Network Working Group A. Lindem
Internet-Draft Redback Networks
Intended status: Standards Track A. Roy
Expires: August 17, 2008 Cisco Systems
S. Mirtorabi
Force10 Networks
February 14, 2008
OSPF Multi-Instance Extensions
draft-acee-ospf-multi-instance-01.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 17, 2008.
Copyright Notice
Copyright (C) The IETF Trust (2008).
Lindem, et al. Expires August 17, 2008 [Page 1]
Internet-Draft OSPF Multi-Instance Extensions February 2008
Abstract
OSPFv3 includes a mechanism for supporting multiple instances on the
same link. OSPFv2 could benefit from such a mechanism in order to
support multiple routing domains on the same subnet. The OSPFv2
instance ID is reserved for support of separate OSPFv2 protocol
instances. This is different from OSPFv3 where it could be used for
other purposes such as putting the same link in multiple areas.
OSPFv2 supports this capability using a separate subnet or the OSPF
multi-area adjacency capability.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3
2. OSPFv2 Instance Packet Encoding . . . . . . . . . . . . . . . 4
3. OSPF Interface Instance ID . . . . . . . . . . . . . . . . . . 6
3.1. Sending and Receiving OSPF packets . . . . . . . . . . . . 6
4. Backward Compatibility and Deployment Considerations . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Normative References . . . . . . . . . . . . . . . . . . . . . 10
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
Intellectual Property and Copyright Statements . . . . . . . . . . 13
Lindem, et al. Expires August 17, 2008 [Page 2]
Internet-Draft OSPF Multi-Instance Extensions February 2008
1. Introduction
OSPFv3 [OSPFV3] includes a mechanism for supporting multiple
instances on the same link. OSPFv2 [OSPFV2] could benefit from such
a mechanism in order to support multiple routing domains on the same
subnet. The OSPFv2 instance ID is reserved for support of separate
OSPFv2 protocol instances. This is different from OSPFv3 where it
could be used for other purposes such as putting the same link in
multiple areas. OSPFv2 supports this capability using a separate
subnet or the OSPF multi-area adjacency capability [MULTI-AREA].
1.1. Requirements notation
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-KEYWORDS].
Lindem, et al. Expires August 17, 2008 [Page 3]
Internet-Draft OSPF Multi-Instance Extensions February 2008
2. OSPFv2 Instance Packet Encoding
OSPFv2 currently doesn't offer a mechanism to differentiate packets
for different instances sent and received on the same interface. In
support of this capability, this document introduces a modified
packet header format when the Authentication Type field is split into
an instance ID and type.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version # | Type | Packet length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Checksum | Instance ID | AuType |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Authentication |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Authentication |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The OSPFv2 Packet Header
Version #
The OSPFv2 version number - 2
Type
The OSPFv2 packet type as specified [OSPFV2].
Packet length
The length of the OSPF protocol packet in bytes. This length
includes the standard OSPF header.
Router ID
The Router ID of the packet's source.
Area ID
A 32-bit number identifying the area corresponding the packet as
specified in [OSPFV2].
Lindem, et al. Expires August 17, 2008 [Page 4]
Internet-Draft OSPF Multi-Instance Extensions February 2008
Checksum
OSPFv2 standard checksum calculation as specified in specified in
[OSPFV2].
Instance ID
Enables multiple instances of OSPF to be run over a single link.
Each protocol instance would be assigned a separate Instance ID;
the Instance ID has local subnet significance only. Received
packets with an Instance ID not equal to one of the configured
OSPF Instance IDs on the receiving interface MUST be discarded.
AuType
OSPFv2 authentication type as specified in specified in [OSPFV2].
Authentication
A 64-bit field for Authentication type dependent authentication
data.
Lindem, et al. Expires August 17, 2008 [Page 5]
Internet-Draft OSPF Multi-Instance Extensions February 2008
3. OSPF Interface Instance ID
OSPF [OSPFV2] describes the conceptual interface data structure in
section 9. The OSPF Interface ID will be added to this structure.
