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     CCAMP Working Group                                       Zafar Ali
     Internet Draft                                       George Swallow
     Intended status: Standard Track                   Clarence Filsfils
     Expires: September 11, 2012                             Luyuan Fang
                                                           Cisco Systems
                                                          Ruediger Kunze
                                                     Deutsche Telekom AG
                                                          March 12, 2012
     
     
     
          Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)
          extension for signaling Objective Function and Metric Bound
           draft-ali-ccamp-rc-objective-function-metric-bound-01.txt
     
     
     Status of this Memo
     
     This Internet-Draft is submitted in full conformance with the
     provisions of BCP 78 and BCP 79.
     
     Internet-Drafts are working documents of the Internet Engineering
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     This Internet-Draft will expire on September 11, 2012.
     
     Copyright Notice
     
     
     Copyright (c) 2012 IETF Trust and the persons identified as the
     document authors.  All rights reserved.
     
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     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
     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
     
     When using GMPLS control plane, the ingress node may need to
     request remote node to perform route computation or expansion. In
     such cases, ingress node needs to convey the required objective
     function for the path computation algorithm to the remote node, so
     that the remote node can perform the route computation or
     expansion. Similarly, there are cases the ingress needs to indicate
     a TE metric bound for the loose segment which is expanded by the
     remote node(s). This document defines extensions to the RSVP-TE
     Protocol to allow an ingress node to request the required objective
     function for the path computation, as well as a metric bound to
     influence route computation decisions at a remote node(s).
     
     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].
     
     Table of Contents
     
     
     Copyright Notice..................................................1
     1. Introduction...................................................3
     2. RSVP-TE signaling extensions...................................4
           2.1. Objective Function (OF) Subobject......................4
              2.1.1. Minimum TE Metric Cost Path Objective Function....6
              2.1.2. Minimum IGP Metric Cost Path Objective Function...6
              2.1.3. Minimum Latency Path Objective Function...........6
              2.1.4. Minimum Latency Variation Path Objective Function.6
           2.2. Metric subobject.......................................7
           2.3. Processing Rules for the OF Subobjects.................8
           2.4. Processing Rules for the Metric subobject..............9
     
     
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     3. Security Considerations.......................................10
     4. IANA Considerations...........................................10
     5. Acknowledgments...............................................11
     6. References....................................................11
           6.1. Normative References..................................11
           6.2. Informative References................................11
     
     1. Introduction
     
       As noted in [OSPF-TE-METRIC] and [ISIS-TE-METRIC], in certain
       networks such as financial information networks (e.g. stock
       market data providers), network performance criteria (e.g.
       latency) are becoming as critical to data path selection as other
       metrics. In other words, such networks often require finding a
       path that is computed to minimize end-to-end latency. Even if
       paths are computed to minimize some other TE metric, it is often
       required to specify an acceptable latency bound as a constraint.
       In summary, there is a requirement to be able to find an end-to-
       end path with different optimization criteria and with
       performance bound(s) on the TE metric.
     
       When the entire route for an LSP is computed at the ingress node,
       the above-mentioned requirement can be met by a local decision at
       that node. However, there are scenarios where partial or full
       route computations are performed by remote nodes. The scenarios
       include (but are not limited to):
     
       .  LSPs with loose hops in the Explicit Route Object (ERO), e.g.
          inter-domain LSPs.
     
       .  Generalized Multi-Protocol Label Switching (GMPLS) User-
          Network Interface (UNI) where route computation may be
          performed by the UNI-Network (server) node [RFC 4208];
     
       In these scenarios, there is a need for the ingress node to
       convey TE metrics (e.g., IGP metric, TE metric, hop counts,
       latency, etc.) to be optimized by the path computation algorithm
       at the remote node performing route computation or expansion.
       Similarly, there is a need for the ingress node to indicate a TE
       metric bound for the loose segment being expanded by the remote
       node.
     
        [RFC5541] defines extensions to the Path Computation Element
        communication Protocol (PCEP) to allow a Path Computation Client
        (PCC) indicate in a path computation request the desired
        objective function. [RFC5440] defines extension to the PCEP to
        allow a PCC indicate in a path computation request a bound on
        given TE metric(s). This draft defines a similar mechanism to
     
     
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        the RSVP-TE protocol to allow an ingress node to indicate in a
        Path request the desired objective function at the loose hops.
        The objective function is used by the node performing route
        expansion to find the "best" candidate paths. The draft also
        defines a RSVP-TE protocol mechanism to allow an ingress node to
        indicate TE metric bound(s) associated with the route expansion
        request.
     
