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Versions: (draft-wu-pce-pcep-link-bw-utilization) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 RFC 8233

PCE Working Group                                               D. Dhody
Internet-Draft                             Huawei Technologies India Pvt
Intended status: Standards Track                                     Ltd
Expires: September 27, 2013                                    V. Manral
                                                   Hewlett-Packard Corp.
                                                                  Z. Ali
                                                              G. Swallow
                                                           Cisco Systems
                                                               K. Kumaki
                                                        KDDI Corporation
                                                          March 26, 2013


Extensions to the Path Computation Element Communication Protocol (PCEP)
          to compute service aware Label Switched Path (LSP).
                  draft-ietf-pce-pcep-service-aware-00

Abstract

   In certain networks like financial information network (stock/
   commodity trading) and enterprises using cloud based applications,
   Latency (delay), Latency-Variation (jitter) and Packet loss is
   becoming a key requirement for path computation along with other
   constraints and metrics.  Latency, Latency-Variation and Packet Loss
   is associated with the Service Level Agreement (SLA) between
   customers and service providers.

   [MPLS-DELAY-FWK] describes MPLS architecture to allow Latency
   (delay), Latency-Variation (jitter) and Packet loss as properties.
   [OSPF-TE-EXPRESS] and [ISIS-TE-EXPRESS] describes mechanisms with
   which network performance information is distributed via OSPF and
   ISIS respectively.  This document describes the extension to PCEP to
   carry Latency, Latency-Variation and Loss as constraints for end to
   end path computation.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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



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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 27, 2013.

Copyright Notice

   Copyright (c) 2013 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.

































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  PCEP Requirements  . . . . . . . . . . . . . . . . . . . . . .  5
   4.  PCEP extensions  . . . . . . . . . . . . . . . . . . . . . . .  5
     4.1.  Latency (Delay) Metric . . . . . . . . . . . . . . . . . .  6
       4.1.1.  Latency (Delay) Metric Value . . . . . . . . . . . . .  6
     4.2.  Latency Variation (Jitter) Metric  . . . . . . . . . . . .  7
       4.2.1.  Latency Variation (Jitter) Metric Value  . . . . . . .  7
     4.3.  Packet Loss Metric . . . . . . . . . . . . . . . . . . . .  8
       4.3.1.  Packet Loss Metric Value . . . . . . . . . . . . . . .  9
     4.4.  Non-Understanding / Non-Support of Service Aware Path
           Computation  . . . . . . . . . . . . . . . . . . . . . . .  9
     4.5.  Mode of Operation  . . . . . . . . . . . . . . . . . . . .  9
       4.5.1.  Examples . . . . . . . . . . . . . . . . . . . . . . . 10
   5.  Relationship with Objective function . . . . . . . . . . . . . 11
   6.  Protocol Consideration . . . . . . . . . . . . . . . . . . . . 11
     6.1.  Inter domain Consideration . . . . . . . . . . . . . . . . 11
       6.1.1.  Inter-AS Link  . . . . . . . . . . . . . . . . . . . . 12
       6.1.2.  Inter-Layer Consideration  . . . . . . . . . . . . . . 12
     6.2.  Reoptimization Consideration . . . . . . . . . . . . . . . 12
     6.3.  Point-to-Multipoint (P2MP) . . . . . . . . . . . . . . . . 12
       6.3.1.  P2MP Latency Metric  . . . . . . . . . . . . . . . . . 12
       6.3.2.  P2MP Latency Variation Metric  . . . . . . . . . . . . 13
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   9.  Manageability Considerations . . . . . . . . . . . . . . . . . 14
     9.1.  Control of Function and Policy . . . . . . . . . . . . . . 14
     9.2.  Information and Data Models  . . . . . . . . . . . . . . . 14
     9.3.  Liveness Detection and Monitoring  . . . . . . . . . . . . 14
     9.4.  Verify Correct Operations  . . . . . . . . . . . . . . . . 14
     9.5.  Requirements On Other Protocols  . . . . . . . . . . . . . 14
     9.6.  Impact On Network Operations . . . . . . . . . . . . . . . 14
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 14
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 15
     11.2. Informative References . . . . . . . . . . . . . . . . . . 15
   Appendix A.  Contributor Addresses . . . . . . . . . . . . . . . . 16











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1.  Introduction

   Real time Network Performance is becoming a critical in the path
   computation in some networks.  There exist mechanism described in
   [RFC6374] to measure latency, latency-Variation and packet loss after
   the LSP has been established, which is inefficient.  It is important
   that latency, latency-variation and packet loss are considered during
   path selection process, even before the LSP is setup.

