draft-ietf-idr-reserved-extended-communities-02.txt   draft-ietf-idr-reserved-extended-communities-03.txt 
Network Working Group B. Decraene Network Working Group B. Decraene
Internet-Draft France Telecom - Orange Internet-Draft France Telecom - Orange
Intended status: Standards Track P. Francois Intended status: Standards Track P. Francois
Expires: June 7, 2012 IMDEA Networks Expires: November 22, 2012 IMDEA Networks
Dec 05, 2011 May 21, 2012
Assigned BGP extended communities Assigned BGP extended communities
draft-ietf-idr-reserved-extended-communities-02 draft-ietf-idr-reserved-extended-communities-03
Abstract Abstract
This document defines two IANA registries in order to assign This document defines an IANA registry in order to assign non-
transitive and non-transitive extended communities from. These are transitive extended communities from. These are similar to the
similar to the existing well-known BGP communities defined in RFC existing well-known BGP communities defined in RFC 1997 but provide a
1997 but provide an easier control of inter-AS community control over inter-AS community advertisement as, per RFC RFC 4360,
advertisement as a community could be chosen as transitive or non- they are not transitive across Autonomous System boundaries.
transitive across ASes.
For that purpose, this document defines the use of the reserved AS For that purpose, this document defines the use of the reserved
number 0 for the transitive and non-transitive generic four-octet AS Autonomous System number 0.65535 in the non-transitive generic four-
specific extended community types. octet AS specific extended community type.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 1, line 46 skipping to change at page 1, line 45
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 7, 2012. This Internet-Draft will expire on November 22, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
1. Introduction 1. Introduction
[RFC1997] defines the BGP community attribute and some BGP well-known [RFC1997] defines the BGP community attribute and some BGP well-known
communities whose meaning SHALL be understood by all compliant communities whose meaning SHALL be understood by all compliant
implementations. New communities can be registered in the IANA "BGP implementations. New communities can be registered in the IANA "BGP
Well-known Communities" registry but it can't be assumed anymore that Well-known Communities" registry but it can't be assumed anymore that
they will be known by all BGP implementations. Implementations or they will be known by all BGP implementations. Implementations or
BGP policies which recognize them will behave as specified. BGP policies which recognize them will behave as specified in the
Implementations which do not recognize those new reserved communities IANA registry. Implementations which do not recognize those new IANA
will propagate them from BGP neighbor to BGP neighbor and from AS to assigned communities will propagate them from BGP neighbor to BGP
AS with an unlimited scope. neighbor and from AS to AS with an unlimited scope.
There is currently no agreed way to register a non transitive well- There is currently no agreed way to register a non-transitive well-
known community: known community.
On one hand, [RFC1997] defines BGP Well-known communities with no On one hand, [RFC1997] defines BGP Well-known communities with no
structure to set their transitiveness across ASes. Without structure to set their transitiveness across ASes. Without
structure, communities can only be filtered by explicitly enumerating structure, communities can only be filtered by explicitly enumerating
all community values that will be denied or allowed to BGP speakers all community values that will be denied or allowed to BGP speakers
in neighboring ASes. This is not satisfactory as this would require in neighboring ASes. This is not satisfactory as this would require
upgrading all border routers to understand this community before its upgrading all border routers to understand this community before its
first usage. first usage.
On the other hand, [RFC4360] defines the BGP extended community On the other hand, [RFC4360] defines the BGP extended community
attribute with a structure including a type and a transitive bit "T". attribute with a structure including a type and a transitive bit "T".
