Advertising a Router's Local Addresses in OSPF Traffic Engineering (TE) Extensions
The information below is for an old version of the document that is already published as an RFC.
This is an older version of an Internet-Draft that was ultimately published as RFC 5786.
|Authors||Rahul Aggarwal , Kireeti Kompella|
|Last updated||2018-12-20 (Latest revision 2009-12-02)|
|RFC stream||Internet Engineering Task Force (IETF)|
|Additional resources||Mailing list discussion|
|IESG||IESG state||RFC 5786 (Proposed Standard)|
|Responsible AD||Ross Callon|
|Send notices to||(None)|
Network Working Group R. Aggarwal Internet Draft Juniper Networks Expiration Date: June 2010 K. Kompella Juniper Networks December 02, 2009 Advertising a Router's Local Addresses in OSPF TE Extensions draft-ietf-ospf-te-node-addr-07.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. Copyright and License 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. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this Raggarwa & Kompella [Page 1] Internet Draft draft-ietf-ospf-te-node-addr-07.txt December 2009 material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Abstract OSPF Traffic Engineering (TE) extensions are used to advertise TE Link State Advertisements (LSAs) containing information about TE- enabled links. The only addresses belonging to a router that are advertised in TE LSAs are the local addresses corresponding to TE- enabled links, and the local address corresponding to the Router ID. In order to allow other routers in a network to compute Multiprotocol Label Switching (MPLS) traffic engineered Label Switched Paths (TE LSPs) to a given router's local addresses, those addresses must also be advertised by OSPF TE. This document describes procedures that enhance OSPF TE to advertise a router's local addresses. Raggarwa & Kompella [Page 2] Internet Draft draft-ietf-ospf-te-node-addr-07.txt December 2009 Table of Contents 1 Specification of requirements ......................... 3 2 Introduction .......................................... 3 2.1 Motivation ............................................ 3 3 Rejected Potential Solution ........................... 4 4 Solution .............................................. 4 4.1 Node Attribute TLV .................................... 5 4.2 Operation ............................................. 6 5 Security Considerations ............................... 7 6 IANA Considerations ................................... 7 7 Acknowledgements ...................................... 7 8 References ............................................ 8 8.1 Normative References .................................. 8 8.2 Informative References ................................ 8 9 Authors' Addresses .................................... 8 1. Specification of requirements 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 [RFC2119]. 2. Introduction 2.1. Motivation In some cases it is desirable to set up constrained shortest path first (CSPF) computed Multiprotocol Label Switching (MPLS) Traffic Engineered Label Switched Paths (TE LSPs) to local addresses of a router, that are not currently advertised in the TE LSAs i.e., loopback and non-TE interface addresses. For instance, in a network carrying VPN and non-VPN traffic, it is often desirable to use different MPLS TE LSPs for the VPN traffic and the non-VPN traffic. In this case one loopback address may be used as the BGP next-hop for VPN traffic while another may be used as the BGP next-hop for non-VPN traffic. It is also possible that different BGP sessions are used for VPN and non-VPN services. Hence two separate Raggarwa & Kompella [Page 3] Internet Draft draft-ietf-ospf-te-node-addr-07.txt December 2009 MPLS TE LSPs are desirable, one to each loopback address. However, current routers in an OSPF network can only use CSPF to compute MPLS TE LSPs to the router ID or the local addresses of a remote router's TE enabled links. This restriction arises because OSPF TE extensions [RFC3630, RFC5329] only advertise the router ID and the local addresses of TE enabled links of a given router. Other routers in the network can populate their traffic engineering database (TED) with these local addresses belonging to the advertising router. However, they cannot populate the TED with the advertising router's other local addresses, i.e., loopback and non-TE interface addresses. OSPFv2 stub links in the router LSA [RFC2328], provide stub reachability information to the router but are not sufficient to learn all the local addresses of a router. In particular for a subnetted point-to-point (P2P) interface the stub link ID is the subnet address. While for a non-subnetted interface the stub link ID is the neighbor address. Intra-prefix LSAs in OSPFv3 [RFC5340] are also not sufficient to learn the local addresses. For the above reasons this document defines an enhancement to OSPF TE extensions to advertise the local addresses of a node. 3. Rejected Potential Solution A potential solution would be to advertise a TE link TLV for each local address, possibly with a new link type. However, this is inefficient since the only meaningful information is the address. Furthermore, this would require implementations to process these TE link TLVs differently from others; for example, the TE metric is normally considered a mandatory sub-TLV, but would have no meaning for a local address. 