   TED is populated with network performance information like link
   latency, latency variation and packet loss through [OSPF-TE-EXPRESS]
   or [ISIS-TE-EXPRESS].  Path Computation Client (PCC) can request Path
   Computation Element (PCE) to provide a path meeting end to end
   network performance criteria.  This document extends Path Computation
   Element Communication Protocol (PCEP) [RFC5440] to handle network
   performance constraint.

   PCE MAY use mechanism described in [MPLS-TE-EXPRESS-PATH] on how to
   use the link latency, latency variation and packet loss information
   for end to end path selection.

1.1.  Requirements Language

   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.  Terminology

   The following terminology is used in this document.

   IGP:  Interior Gateway Protocol.  Either of the two routing
      protocols, Open Shortest Path First (OSPF) or Intermediate System
      to Intermediate System (IS-IS).

   IS-IS:  Intermediate System to Intermediate System.

   OSPF:  Open Shortest Path First.

   PCC:  Path Computation Client: any client application requesting a
      path computation to be performed by a Path Computation Element.

   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.





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   TE:  Traffic Engineering.

3.  PCEP Requirements

   End-to-end service optimization based on latency, latency-variation
   and packet loss is a key requirement for service provider.  Following
   key requirements associated with latency, latency-variation and loss
   are identified for PCEP:

   1.  Path Computation Element (PCE) supporting this draft MUST have
       the capability to compute end-to-end path with latency, latency-
       variation and packet loss constraints.  It MUST also support the
       combination of network performance constraint (latency, latency-
       variation, loss...) with existing constraints (cost, hop-
       limit...)

   2.  Path Computation Client (PCC) MUST be able to request for network
       performance constraint in path request message as the key
       constraint to be optimized or to suggest boundary condition that
       should not be crossed.

   3.  PCEs are not required to support service aware path computation.
       Therefore, it MUST be possible for a PCE to reject a Path
       Computation Request message with a reason code that indicates no
       support for service-aware path computation.

   4.  PCEP SHOULD provide a means to return end to end network
       performance information of the computed path in the reply
       message.

   5.  PCEP SHOULD provide mechanism to compute multi-domain (e.g.,
       Inter-AS, Inter-Area or Multi-Layer) service aware paths.

   It is assumed that such constraints are only meaningful if used
   consistently: for instance, if the delay of a computed path segment
   is exchanged between two PCEs residing in different domains,
   consistent ways of defining the delay must be used.

4.  PCEP extensions

   This section defines PCEP extensions (see [RFC5440]) for requirements
   outlined in Section 3.  The proposed solution is used to support
   network performance and service aware path computation.

   This document defines the following optional types for the METRIC
   object defined in [RFC5440].

   For explanation of these metrics, the following terminology is used



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   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)}.

4.1.  Latency (Delay) Metric

   Link delay metric is defined in [OSPF-TE-EXPRESS] and [ISIS-TE-
   EXPRESS].  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:

   - A Link delay metric of link L is denoted D(L).

   - A P2P latency metric for the Path P = Sum {D(Lpi), (i=1...K)}.

   * T=13(IANA): Latency metric

   PCC MAY use this latency metric In PCReq to request a path meeting
   the end to end latency requirement.  In this case B bit MUST be set
   to suggest a bound (a maximum) for the path latency metric that must
   not be exceeded for the PCC to consider the computed path as
   acceptable.  The path metric must be less than or equal to the value
   specified in the metric-value field.

   PCC MAY also use this metric to ask PCE to optimize delay during path
   computation, in this case B flag will be cleared.

   PCE MAY use this latency metric In PCRep along with NO-PATH object
   incase PCE cannot compute a path meeting this constraint.  PCE MAY
   also use this metric to reply the computed end to end latency metric
   to PCC.

