Network Working Group K. Patel
Internet-Draft Cisco Systems
Intended status: Standards Track R. Raszuk
Expires: February 09, 2014 NTT MCL Inc.
August 08, 2013
IPv6 Extensions for Route Target Distribution
The current route target distribution specification described in
RFC4684 defines Route Target NLRIs of maximum length of 12 bytes.
The IPv6 specific Route Target extended community is defined in
[RFC5701] as length of 20 bytes. Since the current specification
only supports prefixes of maximum length of 12 bytes, the lack of an
IPv6 specific Route Target reachability information may be a problem
when an operator wants to use this application in a pure IPv6
environment. This document defines an extension that allows BGP to
exchange longer length IPv6 Route Target prefixes.
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
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Patel, et al. Expires February 09, 2014 [Page 1]Internet-Draft IPv6 Extensions for RT Distribution August 2013
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. BGP IPv6 Constrained Route Target Capability . . . . . . . . 2
3. IPv6 Constrained Route Target NLRI Advertisements . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
The current constrained route distribution specification defined in
[RFC4684] supports prefixes with a maximum length of 12 bytes. The
prefix length needs to be extended to support the IPv6 specific Route
Target extended community defined in [RFC5701] which is 20 bytes in
length. This document defines an extension to the current
constrained route distribution specification that allows BGP speakers
to distribute longer length Route Target prefixes. A new BGP
capability known as BGP IPv6 Constrained Route Target capability is
defined as part of extension that allows an exchange of longer length
Route Target prefixes. BGP speakers that do not exchange this
capability MUST use Route Target NLRIs of maximum length of 12 bytes.
In this way, the current extension would preserve the backward
compatibility with [RFC4684].
2. BGP IPv6 Constrained Route Target CapabilityPatel, et al. Expires February 09, 2014 [Page 2]Internet-Draft IPv6 Extensions for RT Distribution August 2013
The "BGP IPV6 Constrained Route Target Capability" is a new BGP
capability [RFC5492]. The Capability code for this capability is
specified in the IANA Considerations section of this document. The
Capability length field of this capability is zero.
By advertising this capability to a peer, a BGP speaker conveys to
the peer that the speaker support the longer length Route Target
prefixes and the related procedures described in this document.
3. IPv6 Constrained Route Target NLRI Advertisements
Route Target membership NLRI is advertised in BGP UPDATE messages
using the MP_REACH_NLRI and MP_UNREACH_NLRI attributes as defined in
[RFC4760]. The NLRI field in the MP_REACH_NLRI and MP_UNREACH_NLRI
is a prefix of 0 to 24 octets, encoded as defined in Section 4 of
[RFC4760] for all the constrained route distribution.
This prefix is structured as follows:
| origin as (4 octets) |
| route target (8 or 20 octets)|
Except for the default route target, which is encoded as a zero-
length prefix, the minimum prefix length is 32 bits. As the origin-
AS field cannot be interpreted as a prefix.
Route targets can then be expressed as prefixes, where, for instance,
a prefix would encompass all route target extended communities
assigned by a given Global Administrator [RFC4360] and [RFC5701].
Alternatively, route target prefixes could be aggregated however if
done so, then only the Local Administrator field of the Route Target
can be aggregated. Route Target Type and the Global Administrator
Route Target fields MUST not be aggregated.
The default route target can be used to indicate to a peer the
willingness to receive all VPN route advertisements such as, for
instance, the case of a route reflector speaking to one of its PE
4. IANA ConsiderationsPatel, et al. Expires February 09, 2014 [Page 3]Internet-Draft IPv6 Extensions for RT Distribution August 2013
This document defined the IPV6 Constrained Route Target Capability
for BGP. The Capability code needs to be assigned by the IANA.
5. Security Considerations
This extension to [RFC4684] does not change the underlying security
issues inherent in the existing BGP and [RFC4684].
The authors would like to thank Pedro Marques, John Scudder, Alton Lo
and Zhenqiang Li for discussions and review.
7. References7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006.
[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, November 2006.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, February 2009.
[RFC5701] Rekhter, Y., "IPv6 Address Specific BGP Extended Community
Attribute", RFC 5701, November 2009.
7.2. Informative References
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, January
Authors' AddressesPatel, et al. Expires February 09, 2014 [Page 4]Internet-Draft IPv6 Extensions for RT Distribution August 2013
170 W. Tasman Drive
San Jose, CA 95134
NTT MCL Inc.
101 S Ellsworth Avenue Suite 350
San Mateo, CA 94401
1194 N. Mathilda Avenue
Sunnyvale, CA 94089
Huawei Building, No.156 Beiqing Rd.
Huawei Building, No.156 Beiqing Rd.
Patel, et al. Expires February 09, 2014 [Page 5]