This transitive bit, when set, allows to restrict the scope of the This transitive bit, when set, allows to restrict the scope of the
community within an AS. But their is no IANA registry to allocate community within an AS. But there is no IANA registry to allocate
one well-known extended community. [RFC4360] defines IANA registries one well-known extended community. [RFC4360] defines IANA registries
to allocate BGP Extended Communities types. Each type is able to 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 encode 2^48 or 2^56 values depending on the type being extended or
regular. Therefore, one needing to reserve a single non-transitive regular. Therefore, one needing to reserve a single non-transitive
extended community would need to reserve an extended subtype which extended community would need to reserve an extended subtype which
represents 2^48 communities, while a single value is used. This represents 2^48 communities, while a single value is used. This
would both waste the resources and disable the ability to define would both waste the resources and disable the ability to define
global policies on reserved communities, such as to accept them or to global policies on reserved communities, such as to accept them or to
filter them out. filter them out. In addition, using a new community type typically
requires a software upgrade on both the router setting the community
and the router using it in a BGP policy. So this would not allow the
networking community to quickly define and use a new community.
To address this limitation, this document defines two IANA registries To address this limitation, this document defines an IANA registry in
in order to allow the registration of transitive and non-transitive order to allow the registration of non-transitive extended
extended communities. These are similar to the existing Well-known communities. These are similar to the existing Well-known BGP
BGP communities defined in [RFC1997] but provides a control on communities defined in [RFC1997] but provides a control on inter-AS
inter-AS community advertisement as a community could be chosen as community advertisement. Indeed, as per [RFC4360] non-transitive
transitive or non-transitive across ASes. communities are removed from routes propagated to another AS.
2. Assigned extended communities 2. Assigned non-transitive extended communities
[I-D.ietf-idr-as4octet-extcomm-generic-subtype] defines a generic [I-D.ietf-idr-as4octet-extcomm-generic-subtype] defines a generic
sub-type for the four-octet AS specific extended community. The sub-type for the four-octet AS specific extended community. The
value of the four-octets Global Administrator sub-field contains a value of the four-octets Global Administrator sub-field contains a
four-octet Autonomous System number. The value of their two-octet four-octet Autonomous System number. The value of their two-octet
Local Administrator sub-field has semantics defined by the Autonomous Local Administrator sub-field has semantics defined by the Autonomous
System set in the Global Administrator sub-field. System set in the Global Administrator sub-field.
This document updates [I-D.ietf-idr-as4octet-extcomm-generic-subtype] This document updates [I-D.ietf-idr-as4octet-extcomm-generic-subtype]
and defines the use of the Local Administrator sub-field when the AS and defines the use of the Local Administrator sub-field of the "non-
number encoded in the Global Administrator sub-field has the reserved transitive generic four-octet AS specific" extended community type
value 0. when the AS number has the reserved value 0.65535 (0x0000FFFF).
When the AS number encoded in the Global Administrator sub-field has When the AS number, encoded in the Global Administrator sub-field,
the reserved value 0, the communities have global significance. The has the reserved value 0.65535, the communities have global
lists of those communities are maintained by the IANA in the significance. The lists of those communities are maintained by the
registries "Assigned transitive extended communities" for the IANA in the registry "Assigned non-transitive extended communities".
"transitive generic four-octet AS specific" extended community type
and "Assigned non-transitive extended communities" for the "non-
transitive generic four-octet AS specific" extended community type.
Note that this use of the reserved AS number 0 in the AS field of the Note that this use of the reserved AS number 0.65535 in the AS field
communities is similar to the one defined by [RFC1997] for the BGP of the communities is similar to the one defined by [RFC1997] for the
Well-Known communities. BGP Well-Known communities. In particular, [RFC1997] also uses the
reserved AS number 65535.
3. IANA Considerations 3. Assigned transitive extended communities
The IANA is requested to create and maintain a registry entitled As per [RFC4893], a 2-octet Autonomous System number can be converted
"Assigned transitive extended communities" with the following into a 4-octet Autonomous System number by setting the two high-order
registration procedure: octets of the 4-octet field to zero. This applies to the reserved
2-octet Autonous System number 65535 which could use either a
standard community or the 4-octet AS specific generic extended
community. As noted in
[I-D.ietf-idr-as4octet-extcomm-generic-subtype], this is undesirable
as they would be treated as different communities, even if they had
the same values.
Registry Name: Assigned transitive extended communities Therefore, this document does not define a non-transitive extended
community registry and transitive communities are still to be
assigned as per [RFC1997].