4. Solution The solution is to advertise the local addresses of a router in a new OSPF TE LSA node attribute TLV. It is anticipated that the node attribute TLV will also prove more generally useful. Raggarwa & Kompella [Page 4] Internet Draft draft-ietf-ospf-te-node-addr-07.txt December 2009 4.1. Node Attribute TLV The node attribute TLV carries the attributes associated with a router. The TLV type is TBD and the length is variable. It contains one or more sub-TLVs. This document defines the following sub-TLVs: 1. Node IPv4 Local Address sub-TLV 2. Node IPv6 Local Address sub-TLV The node IPv4 local address sub-TLV has a type of 1 and contains one or more local IPv4 addresses. It has the following format: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Len 1 | IPv4 Prefix 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Prefix 1 cont. | : +-+-+-+-+-+-+-+-+ ~ : . : ~ . +-+-+-+-+-+-+-+-+ : . | Prefix Len n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Prefix n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Each local IPv4 address is encoded as a <Prefix Length, Prefix> tuple. Prefix Length is encoded in 1 byte. It is the number of bits in the Address and can be at most 32. Prefix is an IPv4 address prefix and is encoded in 4 bytes with zero bits as necessary. The Node IPv4 Local Address sub-TLV length is in octets. It is the sum of the lengths of all n IPv4 Address encodings in the sub-TLV where n is the number of local addresses included in the sub-TLV. The node IPv6 local address sub-TLV has a type of 2 and contains one or more local IPv6 addresses. It has the following format: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 2 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Len 1 | Prefix 1 Opt. | IPv6 Prefix 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Prefix 1 cont. : Raggarwa & Kompella [Page 5] Internet Draft draft-ietf-ospf-te-node-addr-07.txt December 2009 : . ~ ~ . : . : +-+-+-+-+-++-+-+-+-+-++-+-+-+-+-+ : | Prefix Len n | Prefix n Opt. | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Prefix n : | : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-- Each local IPv6 address is encoded using the procedures in [RFC5340]. Each IPv6 address MUST be represented by a combination of three fields: PrefixLength, PrefixOptions, and Address Prefix. PrefixLength is the length in bits of the prefix and is an 8 bit field. PrefixOptions is an 8-bit field describing various capabilities associated with the prefix [RFC5340]. Address Prefix is an encoding of the prefix itself as an even multiple of 32-bit words, padding with zero bits as necessary. This encoding consumes (PrefixLength + 31) / 32) 32-bit words. The Node IPv6 Local Address sub-TLV length is in octets. It is the sum of the lengths of all n IPv6 Address encodings in the sub-TLV where n is the number of local addresses included in the sub-TLV. 4.2. Operation A router announces one or more local addresses in the node attribute TLV. The local addresses that can be learned from TE LSAs i.e., router address and TE interface addresses SHOULD NOT be advertised in the node local address sub-TLV. The local addresses advertised will depend on the local configuration of the advertising router. The default behavior MAY be to advertise all the loopback interface addresses. The node attribute TLV MUST NOT appear in more than one TE LSA originated by a router. Furthermore, such a LSA MUST NOT include more than one node attribute TLV. A node attribute TLV MUST NOT carry more than one Node IPv4 Local Address sub-TLV. A node attribute TLV MUST NOT carry more than one Node IPv6 Local Address sub-TLV. Raggarwa & Kompella [Page 6] Internet Draft draft-ietf-ospf-te-node-addr-07.txt December 2009 5. Security Considerations This document does not introduce any further security issues other than those discussed in [RFC3630, RFC5329]. 6. IANA Considerations The Node Attribute TLV type has to be IANA assigned from the range 3 - 32767 as specified in [RFC3630], from the top level types in TE LSAs registry maintained by IANA at [IANA-OSPF-TE]. IANA is requested to maintain the registry for the sub-TLVs of the node attribute TLV and reserve value 1 for Node IPv4 Local Address sub-TLV and value 2 for Node IPv6 Local Address sub-TLV. The guidelines for the assignment of types for sub-TLVs of the node attribute TLV are as follows: o Types in the range 3-32767 are to be assigned via Standards Action. o Types in the range 32768-32777 are for experimental use; these will not be registered with IANA, and MUST NOT be mentioned by RFCs. o Types in the range 32778-65535 are not to be assigned at this time. Before any assignments can be made in this range, there MUST be a Standards Track RFC that specifies IANA Considerations that covers the range being assigned. 7. Acknowledgements We would like to thank Nischal Sheth for his contribution to this work. We would also like to thank Jean Philippe Vasseur, Acee Lindem, Venkata Naidu, Dimitri Papadimitriou and Adrian Farrel for their comments. Raggarwa & Kompella [Page 7] Internet Draft draft-ietf-ospf-te-node-addr-07.txt December 2009 8. References 8.1. Normative References [RFC2328] Moy, J., "OSPF Version 2", RFC 2328, April 1998. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3630] D. Katz, K. Kompella, D. Yeung, "Traffic Engineering Extensions to OSPF version 2", RFC 3630, September 2003. [RFC5340] R. Coltun, et. al.,"OSPF for IPv6", RFC 5340. 8.2. Informative References [RFC5329] K. Ishiguro, T. Takada, "Traffic Engineering Extensions to OSPF version 3", RFC 5329 [IANA-OSPF-TE] http://www.iana.org/assignments/ospf-traffic-eng-tlvs 9. Authors' Addresses Rahul Aggarwal Juniper Networks 1194 North Mathilda Ave. Sunnyvale, CA 94089 Phone: +1-408-936-2720 Email: firstname.lastname@example.org Kireeti Kompella Juniper Networks 1194 North Mathilda Ave. Sunnyvale, CA 94089 Email: email@example.com Raggarwa & Kompella [Page 8] Internet Draft draft-ietf-ospf-te-node-addr-07.txt December 2009 Raggarwa & Kompella [Page 9]