Extended Administrative Groups in MPLS Traffic Engineering (MPLS-TE)
RFC 7308

Document Type RFC - Proposed Standard (July 2014; No errata)
Last updated 2015-10-14
Replaces draft-osborne-mpls-extended-admin-groups
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Internet Engineering Task Force (IETF)                        E. Osborne
Request for Comments: 7308                                     July 2014
Category: Standards Track
ISSN: 2070-1721

  Extended Administrative Groups in MPLS Traffic Engineering (MPLS-TE)

Abstract

   MPLS Traffic Engineering (MPLS-TE) advertises 32 administrative
   groups (commonly referred to as "colors" or "link colors") using the
   Administrative Group sub-TLV.  This is defined for OSPFv2 (RFC 3630),
   OSPFv3 (RFC 5329) and IS-IS (RFC 5305).

   This document adds a sub-TLV to the IGP TE extensions, "Extended
   Administrative Group".  This sub-TLV provides for additional
   administrative groups (link colors) beyond the current limit of 32.

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/rfc7308.

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.

Osborne                      Standards Track                    [Page 1]
RFC 7308                  Extended Admin Groups                July 2014

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Extended Administrative Groups Sub-TLV  . . . . . . . . . . .   3
     2.1.  Packet Format . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Admin Group Numbering . . . . . . . . . . . . . . . . . .   4
     2.3.  Backward Compatibility  . . . . . . . . . . . . . . . . .   4
       2.3.1.  AG and EAG Coexistence  . . . . . . . . . . . . . . .   4
       2.3.2.  Desire for Unadvertised EAG Bits  . . . . . . . . . .   5
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Do we need more than 32 bits?

   The IGP extensions to support MPLS-TE (RFCs 3630 [RFC3630] and 5305
   [RFC5305]) define a link TLV known as Administrative Group (AG) with
   a limit of 32 AGs per link.  The concept of Administrative Groups
   comes from Section 6.2 of RFC 2702 [RFC2702], which calls them
   Resource Classes.  RFCs 3630 [RFC3630] and 5305 [RFC5305] describe
   the mechanics of the TLV and use the term Administrative Groups
   (sometimes abbreviated herein as AGs), as does this document.

   Networks have grown over time, and MPLS-TE has grown right along with
   them.  Administrative Groups are advertised as fixed-length 32-bit
   bitmasks.  This can be quite constraining, as it is possible to run
   out of values rather quickly.  One such use case is #5 in Section 6.2
   of RFC 2702 [RFC2702], using AGs to constrain traffic within specific
   topological regions of the network.  A large network may well have
   far more than 32 geographic regions.  One particular operator builds
   their network along the lines of this use case, using AGs to flag
   network regions down to the metro scale, e.g., Seattle, San
   Francisco, Dallas, Chicago, St. Louis, etc.  MPLS-TE tunnels are then
   specified with affinities to include or exclude specific metro
   regions in their path calculation.  Each metro region is given its
   own bit in the AG bitmask.  This means that 32 bits can only
   (cleanly) represent 32 metro areas.  It should be obvious that 32 may
   not be enough even for a US-based network, never mind a worldwide
   network.
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