Internet Engineering Task Force (IETF) L. Berger Request for Comments: 6780 LabN Updates: 2205, 3209, 3473, 4872 F. Le Faucheur Category: Standards Track A. Narayanan ISSN: 2070-1721 Cisco October 2012 RSVP ASSOCIATION Object Extensions Abstract The RSVP ASSOCIATION object was defined in the context of GMPLS- controlled Label Switched Paths (LSPs). In this context, the object is used to associate recovery LSPs with the LSP they are protecting. This object also has broader applicability as a mechanism to associate RSVP state. This document defines how the ASSOCIATION object can be more generally applied. This document also defines Extended ASSOCIATION objects that, in particular, can be used in the context of the MPLS Transport Profile (MPLS-TP). This document updates RFC 2205, RFC 3209, and RFC 3473. It also generalizes the definition of the Association ID field defined in RFC 4872. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6780. Berger, et al. Standards Track [Page 1] RFC 6780 RSVP Extensions October 2012 Copyright Notice Copyright (c) 2012 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. Table of Contents 1. Introduction ....................................................2 1.1. Conventions Used in This Document ..........................4 2. Generalized Association ID Field Definition .....................4 3. Non-GMPLS and Non-Recovery Usage ................................4 3.1. Upstream Initiated Association .............................5 3.1.1. Path Message Format .................................5 3.1.2. Path Message Processing .............................6 3.2. Downstream Initiated Association ...........................7 3.2.1. Resv Message Format .................................8 3.2.2. Resv Message Processing .............................8 3.3. Association Types ..........................................9 3.3.1. Resource Sharing Association Type ...................9 3.3.2. Unknown Association Types ..........................10 4. IPv4 and IPv6 Extended ASSOCIATION Objects .....................10 4.1. IPv4 and IPv6 Extended ASSOCIATION Object Format ..........11 4.2. Processing ................................................13 5. Compatibility ..................................................14 6. Security Considerations ........................................14 7. IANA Considerations ............................................15 7.1. IPv4 and IPv6 Extended ASSOCIATION Objects ................15 7.2. Resource Sharing Association Type .........................15 8. Acknowledgments ................................................16 9. References .....................................................16 9.1. Normative References ......................................16 9.2. Informative References ....................................16 Berger, et al. Standards Track [Page 2] RFC 6780 RSVP Extensions October 2012 1. Introduction End-to-end and segment recovery are defined for GMPLS-controlled Label Switched Paths (LSPs) in [RFC4872] and [RFC4873], respectively. Both definitions use the ASSOCIATION object to associate recovery LSPs with the LSP they are protecting. Additional narrative on how such associations are to be identified is provided in [RFC6689]. This document expands the possible usage of the ASSOCIATION object to non-GMPLS and non-recovery contexts. The expanded usage applies equally to GMPLS LSPs [RFC3473], MPLS LSPs [RFC3209], and non-LSP RSVP sessions [RFC2205] [RFC2207] [RFC3175] [RFC4860]. This document also reviews how associations should be made in the case in which the object is carried in a Path message; additionally, it defines usage with Resv messages. This section also discusses usage of the ASSOCIATION object outside the context of GMPLS LSPs. Some examples of non-LSP association being used to enable resource sharing are: o Voice Call-Waiting: A bidirectional voice call between two endpoints, A and B, is signaled using two separate unidirectional RSVP reservations for the flows A->B and B->A. If endpoint A wishes to put the A-B call on hold and join a separate A-C call, it is desirable that network resources on common links be shared between the A-B and A-C calls. The B->A and C->A subflows of the call can share resources using existing RSVP sharing mechanisms, but only if they use the same destination IP addresses and ports. Since by definition, the RSVP reservations for the subflows A->B and A->C of the call must have different IP addresses in the SESSION objects, this document defines a new mechanism to associate the subflows and allow them to share resources. o Voice Shared Line: A voice shared line is a single number that rings multiple endpoints (which may be geographically diverse), such as phone lines to a manager's desk and to their assistant. A Voice over IP (VoIP) system that models these calls as multiple point-to-point unicast pre-ring reservations