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     CCAMP Working Group                                       Zafar Ali
     Internet Draft                                       George Swallow
     Intended status: Standard Track                   Clarence Filsfils
     Expires: April 14, 2013                              Siva Sivabalan
                                                         Stefano Previdi
                                                           Cisco Systems
                                                            Kenji Kumaki
                                                        KDDI Corporation
                                                        October 15, 2012
     
     
     
            Additional Objective Functions and Metric Types in Path
               Computation Element Communication Protocol (PCEP)
                 draft-ali-pce-additional-of-and-metric-00.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 April 14, 2013.
     
     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
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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
     
     Network performance criteria such as latency and latency variation
     are becoming critical to data path selection, especially for
     networks used by financial institutions. This draft defines
     additional objective functions and metrics types related to latency
     and latency variation in Path Computation Element Communication
     Protocol (PCEP).
     
     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. PCEP extensions................................................3
           2.1. New Metric Object Types................................3
              2.1.1. P2P Latency Metric................................4
              2.1.2. P2P Latency Variation Metric......................4
              2.1.3. P2MP Latency Metric...............................4
              2.1.4. P2MP Latency Variation Metric.....................5
           2.2. Handling of New Metric Object Types....................5
           2.3. New Objective Functions................................5
              2.3.1. Minimum Latency Path Objective Function...........6
              2.3.2. Minimum Latency Variation Path Objective Function.6
           2.4. Handling of New Objective Functions....................6
     3. Security Considerations........................................6
     
     
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     4. IANA Considerations............................................6
     5. References.....................................................7
           5.1. Normative References...................................7
           5.2. Informative References.................................7
     
     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), performance criteria (e.g. latency,
       latency variation) are becoming critical to data path selection
       along with other metrics. Such networks may require selection of
       a path that minimizes end-to-end latency and/or end-to-end
       latency variation. Or a path may need to be found that optimizes
       some other metric, but is subjected to a latency and/or latency
       variation bound(s).
     
       The METRIC object defined in [RFC5440] allows a PCC to specify a
       bounded acceptable path cost and/or optimization metric. While
       [RFC5440], [RFC5541] and [RFC6006] define various Metric Types,
       these RFCs do not address latency and latency variation metrics.
       This document extends [RFC 5540] with four new Metric Types
       namely Point-to-Point (P2P) latency metric, P2P latency variation
       metric, Point-to-Multipoint (P2MP) latency metric and P2MP
       latency variation metric.
     
       [RFC5541] defines a framework to extend the PCEP to allow a PCE
       to indicate the set of objective functions it supports. [RFC5541]
       also define procedure so that a PCC can indicate in a path
       computation request the required objective function, and a PCE
       can report in a path computation reply the objective function
       that was used for path computation. While [RFC5541] and [RFC6006]
       define various objective functions, these documents do not define
       objective functions for optimizing network performance criteria
       such as latency and latency variation. This document extends the
       [RFC5541] with two new objective functions namely Minimum Latency
       Path (MLP) OF and Minimum Latency Variation Path (MLVP) OF.
     
     2. PCEP extensions
     
        This section defines PCEP extensions for requirements outlined
        in Section 1.
     
     2.1. New Metric Object Types
     
           This document defines the following four additional types for
        the <METRIC> object defined in [RFC5440}. For explanation of
     
     
     
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        these metrics, the following terminology is used and expanded
        along the way.
     
          - A network comprises of a set of N links {Li, (i=1...N)}.
     
          - A path P of a P2P LSP is a list of K links {Lpi,(i=1...K)}.
     
     2.1.1. P2P Latency Metric
     
        Link delay metric is defined in [OSPF-TE-METRIC] and [ISIS-TE-
        METRIC]. P2P latency metric type of <METRIC> object in PCEP
        encodes the sum of the link delay metric of all links along a
        P2P Path. Specifically, extending on the above mentioned
        terminology:
     
          -  Link delay metric of link L is denoted D(L).
     
          -  P2P latency metric for the Path P = Sum {D(Lpi),
            (i=1...K)}.
     
        Value for P2P latency metric type is to be assigned by IANA
        (suggested value: 11).
     
     2.1.2. P2P Latency Variation Metric
     
        Link delay variation metric is defined in [OSPF-TE-METRIC] and
        [ISIS-TE-METRIC]. P2P latency variation metric type of <METRIC>
        object in PCEP encodes a function of the link delay variation
        metric of all links along a P2P Path. Specifically, extending on
        the above mentioned terminology:
     
          -  Latency variation of link L is denoted DV(L).
     
          -  P2P latency variation metric for the Path P = Function
            {DV(Lpi), (i=1...K)}.
     
        Specification of the "Function" used to drive latency variation
        metric of a path from latency variation metrics of individual
        links along the path is beyond the scope of this document.
     
        Value for P2P latency variation metric is to be assigned by IANA
        (suggested value: 12).
     
