OSPF W. Lu Internet-Draft Ericsson Intended status: Standards Track October 18, 2010 Expires: April 21, 2011 OSPF TE Extension for Area IDs draft-lu-ospf-area-tlv-00 Abstract For multi-area path computation, it is desirable to have the knowledge of the boarder areas and the corresponding boarder routers. This memo defines a TLV to the OSPF TE extensions to meet such need. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on April 21, 2011. Copyright Notice Copyright (c) 2010 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Lu Expires April 21, 2011 [Page 1] Internet-Draft OSPF TE Extension for Area IDs October 2010 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3 1.2. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Area ID TLV . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Applications . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5 Lu Expires April 21, 2011 [Page 2] Internet-Draft OSPF TE Extension for Area IDs October 2010 1. Introduction The Traffic Engineering Database (TED) based on OSPF is sufficient for the intra-area path computation. However because TED is of area scope, the path computation cannot be used for inter-area scenarios without the help of area boarder routers. Although the Router LSA offers a B bit to signify an ABR router, the identity of the attached area is unkown. This will force a router to contact every ABRs if it wants TED info from each area. West A---B---C East |\ D E South Figure 1: Sample Topology For example, as shown in Figure 1, the router B has three neighbor areas West, East, and South. It can reach these areas through ABRs A, C, D and E. Both D and E connect to the area South. Ideally B only needs to contact A, c, D (or E) to obtain TED info of the three areas. However, since it does not know that D and E share the boarder between this area and the area South, it has to blindly send the request to both D and E. If instead each ABR provides its exit area's information, such as A(West), C(East), D(South), E(South), the router B will be able to make a sound decision to utilize only three ABRs. For this purpose we define an area ID TLV, detailed in Section 2. Moreover since the TLV is for TE purpose, it is added under the OSPF TE LSA as defined in OSPF TE Extensions [RFC3630]. 1.1. Requirements Language 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]. 1.2. Acronyms ABR - Area Boarder Router Lu Expires April 21, 2011 [Page 3] Internet-Draft OSPF TE Extension for Area IDs October 2010 TE - Traffice Engineering TED - Traffice Engineering Database PCE - Path Computation Element LSP - Label Switched Path OSPF - Open Shortest Path First LSA - Link State Advertisement 2. Area ID TLV [RFC3630] section 2.4 defined two TLVs. This memo adds a third TLV, the Area ID TLV. The area ID TLV is type TBD (suggest 3), has a length of 4, and a value that is the four octet integer. It may have zero or more occurances in one Traffic Engineering LSA originated by a router. The value is the area ID of an exit area for which the ABR has TE enabled. An ABR may join multiple areas. Therefore it may generate m-1 area ID TLVs, where m is the total number of areas the router joins. For a non-ABR router, it does not have any exit area, hence its TE TLV has zero occurance of the area ID TLV. 3. Applications With the area ID TLVs in TED, when performing inter-area path computation, a PCE [RFC4655] will gain additional knowledge of the surrounding areas and the boarder routers to reach each area. The PCE may elect one boarder router for each area and request TE info from it. Alternatively, the PCE may relay the path computation job to the PCE which is also an ABR. 4. Acknowledgements TBD Lu Expires April 21, 2011 [Page 4] Internet-Draft OSPF TE Extension for Area IDs October 2010 5. IANA Considerations This document defines the following TLV to the OSPF TE Extensions under TE LSA: +-------------------+-------------+---------------+ | Type | Name | Source | +-------------------+-------------+---------------+ | TBD (recommend 3) | Area ID TLV | This document | +-------------------+-------------+---------------+ 6. Security Considerations There are no specific security considerations within the scope of this document. 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, September 2003. 7.2. Informative References [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 2006. Author's Address Wenhu Lu Ericsson 300 Holger Way San Jose, California 95134 USA Phone: 408 750-5436 Email: wenhu.lu@ericsson.com Lu Expires April 21, 2011 [Page 5]