Network Working Group Luca Martini
Internet Draft Keyur Patel
Expiration Date: April 2007 Cisco Systems Inc.
October 2006
Route Distinguisher Zero Value Usage
draft-martini-l3vpn-rd-zero-00.txt
Status of this Memo
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Abstract
The behaviour that must be followed when an route distinguisher (RD)
of value zero is received is not clearly defined in rfc4364. This
document clarifies the use of an RD with a value of zero in the
context defined in rfc 4364.
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Table of Contents
1 Specification of Requirements ........................ 2
2 Introduction ......................................... 2
3 RFC4364 definitions .................................. 2
3.1 Usage of RD value of zero ........................... 3
4 Full Copyright Statement ............................. 3
5 Intellectual Property Statement ...................... 3
6 IANA Considerations .................................. 4
7 Normative References ................................. 4
8 Author Information ................................... 4
1. Specification of Requirements
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.
2. Introduction
This document refines the Route Distinguisher semantics detailed in
[RFC4364]. The Route Distinguisher consist of an 8-byte value whose
encoding is detailed in [RFC4364]. The Route Distinguisher is used in
conjunction with VPN prefixes and VPN nexthops in VPN networks to
solely allow one to create distinct routes to a common IPv4 address
prefix.
3. RFC4364 definitions
Currently in [RFC4364] section 4.3.2, the RD is used with a value of
0 in the next hop field of the BGP NLRI. This is a special case that
is allowed by the design. In section 4.2 of [RFC4364], the enconding
of the RD for type 0 is defines as a type field , and a value field.
If the type field is 0, then the value field in interpreted as
containing an autonomous system number (ASN), and a assigned Number
subfield. The ASN cannot contain 0 as it is a reserved ASN number.
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3.1. Usage of RD value of zero
Whenever the RD is used within the VPN nexthop field of the BGP NLRI,
the RD is used with the value of 0. However whenever the RD is used
with VPN prefix field of the BGP NLRI , the Route Distinguisher MUST
never be used with the value of 0. Hence, VPN routes received with
the Route Distinguisher value of 0 MUST be discarded with an
appropriate error.
4. Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
5. Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
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this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
6. IANA Considerations
This document has no IANA Actions.
7. Normative References
[RFC4364]] "BGP/MPLS IP Virtual Private Networks (VPNs)"
E. Rosen, Y. Rekhter, RFC 4364 February 2006
8. Author Information
Luca Martini
Cisco Systems, Inc.
9155 East Nichols Avenue, Suite 400
Englewood, CO, 80112
e-mail: lmartini@cisco.com
Keyur Patel
510 McCarthy Blvd.
Milpitas , CA, 95035
e-mail: keyupate@cisco.com
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