Definition of Time to Live TLV for LSP-Ping Mechanisms
RFC 7394

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Internet Engineering Task Force (IETF)                        S. Boutros
Request for Comments: 7394                                  S. Sivabalan
Category: Standards Track                                     G. Swallow
ISSN: 2070-1721                                                S. Saxena
                                                           Cisco Systems
                                                               V. Manral
                                                          Ionos Networks
                                                               S. Aldrin
                                               Huawei Technologies, Inc.
                                                           November 2014

         Definition of Time to Live TLV for LSP-Ping Mechanisms

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) and/or bidirectional
   co-routed Label Switched Path (LSP) from any node on the path of the
   MS-PW and/or bidirectional co-routed LSP.  This document defines a
   TLV to address this shortcoming.

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/rfc7394.

Boutros, et al.              Standards Track                    [Page 1]
RFC 7394             TTL TLV for LSP-Ping Mechanisms       November 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 ....................................................2
   2. Terminology .....................................................3
   3. Time To Live TLV ................................................4
      3.1. TTL TLV Format .............................................4
      3.2. Usage ......................................................4
   4. Operation .......................................................5
      4.1. Traceroute Mode ............................................6
      4.2. Error Scenario .............................................6
   5. Security Considerations .........................................6
   6. IANA Considerations .............................................7
   7. References ......................................................7
      7.1. Normative References .......................................7
   Acknowledgements ...................................................7
   Contributors .......................................................7
   Authors' Addresses .................................................8

1.  Introduction

   An MS-PW may span across multiple service provider networks.  In
   order to allow Service Providers (SPs) to verify segments of such
   MS-PWs 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 MPLS Echo Request
   packet to any other node along the path of the MS-PW and receive the
   corresponding MPLS Echo Reply.  If the originator of the MPLS 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.  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
   MPLS Echo Request may need to know how many hops away the originator

Boutros, et al.              Standards Track                    [Page 2]
RFC 7394             TTL TLV for LSP-Ping Mechanisms       November 2014

   of the MPLS Echo Request is so that it can set the TTL value on the
   MPLS header for the MPLS Echo Reply to be intercepted at the
   originator node.

   In MPLS networks, for bidirectional co-routed LSPs, if it is desired