IDR J. Heitz
Internet-Draft K. Patel
Intended status: Standards Track Cisco
Expires: January 19, 2017 J. Snijders
NTT
I. Bagdonas
Equinix
July 18, 2016
Large BGP Community
draft-heitz-idr-large-community-01
Abstract
A new type of BGP community attribute that contains communities that
each hold a 4-octet AS number and a 6-octet opaque field is defined.
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 [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
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This Internet-Draft will expire on January 19, 2017.
Copyright Notice
Copyright (c) 2016 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Large BGP Community Attribute . . . . . . . . . . . . . . . . 2
3. 4-Octet AS Specific Large Community . . . . . . . . . . . . . 4
3.1. Textual Representation . . . . . . . . . . . . . . . . . 5
4. Equivalence with Extended Communities . . . . . . . . . . . . 5
5. RT Constraint . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Large Regular Communities . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
A BGP Community attribute is defined that encodes 14 byte
communities, suitable for 4-Octet Autonomous System Numbers that
require a 8-Octet Local Administrator field.
The 2-octet AS Specific Extended Community defined in [RFC4360] has
been widely used. 4-octet AS numbers as defined by [RFC4893] are
unable to make use of this popular extended community. Subsequently,
[RFC5668] defined a 4-octet AS Specific Extended community. However,
to make room for the extra 2 octets of AS number, the Local
Administrator field was shrunk from 4 octets to 2. This document
defines a community to extend that to 8 octets.
To ensure rapid and smooth adoption of the new community attribute,
it must be as similar to the extended community as possible, only
bigger.
2. Large BGP Community Attribute
The Large Community Attribute is a transitive optional BGP attribute,
with the Type Code (suggested 41) to be assigned by IANA. The
attribute consists of a set of "Large Communities". All routes with
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the Large Community attribute belong to the communities listed in the
attribute.
Each Large Community is encoded as a 14-octet quantity, as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I| T | Type | Sub-Type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value +
| |
+ +
| |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are as shown below:
I - IANA authority bit
Value 0: IANA-assignable type using the "First Come First
Serve" policy
Value 1: Part of this Type Field space is for IANA
assignable types using either the Standard Action or
the Early IANA Allocation policy. The rest of this
Type Field space is for Experimental use.
T - Transitivity field
Value 0: The community is transitive across all ASes.
Value 1: The community is transitive across AS boundaries,
but not across an administration boundary. An
administration in this sense is an arbitrary set of
connected ASes, possibly owned by a single
administration. How such an administration boundary
is determined is out of scope of this document.
Value 2: The community is transitive across Confederation
member AS boundaries, but not across a confederation
boundary or across an AS boundary that does not use
confederations.
Value 3: The community is not transitive across any AS
boundary, including Confederation Member AS.
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Type - 5 bits describing how the value field is divided. One
type, the 4-Octet AS Specific Large Community is described
in this document.
Sub-type - describes the meaning of the value field.
Value - The actual information according to the sub-type.
The Transitivity field is only a hint to BGP speakers that do not
implement or understand the specific community. In some cases it
makes sense to send a community across one boundary but not the next.
An example is the Link Bandwidth Extended Community.
The Transitivity field is not implicitly associated with the Type and
Sub-Type fields the way they are in Extended Communities. The
Transitivity field should be set by the originator based upon
individual circumstances at the originator
3. 4-Octet AS Specific Large Community
This is a Large Community type with a Value field comprising 12
octets.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| T | 2 | Sub-Type | Global Administrator :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Global Administrator (cont.) | Local Administrator 1 :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Local Administrator 1 (cont.) | Local Administrator 2 :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Local Administrator 2 (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The definition of each sub-type should specify how to set the T
field. The Type field is 2. The Sub-Type is to be assigned by IANA
for individual functions.
The Value field consists of 3 sub-fields:
Global Administrator sub-field: 4 octets
This sub-field contains a 4-octet Autonomous System number
assigned by IANA.
Local Administrator 1 sub-field: 4 octets
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Local Administrator 2 sub-field: 4 octets
The organization identified by the Autonomous System number in
the Global Administrator sub-field can encode any information
in these sub-fields. The format and meaning of the value
encoded in these sub-fields should be defined by the sub-type
of the community.
3.1. Textual Representation
The textual representation of the 4-Octet AS Specific Large Community
is A:B:C, where A is the Global Administrator, B is the Local
Administrator 1 and C is the Local Administrator 2. A ranges from 0
to 4294967295. B ranges from 0 to 4294967295. C ranges from 0 to
4294967295. A, B and C are plain decimal non-negative integers
without leading zeroes. Each number must appear, even if it is 0.
For example, "0:1:2" cannot be written as ":1:2".
4. Equivalence with Extended Communities
A 4-octet AS Specific Extended Community [RFC5668] is equivalent to a
4-octet AS Specific Large Community if:
o bits 1 and 2 of the Extended community Type field is equal to the
Transitivity, and
o the Sub-Types are semantically equivalent, and
o the Global Administrators are equal, and
o the Extended Community Local Administrator left shifted by 16 bits
is equal to the Local Administrator 1, and
o Local Administrator 2 is zero.
A 2-octet AS Specific Extended Community [RFC4360] is equivalent to a
4-octet AS Specific Large Community if:
o bits 1 and 2 of the Extended community Type field is equal to the
Transitivity, and
o the Sub-Types are semantically equivalent, and
o the Global Administrators are equal, and
o the Extended Community Local Administrator is equal to the Local
Administrator 1, and
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o Local Administrator 2 is zero.
