Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures
RFC 4379

Network Working Group                                        K. Kompella
Request for Comments: 4379                        Juniper Networks, Inc.
Updates: 1122                                                 G. Swallow
Category: Standards Track                            Cisco Systems, Inc.
                                                           February 2006

   Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document describes a simple and efficient mechanism that can be
   used to detect data plane failures in Multi-Protocol Label Switching
   (MPLS) Label Switched Paths (LSPs).  There are two parts to this
   document: information carried in an MPLS "echo request" and "echo
   reply" for the purposes of fault detection and isolation, and
   mechanisms for reliably sending the echo reply.

Table of Contents

   1. Introduction ....................................................2
      1.1. Conventions ................................................3
      1.2. Structure of This Document .................................3
      1.3. Contributors ...............................................3
   2. Motivation ......................................................4
      2.1. Use of Address Range 127/8 .................................4
   3. Packet Format ...................................................6
      3.1. Return Codes ..............................................10
      3.2. Target FEC Stack ..........................................11
           3.2.1. LDP IPv4 Prefix ....................................12
           3.2.2. LDP IPv6 Prefix ....................................13
           3.2.3. RSVP IPv4 LSP ......................................13
           3.2.4. RSVP IPv6 LSP ......................................14
           3.2.5. VPN IPv4 Prefix ....................................14
           3.2.6. VPN IPv6 Prefix ....................................15
           3.2.7. L2 VPN Endpoint ....................................16

Kompella & Swallow          Standards Track                     [Page 1]
RFC 4379           Detecting MPLS Data Plane Failures      February 2006

           3.2.8. FEC 128 Pseudowire (Deprecated) ....................16
           3.2.9. FEC 128 Pseudowire (Current) .......................17
           3.2.10. FEC 129 Pseudowire ................................18
           3.2.11. BGP Labeled IPv4 Prefix ...........................19
           3.2.12. BGP Labeled IPv6 Prefix ...........................20
           3.2.13. Generic IPv4 Prefix ...............................20
           3.2.14. Generic IPv6 Prefix ...............................21
           3.2.15. Nil FEC ...........................................21
      3.3. Downstream Mapping ........................................22
           3.3.1. Multipath Information Encoding .....................26
           3.3.2. Downstream Router and Interface ....................28
      3.4. Pad TLV ...................................................29
      3.5. Vendor Enterprise Number ..................................29
      3.6. Interface and Label Stack .................................29
      3.7. Errored TLVs ..............................................31
      3.8. Reply TOS Byte TLV ........................................31
   4. Theory of Operation ............................................32
      4.1. Dealing with Equal-Cost Multi-Path (ECMP) .................32
      4.2. Testing LSPs That Are Used to Carry MPLS Payloads .........33
      4.3. Sending an MPLS Echo Request ..............................33
      4.4. Receiving an MPLS Echo Request ............................34
           4.4.1. FEC Validation .....................................40
      4.5. Sending an MPLS Echo Reply ................................41
      4.6. Receiving an MPLS Echo Reply ..............................42
      4.7. Issue with VPN IPv4 and IPv6 Prefixes .....................42
      4.8. Non-compliant Routers .....................................43
   5. References .....................................................43
      5.1. Normative References ......................................43
      5.2. Informative References ....................................44
   6. Security Considerations ........................................44
   7. IANA Considerations ............................................46