Network work group Mach Chen Renhai Zhang Internet Draft Huawei Technologies Co.,Ltd Expires: July 2007 January 30, 2007 OSPF Extensions in Support of Inter-AS (G)MPLS TE draft-chen-ccamp-ospf-interas-te-extension-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 July 30, 2007. Abstract This document describes extensions to the OSPF to support inter-AS Traffic engineering (TE). It defines OSPF extensions for the flooding of inter-AS links information which can be used to perform inter-AS path computation. Conventions used in this document 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. Mach & Renhai Expires July 30, 2007 [Page 1] Internet-Draft Inter-AS Links connection information January 2007 Table of Contents 1. Introduction.................................................2 2. Problem statement............................................3 3. Extensions to OSPF...........................................4 3.1. Remote AS number sub-TLV................................4 3.2. Inter-AS Link type......................................5 3.3. Link ID.................................................5 4. Inter-AS links procedure.....................................5 5. Security Considerations......................................5 6. IANA Considerations..........................................6 6.1. Sub-TLVs types..........................................6 6.2. Link types..............................................6 7. References...................................................7 7.1. Normative References....................................7 7.2. Informative References..................................7 Author's Addresses..............................................8 Intellectual Property Statement.................................8 Disclaimer of Validity..........................................9 Copyright Statement.............................................9 Acknowledgment..................................................9 1. Introduction [OSPF-TE] defines extensions to the OSPF to support intra-area Traffic Engineering (TE). The extensions provide a way of describing the Traffic Engineering information and flooding this information within an area. Type 10 opaque LSA is used to carry such TE information. Two top-level TLVs are defined in [OSPF-TE]: Router Address TLV and Link TLV, the Link TLV has several nested sub-TLVs which describe the TE attribute for a TE enabled link. A node advertises this TE information only if an IGP adjacency is established over an intra-area link. Inter-AS MPLS TE requirements are described in [INTERAS-TE-REQ]. As described in [INTERAS-TE-REQ], a method SHOULD provide the ability to compute a path spanning multiple ASes. So a path computation entity (Head/Tail-end, ASBR or PCE) needs to know the TE information of not only the links within an AS, but also the links that connect to other ASes. In this document, some extensions to [OSPF-TE] are defined in support of carrying and flooding inter-AS links information for inter-AS Traffic Engineering. A new sub-TLV is added to the Link TLV and a new link type is introduced. The detailed definitions and procedures are provided in the following sections. Mach & Renhai Expires July 30, 2007 [Page 2] Internet-Draft Inter-AS Links connection information January 2007 2. Problem statement As described in [INTERAS-TE-REQ], in the case of establishing an inter-AS TE LSP which traverses multiple ASes, the signaling protocol may contain the following elements in the Explicit Route Object(ERO): -a set of AS numbers as loose hop and/or -a set of LSRs including ASBRs In per domain method, when each entry LSR within an AS receives a PATH message from the upstream AS with the ERO containing a sequence of ASes, it SHOULD be able to find which LSRs within the local AS are connected to the downstream AS, therefore compute a TE LSP segment to that LSR, and pass this PATH message to it. See the below figure for example: R1-----R3-----R5-----R6------R9-----R11 | | / \ | | R2-----R4--- ----R8------R10----R12 <=AS 1=> <==AS 2= > <=AS 3=> Figure 1: Inter-AS Reference Model If an inter-AS TE LSP is to be established from R1 within AS 1 to R12 within AS 3, the AS sequence will be traversed as: AS1, AS2 and AS3. The PATH message is constructed and sent from R1. When R5 within AS 2 receives the PATH message, R5 SHOULD firstly be able to determine that there are two ASBRs and two inter-AS links connected to AS 3, then R5 SHOULD be able to choose a feasible route to the entry LSR(R9 or R10) within AS 3. To make these abilities possible for R5, besides the usual TE database information including the inter-AS TE links (R6-R9, R8-R10), R5 SHOULD also maintain the following information for each inter-AS TE link: -an indication that this is an inter-AS link -the neighboring AS -the neighboring ASBR in the neighboring AS This information is needed throughout the local AS if path computation function is fully distributed among LSRs within the local AS. Another scenario using PCE technique also has the above problem. [BRPC] defines a PCE-based TE LSP computation method to compute optimal inter-domain constrained (G)MPLS TE LSPs. In this path computation method, a set of specific traversed domains are assumed Mach & Renhai Expires July 30, 2007 [Page 3] Internet-Draft Inter-AS Links connection information January 2007 to be selected before the computation starts. Each downstream PCE in domain(i) SHOULD return a VSPT to the upstream PCE in domain(i-1), where VSPT is a MP2P tree from Boundary Nodes located in domain(i) to the destination that satisfies the set of required constraints for the TE LSP (bandwidth, affinities, ...). So a PCE needs to locate Boundary Nodes that provide connectivity from a specified AS. For inter-AS TE stated in this document, the PCE MUST have the knowledge of inter-AS links information to locate the ASBRs connected with remote ASes. An extension to IGP is introduced in this draft to flood inter-AS links information among LSRs within the local AS. BGP extension to flood this information for PCE is out of scope of this document. 