Networking Working Group R. Bradford Internet-Draft JP. Vasseur Intended Status: Standards Track Cisco Systems, Inc. Created:
March 27,May 14, 2008 A. Farrel Expires: September 27,November 14, 2008 Old Dog Consulting RSVP Extensions for Path Key Support draft-ietf-ccamp-path-key-ero-00.txtdraft-ietf-ccamp-path-key-ero-01.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. Abstract Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE) Label Switched Paths (LSPs) may be computed by Path Computation Elements (PCEs). Where the TE LSP crosses multiple domains, such as Autonomous Systems (ASes), the path may be computed by multiple PCEs that cooperate, with each responsible for computing a segment of the path. To preserve confidentiality of topology withwithin each AS, the PCE supports a mechanism to hide the contents of a segment of a path, called the Confidential Path Segment (CPS), by encoding the contents as a Path Key Subobject (PKS). This document describes the addition of this informationhow to carry Path Key Subobjects in the Resource Reservation Protocol (RSVP) signaling by inclusion in theExplicit Route Object (ERO)Objects (EROs) and Record Route Object (RRO).(RROs) so facilitate confiedntiality in the signaling of inter-domain TE LSPs. 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 [RFC2119]. 1. Introduction Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE) Label Switched Paths (LSPs) are signaled using the TE extensions to the Resource Reservation Protocol (RSVP-TE) [RFC3209], [RFC3473]. The routes followed by MPLS and GMPLS TE LSPs may be computed by Path Computation Elements (PCEs) [RFC4655]. Where the TE LSP crosses multiple domains,domains [RFC4726], such as Autonomous Systems (ASes), the path may be computed by multiple PCEs that cooperate, with each responsible for computing a segment of the path. To preserve confidentiality of topology with each AS, the PCE Communications Protocol (PCEP) [PCEP] supports a mechanism to hide the contents of a segment of a path, called the Confidential Path Segment (CPS), by encoding the contents as a Path Key Subobject (PKS) [PCE-PKS]. This document defines RSVP-TE protocol extensions necessary to support the use of Path Key Segments in MPLS and GMPLS signaling. 1.1. Usage Scenario Figure 1 shows a simple network constructed of two ASes. An LSP is desired from the Ingress in Domain-1 to the Egress in Domain-2. As described in [RFC4655], the Ingress Label Switching Router (LSR) acts as a Path Computation Client (PCC) and sends a request to its PCE (PCE-1). PCE-1 can compute the path within Domain-1, but has no visiblity into Domain-2. So PCE-1 cooperates with PCE-2 to complete the path computation. However, PCE-2 does not want to share the information about the path across Domain-2 with nodes outside the domain. So, as described in [PCE-PKS], PCE-2 reports the Domain-2 path segment using a Path Key Subobject rather than the details of the path. PCE-1 can now return the path to be signaled to the Ingress LSR in a path computation response with the Domain-2 segment still hidden as a Path Key Segment. In order to set up the LSP, the Ingress LSR signals using RSVP-TE and encodes the path reported by PCE-1 in the Explicit Route Object (ERO). This process is as normal for RSVP-TE, but requires that the PKS is also included in the ERO using the mechanisms defined in this document. When the signaling message (the RSVP-TE Path message) reaches ASBR-2 it consults PCE-2 to 'decode' the PKS. (The information about which PCE to use to decode the PKS is encoded within the PKS.) The PKS is replaced in the ERO with the expanded information about the path. ----------------------------- ---------------------------- | Domain-1 | | Domain-2 | | | | | | ------- | | ------- | | | PCE-1 |<---------------+--+-->| PCE-2 | | | ------- | | ------- | | ^ | | ^ | | | | | | | | v | | v | | ------- ---- | | ---- | | | PCC | - - |ASBR| | | |ASBR| - - ------ | | |Ingress|--|A|--|B|--| 1 |-+--+-| 2 |--|C|--|D|--|Egress| | | ------- - - ----- | | ---- - - ------ | | | | | ----------------------------- ---------------------------- Figure 1 : A Simple network to demonstrate the use of the PKS 2. Terminology CPS: Confidential Path Segment. A segment of a path that contains nodes and links that the AS policy requires to not be disclosed outside the AS. PCE: Path Computation Element: an entity (component, application or network node) that is capable of computing a network path or route based on a network graph and applying computational constraints. PKS: Path Key Subobject. A subobject of an Explicit Route Object which encodes a CPS, so as to preserve confidentiality. 3. RSVP-TE Path Key Subobject The Path Key Subobject (PKS) may be carried in the Explicit Route Object (ERO) of a RSVP-TE Path message [RFC3209]. The PKS is a fixed-lengthfixed- length subobject containing a Path-Key and a PCE-ID. The Path Key is an identifier, or token used to represent the CPS within the context of the PCE identified by the PCE-ID. The PCE-ID identifies the PCE that can decode the Path Key using a reachable IPv4 or IPv6 address of the PCE. In most cases, the decoding PCE is also the PCE that computed the Path Key and the associated path. Because of the IPv4 and IPv6 variants, two subobjects are defined as follows. