Deprecation of BGP Entropy Label Capability Attribute
RFC 7447

Document Type RFC - Proposed Standard (February 2015; No errata)
Updates RFC 6790
Last updated 2015-10-14
Replaces draft-scudder-mpls-deprecate-bgp-entropy-label
Stream IETF
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Document shepherd Loa Andersson
Shepherd write-up Show (last changed 2014-10-22)
IESG IESG state RFC 7447 (Proposed Standard)
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Responsible AD Spencer Dawkins
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IANA IANA review state Version Changed - Review Needed
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Internet Engineering Task Force (IETF)                        J. Scudder
Request for Comments: 7447                                   K. Kompella
Updates: 6790                                           Juniper Networks
Category: Standards Track                                  February 2015
ISSN: 2070-1721

         Deprecation of BGP Entropy Label Capability Attribute

Abstract

   The BGP Entropy Label Capability attribute is defined in RFC 6790.
   Regrettably, it has a bug: although RFC 6790 mandates that routers
   incapable of processing Entropy Labels must remove the attribute,
   fulfillment of this requirement cannot be guaranteed in practice.
   This specification deprecates the attribute.  A forthcoming document
   will propose a replacement.

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/rfc7447.

Copyright Notice

   Copyright (c) 2015 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Scudder & Kompella           Standards Track                    [Page 1]
RFC 7447                   Deprecation of ELCA             February 2015

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Deprecation of ELCA . . . . . . . . . . . . . . . . . . . . .   2
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   3
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   3
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   [RFC6790] defines the Entropy Label Capability attribute (ELCA), an
   optional, transitive BGP path attribute.  For correct operation, an
   intermediate node modifying the next hop of a route must remove the
   ELCA unless the node doing so is able to process entropy labels.
   Sadly, this requirement cannot be fulfilled with the ELCA as
   specified, because it is an optional, transitive attribute.  By
   definition, a node that does not support the ELCA will propagate the
   attribute (this is a general property of optional, transitive
   attributes; see [RFC4271]).  But such an ELCA-oblivious node is
   likely to be incapable of processing entropy labels and is exactly
   the node that we desire to remove the attribute!

   This specification updates RFC 6790 by deprecating the version of
   ELCA defined in Section 5.2 of that document.  A forthcoming document
   will propose a replacement.  All other sections of RFC 6790 are
   unchanged.

1.1.  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].

2.  Deprecation of ELCA

   This document deprecates the ELCA path attribute.  This means that
   implementations MUST NOT generate the attribute.  If received, the
   attribute MUST be treated as any other unrecognized optional,
   transitive attribute as per [RFC4271], until and unless the code
   point is reused by some new specification.  (To the authors' best
   knowledge, there are no implementations of ELCA at the time of
   writing.)

Scudder & Kompella           Standards Track                    [Page 2]
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