would result in significantly over- counting bandwidth on shared links, since RSVP unicast reservations to different endpoints cannot share bandwidth. So, a new mechanism is defined in this document to allow separate unicast reservations to be associated and to share resources. Berger, et al. Standards Track [Page 3] RFC 6780 RSVP Extensions October 2012 o Symmetric NAT: RSVP permits sharing of resources between multiple flows addressed to the same destination D, even from different senders S1 and S2. However, if D is behind a NAT operating in symmetric mode [RFC5389], it is possible that the destination port of the flows S1->D and S2->D may be different outside the NAT. In this case, these flows cannot share resources using RSVP, since the SESSION objects for these two flows outside the NAT have different destination ports. This document defines a new mechanism to associate these flows and allow them to share resources. In order to support the wider usage of the ASSOCIATION object, this document generalizes the definition of the Association ID field defined in RFC 4872. This generalization has no impact on existing implementations. When using the procedures defined below, association is identified based on exact ASSOCIATION object matching. Some of the other matching mechanisms defined in RFC 4872, e.g., matching based on Session IDs, are not generalized. This document allows for, but does not specify, association type-specific processing. This document also defines the Extended ASSOCIATION objects that can be used in the context of MPLS-TP. The scope of the Extended ASSOCIATION objects is not limited to MPLS-TP. 1.1. 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 [RFC2119]. 2. Generalized Association ID Field Definition The Association ID field is carried in the IPv4 and IPv6 ASSOCIATION objects defined in [RFC4872]. The [RFC4872] definition of the field reads: A value assigned by the LSP head-end. When combined with the Association Type and Association Source, this value uniquely identifies an association. This document allows for the origination of ASSOCIATION objects by nodes other than "the LSP head-end". As such, the definition of the Association ID field needs to be generalized to accommodate such usage. This document defines the Association ID field of the IPv4 and IPv6 ASSOCIATION objects as: Berger, et al. Standards Track [Page 4] RFC 6780 RSVP Extensions October 2012 A value assigned by the node that originated the association. When combined with the other fields carried in the object, this value uniquely identifies an association. This change in definition does not impact the procedures or mechanisms defined in [RFC4872] or [RFC4873], nor does it impact the existing implementations of [RFC4872] or [RFC4873]. 3. Non-GMPLS and Non-Recovery Usage While the ASSOCIATION object [RFC4872] is defined in the context of GMPLS recovery, the object can have wider application. [RFC4872] defines the object to be used to "associate LSPs with each other", and then defines an Association Type field to identify the type of association being identified. It also specifies that the Association Type field is to be considered when determining association, i.e., there may be type-specific association rules. As defined by [RFC4872] and reviewed in [RFC6689], this is the case for recovery type ASSOCIATION objects. [RFC6689], notably the text related to resource sharing types, can also be used as the foundation for a generic method for associating LSPs when there is no type-specific association defined. The remainder of this section defines the general rules to be followed when processing ASSOCIATION objects. Object usage in both Path and Resv messages is discussed. The usage applies equally to GMPLS LSPs [RFC3473], MPLS LSPs [RFC3209], and non-LSP RSVP sessions [RFC2205] [RFC2207] [RFC3175] [RFC4860]. As described below, association is always done based on matching either Path state to Path state, or Resv state to Resv state, but not Path state to Resv State. This section applies to the ASSOCIATION objects defined in [RFC4872]. 3.1. Upstream-Initiated Association Upstream-initiated association is represented in ASSOCIATION objects carried in Path messages and can be used to associate RSVP Path state across MPLS Tunnels / RSVP sessions. (Note, per [RFC3209], an MPLS tunnel is represented by an RSVP SESSION object, and multiple LSPs may be represented within a single tunnel.) Cross-LSP association based on Path state is defined in [RFC4872]. This section extends that definition by specifying generic association rules and usage for non-LSP uses. This section does not modify processing required to support [RFC4872] and [RFC4873], which is reviewed in Section 3 of [RFC6689]. The use of an ASSOCIATION object in a single session is not precluded. Berger, et al. Standards Track [Page 5] RFC 6780 RSVP Extensions October 