--- 1/draft-ietf-mpls-crldp-unnum-09.txt 2006-02-05 00:37:49.000000000 +0100 +++ 2/draft-ietf-mpls-crldp-unnum-10.txt 2006-02-05 00:37:49.000000000 +0100 @@ -1,21 +1,21 @@ Network Working Group Kireeti Kompella Internet Draft Juniper Networks -Expiration Date: April 2003 Yakov Rekhter +Expiration Date: June 2003 Yakov Rekhter Juniper Networks Alan Kullberg NetPlane Systems Signalling Unnumbered Links in CR-LDP - draft-ietf-mpls-crldp-unnum-09.txt + draft-ietf-mpls-crldp-unnum-10.txt 1. Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. @@ -58,45 +58,52 @@ unnumbered links because the current signalling doesn't provide a way to indicate an unnumbered link in its Explicit Route Objects. This document proposes simple procedures and extensions that allow CR-LDP signalling [CR-LDP] to be used with unnumbered links. 5. Link Identifiers An unnumbered link has to be a point-to-point link. An LSR at each end of an unnumbered link assigns an identifier to that link. This identifier is a non-zero 32-bit number that is unique within the - scope of the LSR that assigns it. The IS-IS and/or OSPF and RSVP - modules on an LSR must agree on the identifiers. + scope of the LSR that assigns it. If one is using OSPF or ISIS as the + IGP in support of traffic engineering, then the IS-IS and/or OSPF and + CR-LDP modules on an LSR must agree on the identifiers. There is no a priori relationship between the identifiers assigned to a link by the LSRs at each end of that link. LSRs at the two end points of an unnumbered link exchange with each other the identifiers they assign to the link. Exchanging the identifiers may be accomplished by configuration, by means of a - protocol such as LMP ([LMP]), by means of RSVP/CR-LDP (especially in - the case where a link is a Forwarding Adjacency, see below), or by - means of IS-IS or OSPF extensions ([ISIS-GMPLS], [OSPF-GMPLS]). + protocol such as LMP ([LMP]), by means of CR-LDP (especially in the + case where a link is a Forwarding Adjacency, see below), or by means + of IS-IS or OSPF extensions ([ISIS-GMPLS], [OSPF-GMPLS]). Consider an (unnumbered) link between LSRs A and B. LSR A chooses an idenfitier for that link. So is LSR B. From A's perspective we refer to the identifier that A assigned to the link as the "link local identifier" (or just "local identifier"), and to the identifier that B assigned to the link as the "link remote identifier" (or just "remote identifier"). Likewise, from B's perspective the identifier that B assigned to the link is the local identifier, and the identifier that A assigned to the link is the remote identifier. - In the context of this document the term "Router ID" refers to the - "Router Address" as defined in [OSPF-TE], or "Traffic Engineering - Router ID" as defined in [ISIS-TE]. + In the context of this document the term "Router ID" means a stable + IP address of an LSR that is always reachable if there is any + connectivity to the LSR. This is typically implemented as a "loopback + address"; the key attribute is that the address does not become + unusable if an interface on the LSR is down. In some case this value + will need to be configured. If one is using OSPF or ISIS as the IGP + in support of traffic engineering, then it is RECOMMENDED to set the + Router ID to the "Router Address" as defined in [OSPF-TE], or + "Traffic Engineering Router ID" as defined in [ISIS-TE]. This section is equally applicable to the case of unnumbered component links (see [LINK-BUNDLE]). 6. Unnumbered Forwarding Adjacencies If an LSR that originates an LSP advertises this LSP as an unnumbered Forwarding Adjacency in IS-IS or OSPF (see [LSP-HIER]), or the LSR uses the Forwarding Adjacency formed by this LSP as an unnumbered component link of a bundled link (see [LINK-BUNDLE]), the LSR MUST @@ -124,22 +131,22 @@ Interface ID field of the Reverse Interface ID TLV (for the definition of Reverse Interface ID TLV see below). The LSR that is a tail-end of that Forwarding Adjacency sets the link local identifier for that link to the value that the LSR allocates to that Forwarding Adjacency, and the link remote identifier to the value carried in the Interface ID field of the Forward Interface ID TLV (for the definition of Forward Interface ID see below). 