     2.1.3. P2MP Latency Metric
     
       P2MP latency metric type of <METRIC> object in PCEP encodes the
       path latency metric for destination that observes the worst
     
     
     
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       latency metric among all destination of the P2MP tree.
       Specifically, extending on the above mentioned terminology:
     
         - A P2MP Tree T comprises of a set of M destinations {Dest_j,
           (j=1...M)}
     
         - P2P latency metric of the Path to destination Dest_j is
           denoted by LM(Dest_j).
     
         - P2MP latency metric for the P2MP tree T = Maximum
           {LM(Dest_j), (j=1...M)}.
     
       Value for P2MP latency metric is to be assigned by IANA
       (suggested value: 13).
     
     2.1.4. P2MP Latency Variation Metric
     
       P2MP latency variation metric type of <METRIC> object in PCEP
       encodes the path latency variation metric for destination that
       observes the worst latency variation metric among all destination
       of the P2MP tree. Specifically, extending on the above mentioned
       terminology:
     
         - A P2MP Tree T comprises of a set of M destinations {Dest_j,
           (j=1...M)}
     
         - P2P latency variation metric of the Path to destination
           Dest_j is denoted by LVM(Dest_j).
     
         - P2MP latency variation metric for the P2MP tree T = Maximum
           {LVM(Dest_j), (j=1...M)}.
     
       Value for P2MP latency variation metric is to be assigned by IANA
       (suggested value: 14).
     
     2.2. Handling of New Metric Object Types
     
        This document does not propose any changes to handling of Metric
        object. Specifically, the new metric types defined in this
        document are handled in the same fashion as metric types defined
        in [RFC5440].
     
     2.3. New Objective Functions
     
        This document extends the [RFC 5541] with two new objective
        functions namely Minimum Latency Path (MLP) OF and Minimum
        Latency Variation Path (MLVP) OF. The objective function code
        for each of the new objective function is also defined.
     
     
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     2.3.1. 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.
     
        Objective function code for MLP OF is to be assigned by IANA
        (suggested value: 9).
     
     2.3.2. 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.
     
        Objective function code for MLVP OF is to be assigned by IANA
        (suggested value: 10).
     
     2.4. Handling of New Objective Functions
     
        This document does not propose any changes to handling of <OF>
        object. Specifically, the new OF types defined in this document
        are handled in the same fashion as OF types defined in
        [RFC5541].
     
     3. Security Considerations
     
        This document does not introduce any additional security issues
        beyond those identified in [RFC5440], [RFC5541] and [RFC6006].
     
     4. IANA Considerations
     
        This document defines the following four additional types for
        the <METRIC> object defined in [RFC5440].
     
        Value                         Description
     
        -----                         ------------
     
        TBA (suggest value: 11)       P2P latency metric
     
        TBA (suggest value: 12)       P2P latency variation metric
     
        TBA (suggest value: 13)       P2MP latency metric
     
        TBA (suggest value: 14)       P2MP latency variation metric
     
     
     
     
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        This document defines the following two objective functions
        codes for the <OF> object defined in [RFC5541].
     
        Value                   Description
     
        -----                   ------------
     
        TBA (suggest value: 9)  Minimum Latency Path (MLP) OF
     
        TBA (suggest value: 10) Minimum Latency Variation Path (MLVP) OF
     
     
     5. References
     
     5.1. Normative References
     
        [RFC5440] Vasseur, JP., Ed., and JL. Le Roux, Ed., "Path
                  Computation Element (PCE) Communication Protocol
                  (PCEP)", RFC 5440, March 2009.
     
        [RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
                  Objective Functions in the Path Computation Element
                  Communication Protocol (PCEP)", RFC 5541, June 2009.
     
        [DRAFT-OSPF-TE-METRIC] S. Giacalone, D. Ward, J. Drake, A.
                  Atlas, S. Previdi, "OSPF Traffic Engineering (TE)
                  Metric Extensions", draft-ietf-ospf-te-metric-
                  extensions, work in progress.
     
        [DRAFT-ISIS-TE-METRIC] S. Previdi, S. Giacalone, D. Ward, J.
                  Drake, A. Atlas, C. Filsfils, "IS-IS Traffic
                  Engineering (TE) Metric Extensions", draft-previdi-
                  isis-te-metric-extensions, work in progress.
     
     
     5.2. Informative References
     
        [RFC6006] Zhao, Q., Ed., King, D., Ed., Verhaeghe, F., Takeda,
                  T., Ali, Z., and J. Meuric, "Extensions to the Path
                  Computation Element Communication Protocol (PCEP) for
                  Point-to-Multipoint Traffic Engineering Label Switched
                  Paths", RFC 6006, September 2010.
     
     Authors' Addresses
     
     
     
     
     
     
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        Zafar Ali
        Cisco Systems
        Email: zali@cisco.com
     
        George Swallow
        Cisco Systems
        swallow@cisco.com
     
        Clarence Filsfils
        Cisco Systems
        cfilsfil@cisco.com
     
        Siva Sivabalan
        Cisco Systems
        msiva@cisco.com
     
        Stefano Previdi
        Cisco Systems
        sprevidi@cisco.com
     
        Kenji Kumaki
        KDDI Corporation
        Email: ke-kumaki@kddi.com
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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