If a community contains an Autonomous System Number less than 65536
and a Local Administrator value less than 2^32, then it can be
represented either as a 4-Octet AS Specific Large Community or a
2-Octet AS Specific Extended Community. These communities would be
treated as different, even though they hold the same information. To
prevent such inconsistencies, such communities SHOULD be encoded as a
2-Octet Specific Extended Community.
Similarly, if a community contains an Autonomous System Number
greater than 65535 and a Local Administrator value less than 65536,
then it SHOULD be encoded as a 4-Octet AS Specific Extended Community
as per [RFC5668].
5. RT Constraint
RT Constraint is defined in [RFC4684]. If RT Constraint is to be
used with Large Community Route Targets, then the maximum length of
an RT Constraint prefix needs to be increased to 144 bits.
An RT Constraint prefix made from a 4-Octet AS Specific Extended
Community is directly comparable to an RT Constraint prefix made from
a 4-Octet AS Specific Large Community
6. Large Regular Communities
The AS portion of BGP Communities described in [RFC1997] is too small
to fit a 4-octet ASN.
[I-D.ietf-idr-as4octet-extcomm-generic-subtype] defines an Extended
Community sub-type to perform the same function with a 4-octet ASN.
Large Communities will provide the same functionality, but provide an
extra 6 octets of Local Administrator space.
7. Security Considerations
TBD
8. IANA Considerations
IANA is requested to assign a BGP path attribute value for the Large
community attribute.
IANA is requested to create and maintain a registry for the Type
field of the Large Community. This document reserves the Type value
0 for the 4-Octet AS Specific Large Community.
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IANA is requested to create and maintain a registry for the Sub-Type
field of the 4-Octet AS Specific Large Community. The initial values
in the registry should be the same as those in the registry for the
2-octet AS Specific Extended Community. These values are reproduced
as follows:
0x02 Route Target [RFC4360]
0x03 Route Origin [RFC4360]
0x04 Link Bandwidth [I-D.ietf-idr-link-bandwidth]
0x05 OSPF Domain Identifier [RFC4577]
0x08 BGP Data Collection [RFC4384]
0x09 Source AS [RFC6514]
0x0a L2VPN Identifier [RFC6074]
0x10 Cisco VPN-Distinguisher [Eric_Rosen]
0x80 Virtual-Network Identifier Extended Community
[I-D.drao-bgp-l3vpn-virtual-network-overlays]
As the generic sub-type defined in
[I-D.ietf-idr-as4octet-extcomm-generic-subtype] is 4 and clashes with
the value for the Link Bandwidth, IANA is requested to assign a new
value.
9. Acknowledgements
Thanks to Russ White, Acee Lindem and Shyam Sethuram for insightful
review and comments.
10. References
10.1. Normative References
[I-D.ietf-idr-as4octet-extcomm-generic-subtype]
Rao, D., Mohapatra, P., and J. Haas, "Generic Subtype for
BGP Four-octet AS specific extended community", draft-
ietf-idr-as4octet-extcomm-generic-subtype-08 (work in
progress), June 2015.
[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities
Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
<http://www.rfc-editor.org/info/rfc1997>.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <http://www.rfc-editor.org/info/rfc4360>.
[RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk,
R., Patel, K., and J. Guichard, "Constrained Route
Distribution for Border Gateway Protocol/MultiProtocol
Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual
Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684,
November 2006, <http://www.rfc-editor.org/info/rfc4684>.
[RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS
Number Space", RFC 4893, DOI 10.17487/RFC4893, May 2007,
<http://www.rfc-editor.org/info/rfc4893>.
[RFC5668] Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS
Specific BGP Extended Community", RFC 5668,
DOI 10.17487/RFC5668, October 2009,
<http://www.rfc-editor.org/info/rfc5668>.
10.2. Informative References
[I-D.drao-bgp-l3vpn-virtual-network-overlays]
Rao, D., Mullooly, J., and R. Fernando, "Layer-3 virtual
network overlays based on BGP Layer-3 VPNs", draft-drao-
bgp-l3vpn-virtual-network-overlays-03 (work in progress),
July 2014.
[I-D.ietf-idr-link-bandwidth]
Mohapatra, P. and R. Fernando, "BGP Link Bandwidth
Extended Community", draft-ietf-idr-link-bandwidth-06
(work in progress), January 2013.
[RFC4384] Meyer, D., "BGP Communities for Data Collection", BCP 114,
RFC 4384, DOI 10.17487/RFC4384, February 2006,
<http://www.rfc-editor.org/info/rfc4384>.
[RFC4577] Rosen, E., Psenak, P., and P. Pillay-Esnault, "OSPF as the
Provider/Customer Edge Protocol for BGP/MPLS IP Virtual
Private Networks (VPNs)", RFC 4577, DOI 10.17487/RFC4577,
June 2006, <http://www.rfc-editor.org/info/rfc4577>.
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[RFC6074] Rosen, E., Davie, B., Radoaca, V., and W. Luo,
"Provisioning, Auto-Discovery, and Signaling in Layer 2
Virtual Private Networks (L2VPNs)", RFC 6074,
DOI 10.17487/RFC6074, January 2011,
<http://www.rfc-editor.org/info/rfc6074>.
[RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
Encodings and Procedures for Multicast in MPLS/BGP IP
VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012,
<http://www.rfc-editor.org/info/rfc6514>.
Authors' Addresses
Jakob Heitz
Cisco
170 West Tasman Drive
San Jose, CA 95054
USA
Email: jheitz@cisco.com
Keyur Patel
Cisco
170 West Tasman Drive
San Jose, CA 95054
USA
Email: keyupate@cisco.com
Job Snijders
NTT Communications, Inc.
Theodorus Majofskistraat 100
Amsterdam 1065 SZ
NL
Email: job@ntt.net
Ignas Bagdonas
Equinix
London
UK
Email: ibagdona.ietf@gmail.com
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