6.1. LSP_TUNNEL_INTERFACE_ID TLV - The LSP_TUNNEL_INTERFACE ID TLV has Type to be determined by IETF - consensus and length 8. The format is given below. + The LSP_TUNNEL_INTERFACE ID TLV has Type to be assigned by IANA and + length 8. The format is given below. Figure 1: LSP_TUNNEL_INTERFACE_ID TLV 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|0| Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSR's Router ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ @@ -150,41 +157,40 @@ MAPPING message. In the former case, we call it the "Forward Interface ID" for that LSP; in the latter case, we call it the "Reverse Interface ID" for the LSP. 7. Signalling Unnumbered Links in Explicit Route TLV A new Type of ER-Hop TLV of the Explicit Route TLV is used to specify unnumbered links. This Type is called Unnumbered Interface ID, and has the following format: + The Type is assigned by IANA, and the Length is 12. The L bit is set + to indicate a loose hop, and cleared to indicate a strict hop. + + The Interface ID is the identifier assigned to the link by the LSR + specified by the router ID. + Figure 2: Unnumbered Interface ID 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |0|0| Type = 0x0805 | Length = 12 | + |0|0| Type | Length = 12 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |L| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Router ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface ID (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - The Type is 0x0805 (Unnumbered Interface ID) and the Length is 12. - The L bit is set to indicate a loose hop, and cleared to indicate a - strict hop. - - The Interface ID is the identifier assigned to the link by the LSR - specified by the router ID. - 7.1. Processing the IF_ID TLV When an LSR receives a REQUEST message containing the IF_ID TLV (see [GMPLS-CRLDP]) with the IF_INDEX TLV, the LSR processes this TLV as follows. The LSR must have information about the identifiers assigned by its neighbors to the unnumbered links between the neighbors and the LSR. The LSR uses this information to find a link with tuple matching the tuple carried in the IF_INDEX TLV. If the matching tuple is found, the match identifies the link for which the LSR has to perform @@ -209,32 +215,27 @@ As part of the Explicit Route TLV processing, or to be more precise, as part of the next hop selection, if the outgoing link is unnumbered, the REQUEST message that the node sends to the next hop MUST include the IF_ID TLV, with the IP address field of that TLV set to the Router ID of the node, and the Interface ID field of that TLV set to the identifier assigned to the link by the node. 8. IANA Considerations RFC3036 [LDP] defines the LDP TLV name space. RFC3212 [CD-LDP] - further subdivides the range of RFC 3036 from that TLV space for TLVs - associated with the CR-LDP in the range 0x0800 - 0x08FF. - - Following the policies outlined in [IANA], TLV types in this range - are allocated through an IETF Consensus action. - - This document makes the following assignments: - - TLV Type - -------------------------------------- ---------- - UNNUMBERED_INTERFACE_ID 0x0805 - LSP_TUNNEL_INTERFACE_ID 0x08?? + further subdivides the range of that TLV space for TLVs associated + with the CR-LDP in the range 0x0800 - 0x08FF, and defines the rules + for the assignment of TLVs within that range using the terminology of + BCP 26 "Guidelines for Writing an IANA Considerations Section in + RFCs". Those rules apply to the assignment of TLV Types for the + Unnumbered Interface ID and LSP_TUNNEL_INTERFACE_ID TLVs defined in + this document. 9. Security Considerations This document extends CR-LDP and raises no new security issues. CR- LDP inherits the same security mechanism described in Section 4.0 of [LDP] to protect against the introduction of spoofed TCP segments into LDP session connection streams. 10. Acknowledgments