Network Working Group A. Lindem Internet-Draft Redback Networks Intended status: Standards Track A. Roy Expires: May 6, 2008 Cisco Systems S. Mirtorabi Force10 Networks November 3, 2007 OSPF Transport Instance Extensions draft-acee-ospf-transport-instance-00.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 May 6, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Lindem, et al. Expires May 6, 2008 [Page 1] Internet-Draft OSPF Transport Instance Extensions November 2007 Abstract OSPFv2 and OSPFv3 include a reliable flooding mechanism to disseminate routing topology and Traffic Engineering (TE) information within a routing domain. Given the effectiveness of these mechanisms, it is convenient to envision using the same mechanism for dissemination of other types of information within the domain. However, burdening OSPF with this additional information will impact intra-domain routing convergence and possibly jeopardize the stability of the OSPF routing domain. This document presents mechanism to relegate this ancillary information to a separate OSPF instance and minimize the impact. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3 2. OSPF Transport Instance . . . . . . . . . . . . . . . . . . . 4 2.1. OSPFv2 Transport Instance Packets Differentiation . . . . 4 2.2. OSPFv3 Transport Instance Packets Differentiation . . . . 4 2.3. Instance Relationship to Normal OSPF Instances . . . . . . 4 2.3.1. Ships in the Night Relationship to Normal OSPF Instances . . . . . . . . . . . . . . . . . . . . . . 4 2.3.2. Child-Parent Relationship to Normal OSPF Instances . . 5 2.4. Network Prioritization . . . . . . . . . . . . . . . . . . 5 3. OSPF Transport Instance Information Encoding . . . . . . . . . 6 3.1. OSPFv2 Transport Instance Information Encoding . . . . . . 6 3.2. OSPFv3 Transport Instance Information Encoding . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. Normative References . . . . . . . . . . . . . . . . . . . . . 9 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . . . 12 Lindem, et al. Expires May 6, 2008 [Page 2] Internet-Draft OSPF Transport Instance Extensions November 2007 1. Introduction OSPFv2 [OSPFV2] and OSPFv3 [OSPFV3] include a reliable flooding mechanism to disseminate routing topology and Traffic Engineering (TE) information within a routing domain. Given the effectiveness of these mechanisms, it is convenient to envision using the same mechanism for dissemination of other types of information within the domain. However, burdening OSPF with this additional information will impact intra-domain routing convergence and possibly jeopardize the stability of the OSPF routing domain. This document presents mechanism to relegate this ancillary information to a separate OSPF instance and minimize the impact. 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 May 6, 2008 [Page 3] Internet-Draft OSPF Transport Instance Extensions November 2007 2. OSPF Transport Instance In order to isolate the overhead of flooding non-routing information, its flooding will be relegated to a separate protocol instance. This instance should be given lower priority when contending for router resources including processing, backplane bandwidth, and line card bandwidth. How that is realized is an implementation issue and is beyond the scope of this document. 2.1. OSPFv2 Transport Instance Packets Differentiation OSPFv2 currently doesn't offer a mechanism to differentiate Transport instance packets from normal instance packets sent and received on the same interface. However, the [MULTI-INST] provides the necessary packet encoding to support multiple OSPF protocol instances. 2.2. OSPFv3 Transport Instance Packets Differentiation Fortunately, OSPFv3 already supports separate instances within the packet encodings. The existing OSPFv3 packet header instance ID field will be used to differentiate packets received on the same link (refer to section 2.4 in [OSPFV3]). 2.3. Instance Relationship to Normal OSPF Instances There are basically two alternatives for the relationship between a normal OSPF instance and a Transport Instance. In both cases, we must guarantee that any information we've received is treated as valid if and only if the router sending it is reachable. We'll refer to this as the "condition of reachability" in this document. 1. Ships in the Night - The Transport Instance has no relationship or dependency on any other OSPF instance. 2. Child Instance - The Transport Instance has a child-parent relationship with a normal OSPF instance and is dependent on this for topology information and assuring the "condition of reachability". 