Network Working Group A. Lindem Internet-Draft Ericsson Intended status: Standards Track A. Roy Expires: April 6, 2010 S. Mirtorabi Cisco Systems October 3, 2009 OSPF Multi-Instance Extensions draft-ietf-ospf-multi-instance-01.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 April 6, 2010. Copyright Notice Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Lindem, et al. Expires April 6, 2010 [Page 1] Internet-Draft OSPF Multi-Instance Extensions October 2009 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. State Sharing Optimizations between OSPF instances . . . . . . 7 5. Backward Compatibility and Deployment Considerations . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 8. Normative References . . . . . . . . . . . . . . . . . . . . . 11 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Lindem, et al. Expires April 6, 2010 [Page 2] Internet-Draft OSPF Multi-Instance Extensions October 2009 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 April 6, 2010 [Page 3] Internet-Draft OSPF Multi-Instance Extensions October 2009 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 April 6, 2010 [Page 4] Internet-Draft OSPF Multi-Instance Extensions October 2009 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 April 6, 2010 [Page 5] Internet-Draft OSPF Multi-Instance Extensions October 2009 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 April 6, 2010 [Page 6] Internet-Draft OSPF Multi-Instance Extensions October 2009 4. State Sharing Optimizations between OSPF instances This is beyond the scope of this draft and is an area for further study. Lindem, et al. Expires April 6, 2010 [Page 7] Internet-Draft OSPF Multi-Instance Extensions October 2009 5. 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 April 6, 2010 [Page 8] Internet-Draft OSPF Multi-Instance Extensions October 2009 6. 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 April 6, 2010 [Page 9] Internet-Draft OSPF Multi-Instance Extensions October 2009 7. 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 April 6, 2010 [Page 10] Internet-Draft OSPF Multi-Instance Extensions October 2009 8. Normative References [MULTI-AREA] Mirtorabi, S., Psenak, P., Lindem, A., and A. Oswal, "OSPF Multi-Area Adjacency", RFC 5185, May 2008. [OSPFV2] Moy, J., "OSPF Version 2", RFC 2328, April 1998. [OSPFV3] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, July 2008. [RFC-KEYWORDS] Bradner, S., "Key words for use in RFC's to Indicate Requirement Levels", RFC 2119, March 1997. Lindem, et al. Expires April 6, 2010 [Page 11] Internet-Draft OSPF Multi-Instance Extensions October 2009 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 April 6, 2010 [Page 12] Internet-Draft OSPF Multi-Instance Extensions October 2009 Authors' Addresses Acee Lindem Ericsson 102 Carric Bend Court Cary, NC 27519 USA Email: acee.lindem@ericsson.com Abhay Roy Cisco Systems 225 West Tasman Drive San Jose, CA 95134 USA Email: akr@cisco.com Sina Mirtorabi Cisco Systems 3 West Plumeria Drive San Jose, CA 95134 USA Email: sina@cisco.com Lindem, et al. Expires April 6, 2010 [Page 13]