2012 3.1.1. Path Message Format This section provides the Backus-Naur Form (BNF), see [RFC5511], for Path messages containing ASSOCIATION objects. BNF is provided for both MPLS and for non-LSP session usage. Unmodified RSVP message formats and some optional objects are not listed. The formats for MPLS and GMPLS sessions are unmodified from [RFC4872] and can be represented based on the BNF in [RFC3209] as: ::= [ ] [ ] [ ] [ ... ] [ ... ] The format for non-LSP sessions as based on the BNF in [RFC2205] is: ::= [ ] [ ... ] [ ... ] [ ] In general, relative ordering of ASSOCIATION objects with respect to each other, as well as with respect to other objects, is not significant. Relative ordering of ASSOCIATION objects of the same type SHOULD be preserved by transit nodes. 3.1.2. Path Message Processing This section is based on, and extends, the processing rules described in [RFC4872] and [RFC4873], which is reviewed in [RFC6689]. This section applies equally to GMPLS LSPs, MPLS LSPs, and non-LSP session state. Note, as previously stated, this section does not modify processing required to support [RFC4872] and [RFC4873]. A node sending a Path message chooses when an ASSOCIATION object is to be included in the outgoing Path message. To indicate association between multiple sessions, an appropriate ASSOCIATION object MUST be included in the outgoing Path messages corresponding to each of the associated sessions. In the absence of Association-Type-specific rules for identifying association, the included ASSOCIATION object Berger, et al. Standards Track [Page 6] RFC 6780 RSVP Extensions October 2012 MUST be identical. When there is an Association-Type-specific definition of association rules, the definition SHOULD allow for association based on identical ASSOCIATION objects. This document does not define any Association-Type-specific rules. (See Section 3 of [RFC6689] for a review of Association-Type-specific rules derived from [RFC4872].) When creating an ASSOCIATION object, the originator MUST format the object as defined in Section 16.1 of [RFC4872]. The originator MUST set the Association Type field based on the type of association being identified. The Association ID field MUST be set to a value that uniquely identifies the specific association within the context of the Association Source field. The Association Source field MUST be set to a unique address assigned to the node originating the association. A downstream node can identify an upstream-initiated association by performing the following checks. When a node receives a Path message, it MUST check each ASSOCIATION object received in the Path message to determine if the object contains an Association Type field value supported by the node. For each ASSOCIATION object containing a supported association type, the node MUST then check to see if the object matches an ASSOCIATION object received in any other Path message. To perform this matching, a node MUST examine the Path state of all other sessions and compare the fields contained in the newly received ASSOCIATION object with the fields contained in the Path state's ASSOCIATION objects. An association is deemed to exist when the same values are carried in all fields of the ASSOCIATION objects being compared. Type-specific processing of ASSOCIATION objects is outside the scope of this document. Note that as more than one association may exist, the described matching MUST continue after a match is identified and MUST be performed against all local Path state. It is also possible for there to be no match identified. Unless there are type-specific processing rules, downstream nodes MUST forward all ASSOCIATION objects received in a Path message in any corresponding outgoing Path messages without modification. This processing MUST be followed for unknown Association Type field values. 3.2. Downstream-Initiated Association Downstream-initiated association is represented in ASSOCIATION objects carried in Resv messages and can be used to associate RSVP Resv state across MPLS Tunnels/RSVP sessions. Cross-LSP association, based on Path state, is defined in [RFC4872]. This section defines Berger, et al. Standards Track [Page 7] RFC 6780 RSVP Extensions October 2012 cross-session association based on Resv state. This section places no additional requirements on implementations supporting [RFC4872] and [RFC4873]. Note, the use of an ASSOCIATION object in a single session is not precluded. 3.2.1. Resv Message Format This section provides the Backus-Naur Form (BNF), see [RFC5511], for Resv messages containing ASSOCIATION objects. BNF is provided for both MPLS and for non-LSP session usage. Unmodified RSVP message formats and some optional objects are not listed. The formats for MPLS, GMPLS, and non-LSP sessions are identical and are represented based on the BNF in [RFC2205] and [RFC3209]: ::= [ ] [ ] [ ] [ ... ] [ ... ]