Assigned BGP extended communities
Network Working Group B. Decraene
Intended status: Standards Track P. Francois
Expires: July 17, 2015 IMDEA Networks
January 13, 2015
Assigned BGP extended communities
This document defines an IANA registry in order to assign non-
transitive extended communities from. These are similar to the
existing well-known BGP communities defined in RFC 1997 but provide a
control over inter-AS community advertisement as, per RFC RFC 4360,
they are not transitive across Autonomous System boundaries.
For that purpose, this document defines the use of the reserved
Autonomous System number 0.65535 in the non-transitive generic four-
octet AS specific extended community type.
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.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 17, 2015.
Decraene & Francois Expires July 17, 2015 [Page 1]
Internet-Draft Assigned extended communities January 2015
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
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.
[RFC1997] defines the BGP community attribute and some BGP well-known
communities whose meaning SHALL be understood by all compliant
implementations. New communities can be registered in the IANA "BGP
Well-known Communities" registry but it can't be assumed anymore that
they will be known by all BGP implementations. Implementations or
BGP policies which recognize them will behave as specified in the
IANA registry. Implementations which do not recognize those new IANA
assigned communities will propagate them from BGP neighbor to BGP
neighbor and from AS to AS with an unlimited scope.
There is currently no agreed way to register a non-transitive well-
On one hand, [RFC1997] defines BGP Well-known communities with no
structure to set their transitiveness across ASes. Without
structure, communities can only be filtered by explicitly enumerating
all community values that will be denied or allowed to BGP speakers
in neighboring ASes. This is not satisfactory as this would require
upgrading all border routers to understand this community before its
On the other hand, [RFC4360] defines the BGP extended community
attribute with a structure including a type and a transitive bit "T".
This transitive bit, when set, allows to restrict the scope of the
community within an AS. But there is no IANA registry to allocate
one well-known extended community. [RFC4360] defines IANA registries
to allocate BGP Extended Communities types. Each type is able to
encode 2^48 or 2^56 values depending on the type being extended or
regular. Therefore, one needing to reserve a single non-transitive
extended community would need to reserve an extended subtype which
represents 2^48 communities, while a single value is used. This
Decraene & Francois Expires July 17, 2015 [Page 2]
Show full document text