2.3.1. Ships in the Night Relationship to Normal OSPF Instances In this mode, the Transport Instance is not dependent on any other OSPF instance. It does, however, have much of the overhead as topology information must be advertised to satisfy the condition of reachability. Prefix information does this need to be advertised. This implies that for OSPFv2, only router-LSAs, network-LSAs, and type 4 summary- Lindem, et al. Expires May 6, 2008 [Page 4] Internet-Draft OSPF Transport Instance Extensions November 2007 LSAs need to be advertised. In the router-LSAs, the stub (type 3) links may be suppressed. For OSPFv3, this implies that router-LSAs, Network-LSAs, and inter-area-router-LSAs must be advertised. 2.3.2. Child-Parent Relationship to Normal OSPF Instances In this mode, the Transport Instance will establish neighbor adjacencies the same as a normal instance. However, no topology information will be flooded or included in the database exchange process. Additionally, the Transport Instance will be dependent on its parent instance to verify the "condition a reachability" for an OSPF router advertising non-routing information. Other optimizations are possible as well. For example, the Transport Instance need not send hellos on a given interface if the are no known state 1-Way or greater neighbors in the parent instance. However, optimizations such as these are beyond the scope of this document. 2.4. Network Prioritization While OSPFv2 (section 4.3 in [OSPFV2]) are normally sent with IP precedence Internetwork Control, any packets sent by a transport instance will be sent with IP precedence Flash (B'011'). This is only appropriate given that this is a pretty flashy mechanism. OSPFv3 packet prioritization is under discussion although it is not in the current specification ([OSPFV3]). It is expected that this will be in the next revision of the OSPFv3 specification. Lindem, et al. Expires May 6, 2008 [Page 5] Internet-Draft OSPF Transport Instance Extensions November 2007 3. OSPF Transport Instance Information Encoding The format of the TLVs within the body of an LSA containing non- routing information is the same as the format used by the Traffic Engineering Extensions to OSPF [TE]. The LSA payload consists of one or more nested Type/Length/Value (TLV) triplets. The format of each TLV is: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Format However, each unique application using the mechanisms defined in this document will have it's own unique ID. Whether to encode this ID as the top-level TLV or make it part of the OSPF LSA ID is open for debate. The specific TLVs and sub-TLVs relating to a given application and the corresponding IANA considerations MUST for standard applications MUST be specified in the document corresponding to that application. 3.1. OSPFv2 Transport Instance Information Encoding Application specific information will be flooded in opaque LSAs as specified in [OPAQUE]. 3.2. OSPFv3 Transport Instance Information Encoding Application specific information will be flooded in separate LSAs with separate function codes. Refer to section A.4.2.1 of [OSPFV3] for information on the LS Type encoding in OSPFv3. Lindem, et al. Expires May 6, 2008 [Page 6] Internet-Draft OSPF Transport Instance Extensions November 2007 4. Security Considerations The security considerations for the Transport Instance will not be different for those for OSPFv2 [OSPFV2] and OSPFv3 [OSPFV3]. Lindem, et al. Expires May 6, 2008 [Page 7] Internet-Draft OSPF Transport Instance Extensions November 2007 5. IANA Considerations No new IANA assignments are required for this draft. Lindem, et al. Expires May 6, 2008 [Page 8] Internet-Draft OSPF Transport Instance Extensions November 2007 6. Normative References [MULTI-INST] Lindem, A., Mirtorabi, S., and A. Roy, "OSPF Multi- Instance Extensions", draft-acee-ospf-multi-instance-00.txt (work in progress). [OPAQUE] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, July 1998. [OSPFV2] Moy, J., "OSPF Version 2", RFC 2328, April 1998. [OSPFV3] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6", RFC 2740, December 1999. [RFC-KEYWORDS] Bradner, S., "Key words for use in RFC's to Indicate Requirement Levels", RFC 2119, March 1997. [TE] Katz, D., Yeung, D., and K. Kompella, "Traffic Engineering Extensions to OSPF", RFC 3630, September 2003. Lindem, et al. Expires May 6, 2008 [Page 9] Internet-Draft OSPF Transport Instance Extensions November 2007 Appendix A. Acknowledgments The RFC text was produced using Marshall Rose's xml2rfc tool. Lindem, et al. Expires May 6, 2008 [Page 10] Internet-Draft OSPF Transport Instance Extensions November 2007 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 May 6, 2008 [Page 11] Internet-Draft OSPF Transport Instance Extensions November 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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. 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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 May 6, 2008 [Page 12]