4.1.1.  Latency (Delay) Metric Value

   [OSPF-TE-EXPRESS] and [ISIS-TE-EXPRESS] defines "Unidirectional Link
   Delay Sub-TLV" in a 24-bit field.  [RFC5440] defines the METRIC
   object with 32-bit metric value.  Consequently, encoding for Latency
   (Delay) Metric Value is defined as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Reserved      |        Latency (Delay) Metric                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Reserved (8 bits): Reserved field.  This field MUST be set to zero on



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   transmission and MUST be ignored on receipt.

   Latency (Delay) Metric (24 bits): Represents the end to end Latency
   (delay) quantified in units of microseconds and MUST be encoded as
   integer value.  With the maximum value 16,777,215 representing
   16.777215 sec.

4.2.  Latency Variation (Jitter) Metric

   Link delay variation metric is defined in [OSPF-TE-EXPRESS] and
   [ISIS-TE-EXPRESS].  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:

   - A Latency variation of link L is denoted DV(L).

   - A 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.

   * T=14(IANA): Latency Variation metric

   PCC MAY use this latency variation metric In PCReq to request a path
   meeting the end to end latency variation requirement.  In this case B
   bit MUST be set to suggest a bound (a maximum) for the path latency
   variation metric that must not be exceeded for the PCC to consider
   the computed path as acceptable.  The path metric must be less than
   or equal to the value specified in the metric-value field.

   PCC MAY also use this metric to ask PCE to optimize jitter during
   path computation, in this case B flag will be cleared.

   PCE MAY use this latency variation metric In PCRep along with NO-PATH
   object incase PCE cannot compute a path meeting this constraint.  PCE
   MAY also use this metric to reply the computed end to end latency
   variation metric to PCC.

4.2.1.  Latency Variation (Jitter) Metric Value

   [OSPF-TE-EXPRESS] and [ISIS-TE-EXPRESS] defines "Unidirectional Delay
   Variation Sub-TLV" in a 24-bit field.  [RFC5440] defines the METRIC
   object with 32-bit metric value.  Consequently, encoding for Latency
   Variation (Jitter) Metric Value is defined as follows:




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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Reserved    |     Latency variation (jitter) Metric         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Reserved (8 bits): Reserved field.  This field MUST be set to zero on
   transmission and MUST be ignored on receipt.

   Latency variation (jitter) Metric (24 bits): Represents the end to
   end Latency variation (jitter) quantified in units of microseconds
   and MUST be encoded as integer value.  With the maximum value
   16,777,215 representing 16.777215 sec.

4.3.  Packet Loss Metric

   [OSPF-TE-EXPRESS] and [ISIS-TE-EXPRESS] defines "Unidirectional Link
   Loss".  Packet Loss Metric metric type of METRIC object in PCEP
   encodes a function of the link's unidirectional loss metric of all
   links along a P2P Path.  Specifically, extending on the above
   mentioned terminology:

   The end to end Packet Loss for the path is represented by this
   metric.

   - A Packet loss of link L is denoted PL(L).

   - A P2P packet loss metric for the Path P = function {PL(Lpi),
   (i=1...K)}.

   Specification of the "Function" used to drive end to end packet loss
   metric of a path from packet loss metrics of individual links along
   the path is beyond the scope of this document.

   * T=15(IANA): Packet Loss metric

   PCC MAY use this packet loss metric In PCReq to request a path
   meeting the end to end packet loss requirement.  In this case B bit
   MUST be set to suggest a bound (a maximum) for the path packet loss
   metric that must not be exceeded for the PCC to consider the computed
   path as acceptable.  The path metric must be less than or equal to
   the value specified in the metric-value field.

   PCC MAY also use this metric to ask PCE to optimize packet loss
   during path computation, in this case B flag will be cleared.

   PCE MAY use this packet loss metric In PCRep along with NO-PATH
   object incase PCE cannot compute a path meeting this constraint.  PCE



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   MAY also use this metric to reply the computed end to end packet loss
   metric to PCC.

4.3.1.  Packet Loss Metric Value

   [OSPF-TE-EXPRESS] and [ISIS-TE-EXPRESS] defines "Unidirectional Link
   Loss Sub-TLV" in a 24-bit field.  [RFC5440] defines the METRIC object
   with 32-bit metric value.  Consequently, encoding for Packet Loss
   Metric Value is defined as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Reserved     |                Packet loss Metric             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Reserved (8 bits): Reserved field.  This field MUST be set to zero on
   transmission and MUST be ignored on receipt.