     2. RSVP-TE signaling extensions
     
        This section defines RSVP-TE signaling extensions required to
        address the above-mentioned requirements.  Two new ERO subobject
        types, Objective Function (OF) and Metric, are defined for this
        purpose. Their purpose is as follows.
     
       .  OF subobject conveys a set of one or more specific
          optimization criteria that MUST be followed in expanding route
          of a TE-LSP in MultiProtocol Label Switching (MPLS) and GMPLS
          networks.
     
       .  Metric subobject indicates the bound on the path metric that
          MUST NOT be exceeded for the loose segment to be considered as
          acceptable by the ingress node.
     
       The scope of the Metric and OF subobjects is the node performing
       the expansion for loose ERO and the subsequent ERO subobject that
       identifies an abstract node. The following subsection provides
       the details.
     
     2.1. Objective Function (OF) Subobject
     
        A new ERO subobject type Objective Function (OF) is defined in
        order for the ingress node to indicate the required objective
        function on a loose hop. The ERO subobject type OF is optional.
        It MAY be carried within an ERO object of RSVP-TE Path message.
        The OF subobject 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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |L|    Type     |     Length    |    OF Code    |   Reserved    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       //              Optional TLV(s)                                //
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     
        The fields of OF subobject are defined as follows:
     
     
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           L bit: The L bit SHOULD be set, so that the subobject
        represents a loose hop in the explicit route.
     
           Type: The Type is to be assigned by IANA (suggested value:
        66).
     
           Length: The Length contains the total length of the subobject
        in bytes, including the Type field, the Length field and the
        length of the optional TLV(s). When there is no optional TLV,
        the Length is 4.
     
           OF Code (1 byte): The identifier of the objective function.
        The following OF code values are suggested. These values are to
        be assigneyd by IANA.
     
           * OF code value 0 is reserved.
     
           * OF code value 1 (to be assigned by IANA) is for Minimum TE
        Metric Cost Path (MTMCP) OF defined in this document. See
        definition of MTCP OF in the following.
     
           * OF code value 2 (to be assigned by IANA) is for Minimum Interior
        Gateway Protocol (IGP) Metric Cost Path (MIMCP) OF defined in the
        following.
     
           * OF code value 3 (to be assigned by IANA) is for Minimum
        Load Path (MLP) OF as defined in RFC5541.
     
           * OF code value 4 (to be assigned by IANA) is for Maximum
        Residual Bandwidth Path (MBP) OF as defined in RFC5541.
     
           * OF code value 5 (to be assigned by IANA) is for Minimize
        Aggregate Bandwidth Consumption (MBC) OF as defined in RFC5541.
     
           * OF code value 6 (to be assigned by IANA) is for Minimize
        the Load of the most loaded Link (MLL) OF as defined in RFC5541.
     
           * OF code value 7 is skipped (to keep the objective function
        code values consistent between [RFC5541] and this draft.
     
           * OF code value 8 (to be assigned by IANA) is for Minimum
        Latency Path (MLP) OF defined in this document. See definition
        of MLP OF in the following.
     
           * OF code value 9 (to be assigned by IANA) is for Minimum
        Latency Variation Path (MLVP) OF defined in this document. See
        definition of MLVP OF in the following.
     
     
     
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        Other objective functions may be defined in future.
     
           Reserved (1 byte): This field MUST be set to zero on
        transmission and MUST be ignored on receipt.
     
           Optional TLVs may be defined in the future to encode
        objective function parameters.
     
     2.1.1. Minimum TE Metric Cost Path Objective Function
     
        Minimum TE Metric Cost Path (MTMCP) OF is defined as an
        Objective Function where a path is computed such that the sum of
        the TE metric of the links along the path is minimized. In the
        context of loose hop expansion, the ERO expanding node MUST try
        to find a route such that the sum of the TE metric of the links
        along the route is minimized.
     
     2.1.2. Minimum IGP Metric Cost Path Objective Function
     
        Minimum IGP Metric Cost Path (MIMCP) OF is defined as an
        Objective Function where a path is computed such that the sum of
        the IGP metric of the links along the path is minimized. In the
        context of loose hop expansion, the ERO expanding node MUST try
        to find a route such that the sum of the IGP metric of the links
        along the route is minimized.
     