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |L| Type | Length | Path Key | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PCE ID (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ L The L bit SHOULD NOT be set, so that the subobject represents a strict hop in the explicit route. Type Subobject Type for a Path Key with 32-bit PCE ID as assigned by IANA. Length The Length contains the total length of the subobject in bytes, including the Type and Length fields. The Length is always 8. PCE ID A 32-bit identifier of the PCE that can decode this key. The identifier MUST be unique within the scope of the domain that the CPS crosses, and MUST be understood by the LSR that will act as PCC for the expansion of the PKS. The interpretation of the PCE-ID is subject to domain-local policy. It MAY be an IPv4 address of the PCE that is always reachable, and MAY be an address that is restricted to the domain in which the LSR that is called upon to expand the CPS lies. Other values that have no meaning outside the domain (for example, the Router ID of the PCE) MAY be used to increase security or confidentiality. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |L| Type | Length | Path Key | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PCE ID (16 bytes) | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ L As above. Type Subobject Type for a Path Key with 128-bit PCE ID as assigned by IANA. Length The Length contains the total length of the subobject in bytes, including the Type and Length fields. The Length is always 20. PCE ID A 128-bit identifier of the PCE that can decode this key. The identifier MUST be unique within the scope of the domain that the CPS crosses, and MUST be understood by the LSR that will act as PCC for the expansion of the PKS. The interpretation of the PCE-ID is subject to domain-local policy. It MAY be an IPv6 address of the PCE that is always reachable, but MAY be an address that is restricted to the domain in which the LSR that is called upon to expand the CPS lies. Other values that have no meaning outside the domain (for example, the IPv6 TE Router ID) MAY be used to increase security (see Section 5). Note: The twins of these sub-objects are carried in PCEP messages as defined in [PCE-PKS]. 3.1. Explicit Route Object Processing Rules This section to be completed in a future release. 3.2. Reporting Path Key Segments in Record Route Objects This section to be completed in a future release. 4. Security Considerations - Confidentiality of the CPS (can other network elements probe for expansion of path-keys, possibly at random?). - Authenticity of the path-key (resilience to alteration by intermediaries, resilience to fake expansion of path-keys). - Resilience from DNS attacks (insertion of spurious path-keys; flooding of bogus path-key expansion requests). Most of the interactions required by this extension are point to point, can be authenticated and made secure as described in [PCEP] and [RFC3209]. These interactions are listed in [PCE-PKS] Thus, the major security issues can be dealt with using standard techniques for securing and authenticating point-to-point communications. In addition, it is recommended that the PCE providing a decode response should check that the LSR that issued the decode request is the head end of the decoded ERO segment. Further protection can be provided by using a PCE ID to identify the decoding PCE that is only meaningful within the domain that contains the LSR at the head of the CPS. This may be an IP address that is only reachable from within the domain, or some not-address value. The former requires configuration of policy on the PCEs, the latter requires domain-wide policy. 5. Manageability Considerations 5.1. Control of Function Through Configuration and Policy The treatment of a path segment as a CPS, and its substitution in a PCReq ERO with a PKS, is a function that SHOULD be under operator and policy control where a PCE supports the function. The operator SHOULD be given the ability to specify which path segments are to be replaced and under what circumstances. For example, an operator might set a policy that states that every path segment for the operator's domain will be replaced by a PKS when the PCReq has been issued from outside the domain. 6. IANA considerations The IANA section will be detailed in further revision of this document. It will include code point requests for the three new ERO sub- objects, and a new ErrorSpec Error Code. Note: The twins of these sub-objects are be carried in PCEP messages as defined in [PCE-PKS]. Ideally, IANA assignment of the subobject types will be identical. 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. [PCEP] Vasseur, J.P., Le Roux, J.L., Ayyangar, A., Oki, E., Ikejiri, A., Atlas, A., Dolganow, A., "Path Computation Element (PCE) communication Protocol (PCEP)", draft-ietf-pce-pcep, work in progress. 7.2. Informational References[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. [RFC3473] Berger, L., et al. "GMPLS Singlaling RSVP-TE extensions", RFC3473, January 2003. 7.2. Informational References [PCEP] Vasseur, J.P., Le Roux, J.L., Ayyangar, A., Oki, E., Ikejiri, A., Atlas, A., Dolganow, A., "Path Computation Element (PCE) communication Protocol (PCEP)", draft-ietf-pce-pcep, work in progress. [PCE-PKS] Bradford, R., Vasseur, J.P., and Farrel, A., "Preserving Topology Confidentiality in Inter-Domain Path Computation Using a Key-Based Mechanism", draft-ietf-pce-path-key, work in progress. [RFC4655] Farrel, A., Vasseur, J.P., and Ash, J., "Path Computation Element (PCE) Architecture", RFC 4655, August 2006. [RFC4726] Farrel, A., Vasseur, J.P., and Ayyangar, A., "A Framework for Inter-Domain Multiprotocol Label Switching Traffic Engineering", RFC 4726, November 2006. 8. Authors' Addresses: Rich Bradford Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough, MA - 01719 USA Email: email@example.com J.-P Vasseur Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough, MA - 01719 USA Email: firstname.lastname@example.org Adrian Farrel Old Dog Consulting EMail: email@example.com Full Copyright Statement Copyright (C) The IETF Trust (2008). 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. 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