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
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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
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