Range Registration Procedures 4. IANA Considerations
----------- -------------------------
0x0000-8000 First Come First Served
0x8001-FFFF Standards Action/Early IANA Allocation
The IANA is requested to create and maintain a registry entitled The IANA is requested to create and maintain a registry entitled
"Assigned non-transitive extended communities" with the following "Assigned non-transitive extended communities" with the following
registration procedure: registration procedure:
Registry Name: Assigned non-transitive extended communities Registry Name: Assigned non-transitive extended communities
with Global Significance
Range Registration Procedures Range Registration Procedures
----------- ------------------------- ----------- -------------------------
0x0000-8000 First Come First Served 0x0000-8000 First Come First Served
0x8001-FFFF Standards Action/Early IANA Allocation 0x8001-FFFF Standards Action/Early IANA Allocation
An application may need both a transitive and a non-transitive An application may need both a transitive and a non-transitive
community and it may be beneficial to have the same value for both community and it may be beneficial to have the same value for both
communities. (Note that both extended communities will still be communities. Therefore, the IANA SHOULD try to accommodate such
different as they will differ from their T bit). The IANA SHOULD try request to get both a non-transitive community from the above
to accommodate such request to get both a transitive and non- "Assigned non transitive extended communities" and a transitive
transitive assigned community with the same value for both. community from [RFC1997] BGP Well-known Communities with the same
(lower two-octets) value for both.
4. Security Considerations 5. Security Considerations
This document defines IANA actions. In itself, it has no impact on This document defines IANA actions. In itself, it has no impact on
the security of the BGP protocol. the security of the BGP protocol.
5. Normative References It allows the allocation of non-transitive global communities which
are not propagated across Autonomous System boundaries. Compared to
a transitive well-known community, a non-transitive community can
provide some security benefit both for the sender and the receiver of
the community.
6. Acknowledgements
We would like to acknowledge John Scudder and Jeffrey Haas for their
contribution to this document.
7. Normative References
[I-D.ietf-idr-as4octet-extcomm-generic-subtype] [I-D.ietf-idr-as4octet-extcomm-generic-subtype]
Rao, D., Mohapatra, P., and J. Haas, "Generic Subtype for Rao, D., Mohapatra, P., and J. Haas, "Generic Subtype for
BGP Four-octet AS specific extended community", BGP Four-octet AS specific extended community",
draft-ietf-idr-as4octet-extcomm-generic-subtype-04 (work draft-ietf-idr-as4octet-extcomm-generic-subtype-05 (work
in progress), July 2011. in progress), March 2012.
[RFC1997] Chandrasekeran, R., Traina, P., and T. Li, "BGP [RFC1997] Chandrasekeran, R., Traina, P., and T. Li, "BGP
Communities Attribute", RFC 1997, August 1996. Communities Attribute", RFC 1997, August 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006. Communities Attribute", RFC 4360, February 2006.
[RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS
Number Space", RFC 4893, May 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
Appendix A. Appendix A. Changes / Author Notes
[RFC Editor: Please remove this section before publication ]
Changes -01
o Name changed from 'Reserved BGP extended communities' to 'Assigned
BGP extended communities'
o Addition of section 'Assigned extended communities'
Changes -02: no change, refresh only.
Changes -03
o Use of AS number 0.65535 (0x0000FFFF) instead of AS 0. This is
better aligned with RFC 1997 which also uses AS 65535.
o Remove the transitive flavor of assigned extended communities.
RFC 1997 well-known standard communities to be used instead.
Authors' Addresses Authors' Addresses
Bruno Decraene Bruno Decraene
France Telecom - Orange France Telecom - Orange
38 rue du General Leclerc 38 rue du General Leclerc
Issy Moulineaux cedex 9 92794 Issy Moulineaux cedex 9 92794
France France
Email: bruno.decraene@orange.com Email: bruno.decraene@orange.com
 End of changes. 26 change blocks. 
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