need to know how many hops away the originator of the echo request is so that it can set the TTL value on the MPLS header for the echo reply to be intercepted at the originator node. A new optional TTL TLV is being proposed in this document this TLV will be added by the originator of the echo request to inform the receiver how many hops away the originator is on the path of the MS- PW. Conventions used in this document 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 [1]. Boutros Expires September 1, 2010 [Page 2] Internet-Draftdraft-boutros-mpls-lsp-ping-ttl-tlv-00.txt March 2010 2. Terminology LSR: Label Switching Router MPLS-OAM: MPLS Operations, Administration and Maintenance MS-PW: Multi-Segment PseudoWire PW: PseudoWire TLV: Type Length Value TTL: Time To Live 3. Time To Live TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | type = TBD | Length = 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | value | +-+-+-+-+-+-+-+-+ Figure 1: Time To Live TLV format The TTL TLV has the format shown in Figure 1. This TLV shall be included in the echo request by the originator of request. If a TTL TLV is present in the echo request, the LSR processing the echo request MUST use the TTL value specified in TLV in the MPLS header of the echo reply. The use of this TLV is optional. If the value field is zero, the LSP Ping Echo request packet will be dropped. If a receiver does not understand the TTL TLV, it can simply ignore the TLV. In the absence of TTL TLV or if TTL TLV is ignored by a receiver, the determination of the TTL value used in the MPLS label on the echo reply is beyond the scope of this document. 4. Operation In this section, we explain a use case for the TTL TLV with an MPLS MS-PW. Boutros Expires September 1, 2010 [Page 3] Internet-Draftdraft-boutros-mpls-lsp-ping-ttl-tlv-00.txt March 2010 <------------------MS-PW ---------------------> A B C D E o -------- o -------- o --------- o --------- o ------Echo Request-----> <-----Echo Reply-------- Figure 2: Use-case with MS-PWs Let us assume a MS-PW going through LSRs A, B, C, D, and E. Furthermore, assume that an operator wants to perform a connectivity check between B and D from B. Thus, an LSP-Ping request with the TTL TLV is originated from B and sent towards D. The echo request packet contains the FEC of the PW Segment between C and D. The value field of the TTL TLV and the TTL field of the MPLS label are set to 2. The echo request is intercepted at D because of TTL expiry. D detects the TTL TLV in the request, and use the TTL value (i.e., 2) specified in the TLV on the MPLS label of the echo reply. The echo reply will be intercepted by B because of TTL expiry. 5. Security Considerations TBD 6. IANA Considerations IANA maintains the registry for the Type field of top-level TLVs as well as any associated sub-TLVs. IANA is requested to assign a new Type value for the TTL TLV defined in this document. The suggested value is 11. 7. References 7.1. Normative References [1] Bradner. S, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March, 1997. [2] K. Kompella, G. Swallow, "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures", RFC 4379, February 2006. Boutros Expires September 1, 2010 [Page 4] Internet-Draftdraft-boutros-mpls-lsp-ping-ttl-tlv-00.txt March 2010 [3] T. Nadeau, et. al, "Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for Pseudowires ", RFC 5085, December 2007. 7.2. Informative References [4] Nabil Bitar, et. al, "Requirements for Multi-Segment Pseudowire Emulation Edge-to-Edge (PWE3)", RFC5254, October 2008. Author's Addresses Sami Boutros Cisco Systems, Inc. 3750 Cisco Way San Jose, California 95134 USA Email: sboutros@cisco.com Siva Sivabalan Cisco Systems, Inc. 2000 Innovation Drive Kanata, Ontario, K2K 3E8 Canada Email: msiva@cisco.com George Swallow Cisco Systems, Inc. 300 Beaver Brook Road Boxborough , MASSACHUSETTS 01719 United States Email: swallow@cisco.com Full Copyright Statement 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 Boutros Expires September 1, 2010 [Page 5] Internet-Draftdraft-boutros-mpls-lsp-ping-ttl-tlv-00.txt March 2010 (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. 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