Extended Administrative Groups in MPLS-TE
draft-osborne-mpls-extended-admin-groups-00

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Document Type Active Internet-Draft (individual)
Author Eric Osborne 
Last updated 2013-02-13
Replaced by RFC 7308, RFC 7308
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Network Working Group                                         E. Osborne
Internet-Draft                                                     Cisco
Intended status: Experimental                          February 13, 2013
Expires: August 17, 2013

               Extended Administrative Groups in MPLS-TE
              draft-osborne-mpls-extended-admin-groups-00

Abstract

   This document provides additional administrative groups (sometimes
   referred to as "link colors") to the IGP extensions for MPLS-TE.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on August 17, 2013.

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   document authors.  All rights reserved.

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   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
   2.  Extended Administrative Groups sub-TLV  . . . . . . . . . . . . 3
     2.1.  Packet Format . . . . . . . . . . . . . . . . . . . . . . . 3
     2.2.  Admin group numbering . . . . . . . . . . . . . . . . . . . 4
     2.3.  Backward compatability  . . . . . . . . . . . . . . . . . . 4
       2.3.1.  AG and EAG coexistence  . . . . . . . . . . . . . . . . 4
       2.3.2.  Desire for unadvertised EAG bits  . . . . . . . . . . . 4
   3.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   6.  Normative References  . . . . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 5

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1.  Introduction

   MPLS-TE advertises 32 administrative groups (commonly referred to as
   "colors" or "link colors") using the Administrative Group sub-TLV of
   the Link TLV.  This is defined for OSPF [RFC3630]and ISIS [RFC5305].

   This document adds a sub-TLV to the IGP TE extensions, "Extended
   Administrative Group".  It

2.  Extended Administrative Groups sub-TLV

   The Extended Administrative Groups sub-TLV is used in addition to the
   Administrative Groups when a device wishes to advertise more than 32
   colors for a link.  The EAG sub-TLV is optional.

   This document uses the term 'colors' as a shorthand to refer to
   particular bits with an AG or EAG.  The examples in this document use
   'red' to represent the least significant bit in the AG (red == 0x1),
   'blue' to represent the second bit (blue == 0x2).  To say that a link
   has a given color or that the specified color is set on the link is
   to say that the corresponding bit or bits in the link's AG are set to
   1.

2.1.  Packet Format

   The format of the Extended Administrative Groups sub-TLV is:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Type: Extended Admin Group    |  Length: Variable             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Value: Extended Admin Group Value                             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        ...........                            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Value: Extend Admin Group Value                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Length is the size of the Extended Admin Group (EAG) value in
   octets.  The EAG may be of any length, but must be a multiple of 4
   octets.

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2.2.  Admin group numbering

   By convention, the existing Administrative Group TLVs are numbered 0
   (LSB) to 31 (MSB).  The EAG values pick up where this numbering
   scheme leaves off.  The LSB in the EAG is 32.  If the EAG is 4 bytes
   in length, the MSB is 63.  If the EAG is 8 bytes in length, the MSB
   is 95.

2.3.  Backward compatability

   There are two things to consider for backward compatibility with
   existing AG implementations - how do AG and EAG coexist, and what
   happens if a node has matching criteria for unadvertised EAG bits?

2.3.1.  AG and EAG coexistence

   If a node advertises the EAG sub-TLV it MUST also advertise the
   existing Administrative Group (AG) sub-TLV defined in RFCs 3630 and
   5305.  This ensures that the first bit of the EAG sub-TLV is always
   bit 32, and ensures maximum interoperability with legacy
   implementations.

2.3.2.  Desire for unadvertised EAG bits

   The existing AG bits are optional; thus a node may be configured with
   a preference to include red or exclude blue, and be faced with a link
   that is not advertising a value for either blue or red.  What does an
   implementation do in this case?  It shouldn't assume that red is set,
   but it is also arguably incorrect to assume that red is NOT set, as a
   bit must first exist before it can be set to 0.

   Practically speaking this has not been an issue for deployments, as
   many implementations always advertise the AG bits, often with a
   default value of 0x00000000.  However, this issue may be of more
   concern once EAGs are added to the network.  EAGs may exist on some
   nodes but not others, and the EAG length may be longer for some links
   than for others.

   Each implementation is free to choose its own method for handling
   this question.  However, to encourage maximum interoperability an
   implementation SHOULD treat specified but unadvertised EAG bits as if
   they are set to 0.  A node MAY provide other (configurable)
   strategies for handling this case.

3.  Security Considerations

   This extension adds no new security considerations.

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4.  IANA Considerations

   This document requests a sub-TLV allocation in both OSPF and ISIS.

5.  Acknowledgements

   Thanks to Santiago Alvarez and Rohit Gupta for their review and
   comments.

6.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3630]  Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
              (TE) Extensions to OSPF Version 2", RFC 3630,
              September 2003.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, October 2008.

Author's Address

   Eric Osborne
   Cisco

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