   Packet loss Metric (24 bits): Represents the end to end packet loss
   quantified as a percentage of packets lost and MUST be encoded as
   integer.  The basic unit is 0.000003%, with the maximum value
   16,777,215 representing 50.331645% (16,777,215 * 0.000003%).  This
   value is the highest packet loss percentage that can be expressed.

4.4.  Non-Understanding / Non-Support of Service Aware Path Computation

   If the P bit is clear in the object header and PCE does not
   understand or does not support service aware path computation it
   SHOULD simply ignore this METRIC.

   If the P Bit is set in the object header and PCE receives new METRIC
   type in path request and it understands the METRIC type, but the PCE
   is not capable of service aware path computation, the PCE MUST send a
   PCErr message with a PCEP-ERROR Object Error-Type = 4 (Not supported
   object) [RFC5440].  The path computation request MUST then be
   cancelled.

   If the PCE does not understand the new METRIC type, then the PCE MUST
   send a PCErr message with a PCEP-ERROR Object Error-Type = 3 (Unknown
   object) [RFC5440].

4.5.  Mode of Operation

   As explained in [RFC5440], The METRIC object is optional and can be
   used for several purposes.  In a PCReq message, a PCC MAY insert one
   or more METRIC objects:




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   o  To indicate the metric that MUST be optimized by the path
      computation algorithm (Latency, Latency-Variation or Loss)

   o  To indicate a bound on the path METRIC (Latency, Latency-Variation
      or Loss) that MUST NOT be exceeded for the path to be considered
      as acceptable by the PCC.

   In a PCRep message, the METRIC object MAY be inserted so as to
   provide the METRIC (Latency, Latency-Variation or Loss) for the
   computed path.  It MAY also be inserted within a PCRep with the NO-
   PATH object to indicate that the metric constraint could not be
   satisfied.

   The path computation algorithmic aspects used by the PCE to optimize
   a path with respect to a specific metric are outside the scope of
   this document.

   All the rules of processing METRIC object as explained in [RFC5440]
   are applicable to the new metric types as well.

   In a PCReq message, a PCC MAY insert more than one METRIC object to
   be optimized, in such a case PCE should find the path that is optimal
   when both the metrics are considered together.

4.5.1.  Examples

   Example 1: If a PCC sends a path computation request to a PCE where
   two metric to optimize are the latency and the packet loss, two
   METRIC objects are inserted in the PCReq message:

   o  First METRIC object with B=0, T=13 (TBA - IANA), C=1, metric-
      value=0x0000

   o  Second METRIC object with B=0, T=15 (TBA - IANA), C=1, metric-
      value=0x0000

   PCE in such a case should try to optimize both the metrics and find a
   path with the minimum latency and packet loss, if a path can be found
   by the PCE and there is no policy that prevents the return of the
   computed metric, the PCE inserts two METRIC object with B=0, T=13
   (TBA - IANA), metric-value= computed end to end latency and second
   METRIC object with B=1, T=15 (TBA - IANA), metric-value= computed end
   to end packet loss.

   Example 2: If a PCC sends a path computation request to a PCE where
   the metric to optimize is the latency and the packet loss must not
   exceed the value of M, two METRIC objects are inserted in the PCReq
   message:



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   o  First METRIC object with B=0, T=13 (TBA - IANA), C=1, metric-
      value=0x0000

   o  Second METRIC object with B=1, T=15 (TBA - IANA), metric-value=M

   If a path satisfying the set of constraints can be found by the PCE
   and there is no policy that prevents the return of the computed
   metric, the PCE inserts one METRIC object with B=0, T=13 (TBA -
   IANA), metric-value= computed end to end latency.  Additionally, the
   PCE may insert a second METRIC object with B=1, T=15 (TBA - IANA),
   metric-value= computed end to end packet loss.

5.  Relationship with Objective function

   [RFC5541] defines mechanism to specify an optimization criteria,
   referred to as objective functions.  The new metric types specified
   in this document can continue to use the existing Objective function.

   Minimum Cost Path (MCP) is one such objective function.

   o  A network comprises a set of N links {Li, (i=1...N)}.

   o  A path P is a list of K links {Lpi,(i=1...K)}.

   o  Metric of link L is denoted M(L).  This can be any metric,
      including the ones defined in this document.

   o  The cost of a path P is denoted C(P), where C(P) = sum
      {M(Lpi),(i=1...K)}.

