Flow-Aware Transport of Pseudowires over an MPLS Packet Switched Network
RFC 6391

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Internet Engineering Task Force (IETF)                    S. Bryant, Ed.
Request for Comments: 6391                                   C. Filsfils
Category: Standards Track                                  Cisco Systems
ISSN: 2070-1721                                                 U. Drafz
                                                        Deutsche Telekom
                                                             V. Kompella
                                                                J. Regan
                                                          Alcatel-Lucent
                                                               S. Amante
                                             Level 3 Communications, LLC
                                                           November 2011

Flow-Aware Transport of Pseudowires over an MPLS Packet Switched Network

Abstract

   Where the payload of a pseudowire comprises a number of distinct
   flows, it can be desirable to carry those flows over the Equal Cost
   Multiple Paths (ECMPs) that exist in the packet switched network.
   Most forwarding engines are able to generate a hash of the MPLS label
   stack and use this mechanism to balance MPLS flows over ECMPs.

   This document describes a method of identifying the flows, or flow
   groups, within pseudowires such that Label Switching Routers can
   balance flows at a finer granularity than individual pseudowires.
   The mechanism uses an additional label in the MPLS label stack.

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/rfc6391.

Bryant, et al.               Standards Track                    [Page 1]
RFC 6391                         FAT-PW                    November 2011

Copyright Notice

   Copyright (c) 2011 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
      1.1. Requirements Language ......................................4
      1.2. ECMP in Label Switching Routers ............................4
      1.3. Flow Label .................................................4
   2. Native Service Processing Function ..............................5
   3. Pseudowire Forwarder ............................................6
      3.1. Encapsulation ..............................................7
   4. Signalling the Presence of the Flow Label .......................8
      4.1. Structure of Flow Label Sub-TLV ............................9
   5. Static Pseudowires ..............................................9
   6. Multi-Segment Pseudowires .......................................9
   7. Operations, Administration, and Maintenance (OAM) ..............10
   8. Applicability of PWs Using Flow Labels .........................11
      8.1. Equal Cost Multiple Paths .................................12
      8.2. Link Aggregation Groups ...................................13
      8.3. Multiple RSVP-TE Paths ....................................13
      8.4. The Single Large Flow Case ................................14
      8.5. Applicability to MPLS-TP ..................................15
      8.6. Asymmetric Operation ......................................15
   9. Applicability to MPLS LSPs .....................................15
   10. Security Considerations .......................................16
   11. IANA Considerations ...........................................16
   12. Congestion Considerations .....................................16
   13. Acknowledgements ..............................................17
   14. References ....................................................17
      14.1. Normative References .....................................17
      14.2. Informative References ...................................18

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