Return Path Specified Label Switched Path (LSP) Ping
RFC 7110

Internet Engineering Task Force (IETF)                           M. Chen
Request for Comments: 7110                                        W. Cao
Category: Standards Track                   Huawei Technologies Co., Ltd
ISSN: 2070-1721                                                  S. Ning
                                                     Tata Communications
                                                               F. Jounay
                                                               Orange CH
                                                               S. Delord
                                                            January 2014

          Return Path Specified Label Switched Path (LSP) Ping

Abstract

   This document defines extensions to the data-plane failure-detection
   protocol for Multiprotocol Label Switching (MPLS) Label Switched
   Paths (LSPs) known as "LSP ping".  These extensions allow a selection
   of the LSP to be used for the echo reply return path.  Enforcing a
   specific return path can be used to verify bidirectional connectivity
   and also increase LSP ping robustness.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7110.

Chen, et al.                 Standards Track                    [Page 1]
RFC 7110             Return Path Specified LSP Ping         January 2014

Copyright Notice

   Copyright (c) 2014 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 ....................................................3
   2. Requirements Language ...........................................3
   3. Problem Statements and Solution Overview ........................3
      3.1. Limitations of Existing Mechanisms for Bidirectional LSPs ..4
      3.2. Limitations of Existing Mechanisms for Handling
           Unreliable Return Paths ....................................4
   4. Extensions ......................................................5
      4.1. Reply via Specified Path Mode ..............................6
      4.2. Reply Path (RP) TLV ........................................6
      4.3. Tunnel Sub-TLVs ............................................8
           4.3.1. IPv4 RSVP Tunnel Sub-TLV ...........................10
           4.3.2. IPv6 RSVP Tunnel Sub-TLV ...........................11
           4.3.3. Static Tunnel Sub-TLV ..............................12
      4.4. Reply TC TLV ..............................................12
   5. Theory of Operation ............................................13
      5.1. Sending an Echo Request ...................................14
      5.2. Receiving an Echo Request .................................14
      5.3. Sending an Echo Reply .....................................15
      5.4. Receiving an Echo Reply ...................................16
      5.5. Non-IP Encapsulation for MPLS-TP LSPs .....................16
   6. Security Considerations ........................................16
   7. IANA Considerations ............................................17
      7.1. TLVs ......................................................17
      7.2. New Target FEC Stack Sub-TLVs .............................17
      7.3. New Reply Mode ............................................17
      7.4. Reply Path Return Code ....................................18
   8. Contributors ...................................................19
   9. Acknowledgements ...............................................19
   10. References ....................................................19
      10.1. Normative References .....................................19
      10.2. Informative References ...................................20

Chen, et al.                 Standards Track                    [Page 2]