The Interface Instance ID will default to 0. Its setting to a non-
zero value may be accomplished through configuration or implied by
some usage beyond the scope of this document.
3.1. Sending and Receiving OSPF packets
When sending OSPF packets, if the interface instance ID has a non-
zero value, it will be set in the OSPF packet header. When receiving
OSPF packets, the OSPFv2 Header Instance ID will be used to aid in
demultiplexing the packet and routing it to the correct OSPFv2
instance. Received packets with an Instance ID not equal to one of
the configured OSPF Instance IDs on the receiving interface MUST be
discarded.
Lindem, et al. Expires August 17, 2008 [Page 6]
Internet-Draft OSPF Multi-Instance Extensions February 2008
4. Backward Compatibility and Deployment Considerations
When there are OSPF routers that support this capability on the same
broadcast capable link as those that do not, packets with non-zero
Instance IDs will be received by those legacy routers. Since the
authentication type will be unknown to them they will not process the
packet. This is exactly what is desired.
Previously, a concern was that some implementations will log every
single authentication type mismatch. However, discussions with
implementers have led us to the conclusion that this is not as
current a problem as we'd first thought and it will be even less of a
problem by the time the mechanism in this draft is standardized,
implemented, and deployed. Hence, the controversial mechanisms to
avoid legacy routers receiving multicast OSPF packets with a non-zero
instance ID have been removed.
Lindem, et al. Expires August 17, 2008 [Page 7]
Internet-Draft OSPF Multi-Instance Extensions February 2008
5. Security Considerations
The enhancement described herein doesn't add any additional security
considerations to OSPFv2. Security considerations for OSPFv2 are
described in [OSPFV2].
Given that only three OSPFv2 authentication types have been
standardized, it seems reasonable to reduce the OSPF packet header
field to 8 bits.
Lindem, et al. Expires August 17, 2008 [Page 8]
Internet-Draft OSPF Multi-Instance Extensions February 2008
6. IANA Considerations
A new registry will be added for OSPF Instance IDs. The allocation
is TBD.
Dependent on the approach, two new multicast addresses from the IPv4
Multicast Addresses registry would need to be allocated.
Dependent on the approach, a new protocol ID may need to be allocated
from the Protocol Numbers registry.
Lindem, et al. Expires August 17, 2008 [Page 9]
Internet-Draft OSPF Multi-Instance Extensions February 2008
7. Normative References
[MULTI-AREA]
Mirtorabi, S., Psenak, P., Lindem, A., and A. Oswal, "OSPF
Multi-Area Adjacency",
draft-ietf-ospf-multi-area-adj-07.txt (work in progress).
[OSPFV2] Moy, J., "OSPF Version 2", RFC 2328, April 1998.
[OSPFV3] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
RFC 2740, April 2007.
[RFC-KEYWORDS]
Bradner, S., "Key words for use in RFC's to Indicate
Requirement Levels", RFC 2119, March 1997.
Lindem, et al. Expires August 17, 2008 [Page 10]
Internet-Draft OSPF Multi-Instance Extensions February 2008
Appendix A. Acknowledgments
The RFC text was produced using Marshall Rose's xml2rfc tool.
Thanks to Paul Wells for commenting on the backward compatibility
issues.
Lindem, et al. Expires August 17, 2008 [Page 11]
Internet-Draft OSPF Multi-Instance Extensions February 2008
Authors' Addresses
Acee Lindem
Redback Networks
102 Carric Bend Court
Cary, NC 27519
USA
Email: acee@redback.com
Abhay Roy
Cisco Systems
225 West Tasman Drive
San Jose, CA 95134
USA
Email: akr@cisco.com
Sina Mirtorabi
Force10 Networks
350 Holger Way
San Jose, CA 95134
USA
Email: sina@force10networks.com
Lindem, et al. Expires August 17, 2008 [Page 12]
Internet-Draft OSPF Multi-Instance Extensions February 2008
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
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, THE IETF TRUST 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.
Intellectual Property
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
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
Lindem, et al. Expires August 17, 2008 [Page 13]