3. Extensions to OSPF In this document, we use the Type 11 Opaque LSAs, which have an AS flooding scope. That is, inter-AS TE links SHOULD be flooded within a whole AS, each router in the AS can receive those inter-AS TE links and can use such information for inter-AS path computation. 3.1. Remote AS number sub-TLV As described in [OSPF-TE], the Link TLV describes a single link and it consists of a set of sub-TLVs. In this document, a new sub-TLV, Remote AS number sub-TLV is added to the Link TLV when advertising inter-AS links. The Remote AS number sub-TLV specifies the AS number of the neighboring AS corresponding to this link. The Remote AS number sub-TLV is TLV type 18 (which needs to be confirmed by IANA), and is four octets in length. The format is as follows: 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote AS Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Remote AS number field has 4 octets, when two octets are used for AS number in current implementation, the left two octets MUST be set to zero. Mach & Renhai Expires July 30, 2007 [Page 4] Internet-Draft Inter-AS Links connection information January 2007 3.2. Inter-AS Link type To identify a link to be an inter-AS link, a new Link type, inter-AS link is specified, the value of inter-AS link type is 3 (which needs to be confirmed by IANA). 3.3. Link ID For an inter-AS link, the Link ID is the remote ASBR Router ID corresponding to this inter-AS link. 4. Inter-AS links procedure Although there is no OSPF adjacency running over an inter-AS link, the ASBR SHOULD advertise this link to all nodes within its AS when TE is enabled on the link and the link is up. When either the link is down or TE is disabled on the link, the ASBR SHOULD withdraw the advertisement. As a result of such advertisement, all nodes in that AS will get those inter-AS links information. An AS Boundary Connection table COULD be established to efficiently maintain those information. Each table entry SHOULD at least consist of Router ID of Local ASBR, Router ID of remote ASBR, Remote AS number. Take Figure 1 for example again, AS Boundary Connect table of R5 should include such information as below: Remote AS number Local Router ID Remote Router ID -------------------------------------------------- AS1 R5 R3 AS1 R5 R4 AS3 R6 R9 AS3 R8 R10 Table 1: The AS Boundary Connect table for R5 By looking up this table, a path computation entity can identify an ASBR to reach the next AS. PCE can also identify all ASBRs connected to a specified AS. 5. Security Considerations This extension to OSPF does not change the underlying security issues. Mach & Renhai Expires July 30, 2007 [Page 5] Internet-Draft Inter-AS Links connection information January 2007 6. IANA Considerations 6.1. Sub-TLVs types Value Meaning 18 Remote AS number sub-TLV. 6.2. Link types Value Meaning 3 inter-AS link type. Mach & Renhai Expires July 30, 2007 [Page 6] Internet-Draft Inter-AS Links connection information January 2007 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. [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC2370] R. Coltun, "The OSPF Opaque LSA Option", RFC2370, July 1998. [OSPF] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [INTERAS-TE-REQ] Zhang and Vasseur, "MPLS Inter-AS Traffic Engineering Requirements", RFC4216, November 2005. [OSPF-TE] Katz, D., Kompella, K., and Yeung, D., "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, September 2003. [CCAMP-INTER-DOMAIN-TE] Ayyangar, A. and J. Vasseur, "Inter domain GMPLS Traffic Engineering - RSVP-TE extensions",draft-ietf- ccamp-inter-domain-rsvp-te-04 (work in progress), January 2007. 7.2. Informative References [INTERAS-TE-REQ] Zhang and Vasseur, "MPLS Inter-AS Traffic Engineering Requirements", RFC4216, November 2005. [PER-DOMAIN] Ayyangar, A., Vasseur, J., and Zhang, R., "A Per-domain path computation method for establishing Inter-domain", draft-ietf-ccamp-inter-domain-pd-path-comp-03 (work in progress), August, 2006. [BRPC] JP. Vasseur, Ed., R. Zhang, N. Bitar, JL. Le Roux, "A Backward Recursive PCE-based Computation (BRPC) procedure to compute shortest inter-domain Traffic Engineering Label Switched Paths ", draft-ietf-pce-brpc-03.txt, Work in Progress, January 2007. Mach & Renhai Expires July 30, 2007 [Page 7] Internet-Draft Inter-AS Links connection information January 2007 Author's Addresses Mach Chen Huawei Technologies Co.,Ltd KuiKe Building, No.9 Xinxi Rd., Hai-Dian District Beijing, 100085 P.R. China Email: mach@huawei.com Renhai Zhang Huawei Technologies Co.,Ltd KuiKe Building, No.9 Xinxi Rd., Hai-Dian District Beijing, 100085 P.R. China Email: zhangrenhai@huawei.com 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 this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Mach & Renhai Expires July 30, 2007 [Page 8] Internet-Draft Inter-AS Links connection information January 2007 Disclaimer of Validity 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. 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Mach & Renhai Expires July 30, 2007 [Page 9]