   Name: Minimum Cost Path (MCP)

   Description: Find a path P such that C(P) is minimized.

   The new metric types for example latency (delay) can continue to use
   the above objective function to find the minimum cost path where cost
   is latency (delay).  At the same time new objective functions can be
   defined in future to optimize these new metric types.

6.  Protocol Consideration

   There is no change in the message format of Path Request and Reply
   Message.

6.1.  Inter domain Consideration

   [RFC5441] describes the BRPC procedure to compute end to end
   optimized inter domain path by cooperating PCEs.  The network



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   performance constraints can be applied end to end in similar manner
   as IGP or TE cost.

   All domains should have the same understanding of the METRIC
   (Latency-Variation etc) for end-to-end inter-domain path computation
   to make sense.  Otherwise some form of Metric Normalization as
   described in [RFC5441] MAY need to be applied.

6.1.1.  Inter-AS Link

   The IGP in each neighbor domain can advertise its inter-domain TE
   link capabilities, this has been described in [RFC5316] (ISIS) and
   [RFC5392] (OSPF).  The network performance link properties are
   described in [OSPF-TE-EXPRESS] and [ISIS-TE-EXPRESS], the same
   properties must be advertised using the mechanism described in
   [RFC5392] (OSPF) and [RFC5316] (ISIS).

6.1.2.  Inter-Layer Consideration

   PCEP supporting this draft SHOULD provide mechanism to support
   different Metric requirements for different Layers.  This is
   important as the network performance metric would be different for
   Packet and Optical (TDM, LSC etc) Layers.  In order to allow
   different Metric-Value to be applied within different network layers,
   multiple METRIC objects of the same type MAY be present.  In such a
   case, the first METRIC object specifies an metric for the higher-
   layer network, and subsequent METRIC objects specify objection
   functions of the subsequent lower-layer networks.

6.2.  Reoptimization Consideration

   PCC can monitor the setup LSPs and incase of degradation of network
   performance constraints, it MAY ask PCE for reoptimization as per
   [RFC5440].

6.3.  Point-to-Multipoint (P2MP)

   This document defines the following optional types for the METRIC
   object defined in [RFC5440] for P2MP TE LSPs.  Additional metric
   types for P2MP TE LSPs are to be added in a future revision

6.3.1.  P2MP Latency Metric

   P2MP latency metric type of METRIC object in PCEP encodes the path
   latency metric for destination that observes the worst latency metric
   among all destination of the P2MP tree.  Specifically, extending on
   the above mentioned terminology:




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   - 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

6.3.2.  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

7.  IANA Considerations

   IANA has defined a registry for new METRIC type.

                 Type        Meaning
                 13(TBD)     Latency (delay) metric
                 14(TBD)     Latency Variation (jitter) metric
                 15(TBD)     Packet Loss metric
                 16(TBD)     P2MP latency metric
                 17(TBD)     P2MP latency variation metric


8.  Security Considerations

   This document defines three new METRIC Types which does not add any
   new security concerns to PCEP protocol.






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9.  Manageability Considerations

9.1.  Control of Function and Policy

   The only configurable item is the support of the new service-aware
   METRICS on a PCE which MAY be controlled by a policy module.  If the
   new METRIC is not supported/allowed on a PCE, it MUST send a PCErr
   message as specified in Section 4.4.

9.2.  Information and Data Models

   [PCEP-MIB] describes the PCEP MIB, there are no new MIB Objects for
   this document.

9.3.  Liveness Detection and Monitoring

   Mechanisms defined in this document do not imply any new liveness
   detection and monitoring requirements in addition to those already
   listed in [RFC5440].

9.4.  Verify Correct Operations

   Mechanisms defined in this document do not imply any new operation
   verification requirements in addition to those already listed in
   [RFC5440].

9.5.  Requirements On Other Protocols

   PCE requires the TED to be populated with network performance
   information like link latency, latency variation and packet loss.
   This mechanism is described in [OSPF-TE-EXPRESS] or
   [ISIS-TE-EXPRESS].

9.6.  Impact On Network Operations

   Mechanisms defined in this document do not have any impact on network
   operations in addition to those already listed in [RFC5440].