     2.1.3. Minimum Latency Path Objective Function
     
        Minimum Latency Path (MLP) OF is defined as an Objective
        Function where a path is computed such that latency of the path
        is minimized. In the context of loose hop expansion, the ERO
        expanding node MUST try to find a route such that overall
        latency of the loose hop is minimized.
     
     2.1.4. Minimum Latency Variation Path Objective Function
     
        Minimum Latency Variation Path (MLVP) OF is defined as an
        Objective Function where a path is computed such that latency
        variation in the path is minimized. In the context of loose hop
        expansion, the ERO expanding node MUST try to find a route such
        that overall latency variation of the loose hop is minimized.
     
     
     
     
     
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     2.2. Metric subobject
     
        The ERO subobject type Metric is optional. It MAY be carried
        within an ERO object of RSVP-TE Path message. This subobject 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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |L|    Type     |     Length    | metric-type |     Reserved    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                          metric-bound                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     
        The fields of the Metric subobject are defined as follows:
     
           L bit: The L bit SHOULD be set, so that the subobject
          represents a loose hop in the explicit route.
     
           Type: The Type is to be assigned by IANA (suggested value:
          67).
     
           Length: The Length is 8.
     
           Metric-type (8 bits):  Specifies the metric type associated
           with the partial route expended by the node processing the
           loose ERO. The following values are currently defined:
     
                 *  T=1: cumulative IGP cost
     
                 *  T=2: cumulative TE cost
     
                 *  T=3: Hop Counts
     
                 *  T=4: Cumulative Latency
     
                 *  T=5: Cumulative Latency Variation
     
           Reserved:  This field MUST be set to zero on transmission and
        MUST be ignored on receipt.
     
           Metric-bound (32 bits):  The metric-bound indicates an upper
        bound for the path metric that MUST NOT be exceeded for the ERO
        expending node to consider the computed path as acceptable. The
        metric bound is encoded in 32 bits using IEEE floating point
        format as defined in [IEEE.754.1985]).
     
     
     
     
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     2.3. Processing Rules for the OF Subobjects
     
        The basic processing rules of an ERO are not altered. Please
        refer to [RFC3209] for details.
     
        The scope of the OF subobject is the previous ERO subobject that
        identifies an abstract node, and the subsequent ERO subobject
        that identifies an abstract node.  Multiple OF subobjects may be
        present between any pair of abstract nodes.
     
        The following conditions SHOULD result in Path Error with error
        code "Routing Problem" and error subcode "Bad EXPLICIT_ROUTE
        object":
     
       .  If the first OF subobject is not preceded by a subobject
          identifying the next hop.
       .  If the OF subobject follows a subobject that does not have
          the L-bit set.
     
       If the processing node does not understand the OF subobject, it
       SHOULD sends a PathErr with the error code "Routing Error" and
       error value of "Bad Explicit Route Object" toward the sender
       [RFC3209].
     
       If the processing node understands the OF subobject and the ERO
       passes the above mentioned sanity check and any other sanity
       checks associated with other ERO subobjects local to the node,
       the node takes the following actions:
     
       .  If the node supports the requested OF(s), the node expands
          the loose hop using the requested Objective Functions(s) as
          minimization criterion (criteria) for computing the route to
          the next abstract node. After processing, the OF subobjects
          are removed from the ERO. The rest of the steps for the loose
          ERO processing follow procedures outlined in [RFC3209].
       .  If the node understands the OF subobject but does not support
          any or all of the requested OF(s), it SHOULD send a Path Error
          with error code "Routing Problem" and a new error subcode
          "Unsupported Objective Function". The error subcode
          "Unsupported Objective Function" for Path Error code "Routing
          Problem" is to be assigned by IANA (Suggested Value: 107).
     
     
     
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       .  If the node understands the OF subobject and supports all of
          the requested OF(s) but cannot perform route computation with
          all objective functions considered together as optimization
          criteria for the path computation, it SHOULD send a Path Error
          with error code "Routing Problem" and a new error subcode
          "Objective Function too complex". The error subcode "Objective
          Function too complex" for Path Error code "Routing Problem" is
          to be assigned by IANA (Suggested Value: 108).
       .  If the objective function is supported but policy does not
          permit applying it, the processing node SHOULD send a Path
          Error with error code "Policy control failure" (value 2) and
          subcode "objective function not allowed". The error subcode
          "objective function not allowed" for Path Error code "Policy
          control failure" is to be assigned by IANA (Suggested Value:
          105).
     
     2.4. Processing Rules for the Metric subobject
     
        The basic processing rules of an ERO are not altered. Please
        refer to [RFC3209] for details.
     
        The scope of the Metric subobject is between the previous ERO
        subobject that identifies an abstract node, and the subsequent
        ERO subobject that identifies an abstract node.  Multiple Metric
        subobjects may be present between any pair of abstract nodes.
     
        The following conditions SHOULD result in Path Error with error
        code "Routing Problem" and error subcode "Bad EXPLICIT_ROUTE
        object":
     
       .  If the first Metric subobject is not preceded by a subobject
          identifying the next hop.
       .  If the Metric subobject follows a subobject that does not
          have the L-bit set.
     
       If the processing node does not understand the Metric subobject,
       it SHOULD sends a PathErr with the error code "Routing Error" and
       error value of "Bad Explicit Route Object" toward the sender
       [RFC3209].
     
     
     
     
     
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       If the processing node understands the Metric subobject and the
       ERO passes the above mentioned sanity check and any other sanity
       checks associated with other ERO subobjects local to the node,
       the node takes the following actions:
     
       .  For all the Metric subobject(s), the node expands the loose
          hop such that the requested metric bound(s) are met for the
          route between the two abstract nodes in the ERO. After
          processing, the Metric subobjects are removed from the ERO.
          The rest of the steps for the loose ERO processing follow
          procedure outlined in [RFC3209].
       .  If the node understands the Metric subobject but cannot find
          a route to the next abstract node such that the requested
          metric bound(s) can be satisfied, it SHOULD send a Path Error
          with error code "Routing Problem" and a new error subcode "No
          route available toward destination with the requested metric
          bounds". The error subcode "No route available toward
          destination with the requested metric bounds" for Path Error
          code "Routing Problem" is to be assigned by IANA (Suggested
          Value: 109).
     
     3. Security Considerations
     
        This document does not introduce any additional security issues
        above those identified in [RFC5920], [RFC2205], [RFC3209], and
        [RFC3473].
     
     4. IANA Considerations
     
        This document adds the following two new subobject of the
        existing entry for ERO (20, EXPLICIT_ROUTE):
     
        Value                         Description
     
        -----                         ------------
     
        TBA (suggest value: 66)       Objective Function (OF) subobject
     
        TBA (suggest value: 67)       Metric subobject
     
        These subobject may be present in the Explicit Route Object, but
        not in the Route Record Object.
     
     
     
     
     
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        OF Code values carried in OF subobject requires an IANA entry
        with suggested values as defined in section 2.1.
     
     5. Acknowledgments
     
        Authors would like to thank Matt Hartley, Ori Gerstel, Gabriele
        Maria Galimberti, Luyuan Fang and Walid Wakim for their review
        comments.
     
     6. References
     
     6.1. 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.
     
        [RFC3473] Berger, L., "Generalized Multi-Protocol Label
                  Switching (GMPLS) Signaling Resource ReserVation
                  Protocol-Traffic Engineering (RSVP-TE) Extensions",
                  RFC 3473, January 2003.
     
        [IEEE.754.1985] IEEE Standard 754, "Standard for Binary
     Floating-Point Arithmetic", August 1985.
     
     6.2. Informative References
     
        [RFC2209] Braden, R. and L. Zhang, "Resource ReSerVation
                  Protocol (RSVP) -- Version 1 Message Processing
                  Rules", RFC 2209, September 1997.
     
        [RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
                  Networks", RFC 5920, July 2010.
     
     Authors' Addresses
     
     
        Zafar Ali
        Cisco Systems.
        Email: zali@cisco.com
     
        George Swallow
        Cisco Systems.
        swallow@cisco.com
     
     
     
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        Clarence Filsfils
        Cisco Systems.
        cfilsfil@cisco.com
     
        Luyuan Fang
        Cisco Systems.
        lufang@cisco.com
     
        Rudiger Kunze
        Deutsche Telekom AG
        Ruediger.Kunze@telekom.de
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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