10.  Acknowledgments

   We would like to thank Young Lee, Venugopal Reddy, Reeja Paul,
   Sandeep Kumar Boina, Suresh babu, Quintin Zhao and Chen Huaimo for
   their useful comments and suggestions.

11.  References






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11.1.  Normative References

   [RFC2119]               Bradner, S., "Key words for use in RFCs to
                           Indicate Requirement Levels", BCP 14,
                           RFC 2119, March 1997.

   [RFC5440]               Vasseur, JP. and JL. Le Roux, "Path
                           Computation Element (PCE) Communication
                           Protocol (PCEP)", RFC 5440, March 2009.

11.2.  Informative References

   [RFC5441]               Vasseur, JP., Zhang, R., Bitar, N., and JL.
                           Le Roux, "A Backward-Recursive PCE-Based
                           Computation (BRPC) Procedure to Compute
                           Shortest Constrained Inter-Domain Traffic
                           Engineering Label Switched Paths", RFC 5441,
                           April 2009.

   [RFC5316]               Chen, M., Zhang, R., and X. Duan, "ISIS
                           Extensions in Support of Inter-Autonomous
                           System (AS) MPLS and GMPLS Traffic
                           Engineering", RFC 5316, December 2008.

   [RFC5392]               Chen, M., Zhang, R., and X. Duan, "OSPF
                           Extensions in Support of Inter-Autonomous
                           System (AS) MPLS and GMPLS Traffic
                           Engineering", RFC 5392, January 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.

   [RFC6374]               Frost, D. and S. Bryant, "Packet Loss and
                           Delay Measurement for MPLS Networks",
                           RFC 6374, September 2011.

   [MPLS-DELAY-FWK]        Fu, X., Manral, V., McDysan, D., Malis, A.,
                           Giacalone, S., Betts, M., Wang, Q., and J.
                           Drake, "Traffic Engineering architecture for
                           services aware MPLS
                           [draft-fuxh-mpls-delay-loss-te-framework]",
                           Oct 2012.

   [OSPF-TE-EXPRESS]       Giacalone, S., Ward, D., Drake, J., Atlas,
                           A., and S. Previdi, "OSPF Traffic Engineering
                           (TE) Metric Extensions



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                           [draft-ietf-ospf-te-metric-extensions]",
                           May 2012.

   [ISIS-TE-EXPRESS]       Previdi, S., Giacalone, S., Ward, D., Drake,
                           J., Atlas, A., and C. Filsfils, "IS-IS
                           Traffic Engineering (TE) Metric Extensions
                           [draft-previdi-isis-te-metric-extensions]",
                           Oct 2012.

   [MPLS-TE-EXPRESS-PATH]  Atlas, A., Drake, J., Ward, D., Giacalone,
                           S., Previdi, S., and C. Filsfils,
                           "Performance-based Path Selection for
                           Explicitly Routed LSPs
                           [draft-atlas-mpls-te-express-path]",
                           June 2012.

   [PCEP-MIB]              Kiran Koushik, A S., Stephan, E., Zhao, Q.,
                           King, D., and J. Hardwick, "PCE communication
                           protocol(PCEP) Management Information Base
                           [draft-ietf-pce-pcep-mib]", July 2012.

Appendix A.  Contributor Addresses


   Clarence Filsfils
   Cisco Systems
   EMail: cfilsfil@cisco.com

   Siva Sivabalan
   Cisco Systems
   EMail: msiva@cisco.com

   Stefano Previdi
   Cisco Systems
   EMail: sprevidi@cisco.com

   Udayasree Palle
   Huawei Technologies India Pvt Ltd
   Leela Palace
   Bangalore, Karnataka  560008
   INDIA
   EMail: udayasree.palle@huawei.com









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Authors' Addresses

   Dhruv Dhody
   Huawei Technologies India Pvt Ltd
   Leela Palace
   Bangalore, Karnataka  560008
   INDIA

   EMail: dhruv.dhody@huawei.com


   Vishwas Manral
   Hewlett-Packard Corp.
   191111 Pruneridge Ave.
   Cupertino, CA  95014
   USA

   EMail: vishwas.manral@hp.com


   Zafar Ali
   Cisco Systems


   EMail: zali@cisco.com


   George Swallow
   Cisco Systems


   EMail: swallow@cisco.com


   Kenji Kumaki
   KDDI Corporation


   EMail: ke-kumaki@kddi.com












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