Internet DRAFT - draft-dhody-pce-stateful-pce-auto-bandwidth

draft-dhody-pce-stateful-pce-auto-bandwidth



 



PCE Working Group                                               D. Dhody
Internet-Draft                                                  U. Palle
Intended status: Standards Track                     Huawei Technologies
Expires: August 30, 2016                                        R. Singh
                                                        Juniper Networks
                                                               R. Gandhi
                                                     Cisco Systems, Inc.
                                                                 L. Fang
                                                               Microsoft
                                                       February 29, 2016


  PCEP Extensions for MPLS-TE LSP Automatic Bandwidth Adjustment with
                              Stateful PCE
             draft-dhody-pce-stateful-pce-auto-bandwidth-07

Abstract

   The Path Computation Element Communication Protocol (PCEP) provides
   mechanisms for Path Computation Elements (PCEs) to perform path
   computations in response to Path Computation Clients (PCCs) requests.
    The stateful PCE extensions allow stateful control of Multi-Protocol
   Label Switching (MPLS) Traffic Engineering Label Switched Paths (TE
   LSPs) using PCEP.

   This document describes PCEP extensions for automatic bandwidth
   adjustment when employing an Active Stateful PCE for both PCE-
   initiated and PCC-initiated LSPs.  In one of the models described,
   PCC computes the bandwidth to be adjusted and informs the PCE whereas
   in the second model, PCC reports the real-time bandwidth usage to a
   PCE and the PCE computes the adjustment bandwidth. 


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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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

 


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Copyright Notice

   Copyright (c) 2016 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  5
     2.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  5
     2.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Requirements for PCEP Extensions . . . . . . . . . . . . . . .  6
   4.  Architectural Overview . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Auto-Bandwidth Overview  . . . . . . . . . . . . . . . . .  7
     4.2.  Theory of Operation  . . . . . . . . . . . . . . . . . . . 10
     4.3.  Scaling Considerations . . . . . . . . . . . . . . . . . . 11
   5.  Extensions to the PCEP . . . . . . . . . . . . . . . . . . . . 11
     5.1.  Capability Advertisement . . . . . . . . . . . . . . . . . 11
       5.1.1 AUTO-BANDWIDTH-CAPABILITY TLV  . . . . . . . . . . . . . 12
     5.2.  AUTO-BANDWIDTH-ATTRIBUTE TLV . . . . . . . . . . . . . . . 12
       5.2.1.  Sample-Interval sub-TLV  . . . . . . . . . . . . . . . 14
       5.2.2.  Adjustment-Interval sub-TLV  . . . . . . . . . . . . . 14
       5.2.3.  Adjustment Threshold . . . . . . . . . . . . . . . . . 15
         5.2.3.1.  Adjustment-Threshold sub-TLV . . . . . . . . . . . 15
         5.2.3.2.  Adjustment-Threshold-Percentage sub-TLV  . . . . . 15
       5.2.4.  Minimum and Maximum Bandwidth Values . . . . . . . . . 16
         5.2.4.1.  Minimum-Bandwidth sub-TLV  . . . . . . . . . . . . 16
         5.2.4.2.  Maximum-Bandwidth sub-TLV  . . . . . . . . . . . . 16
       5.2.5.  Overflow and Underflow Condition . . . . . . . . . . . 17
         5.2.5.1.  Overflow-Threshold sub-TLV . . . . . . . . . . . . 17
         5.2.5.2.  Overflow-Threshold-Percentage sub-TLV  . . . . . . 18
         5.2.5.3.  Underflow-Threshold sub-TLV  . . . . . . . . . . . 18
         5.2.5.4.  Underflow-Threshold-Percentage sub-TLV . . . . . . 19
     5.3.  BANDWIDTH-USAGE-ATTRIBUTE TLV  . . . . . . . . . . . . . . 20
       5.3.1.  Bandwidth-Usage-Report-Interval sub-TLV  . . . . . . . 21
       5.3.2.  Bandwidth-Usage-Report-Threshold sub-TLV . . . . . . . 22
 


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       5.3.3.  Bandwidth-Usage-Report-Threshold-Percentage sub-TLV  . 22
       5.3.4.  Bandwidth-Usage-Report-Flow-Threshold sub-TLV  . . . . 23
       5.3.5.  Bandwidth-Usage-Report-Flow-Threshold-Percent 
               sub-TLV  . . . . . . . . . . . . . . . . . . . . . . . 24
     5.4.  BANDWIDTH Object . . . . . . . . . . . . . . . . . . . . . 24
       5.4.1.  Auto-Bandwidth Adjusted Bandwidth Report . . . . . . . 24
       5.4.2.  Bandwidth-Usage Report . . . . . . . . . . . . . . . . 25
     5.5.  The PCInitiate Message . . . . . . . . . . . . . . . . . . 25
     5.6.  The PCRpt Message  . . . . . . . . . . . . . . . . . . . . 26
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 26
   7.  Manageability Considerations . . . . . . . . . . . . . . . . . 26
     7.1.  Control of Function and Policy . . . . . . . . . . . . . . 26
     7.2.  Information and Data Models  . . . . . . . . . . . . . . . 27
     7.3.  Liveness Detection and Monitoring  . . . . . . . . . . . . 27
     7.4.  Verify Correct Operations  . . . . . . . . . . . . . . . . 27
     7.5.  Requirements On Other Protocols  . . . . . . . . . . . . . 27
     7.6.  Impact On Network Operations . . . . . . . . . . . . . . . 27
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 28
     8.1.  PCEP TLV Type Indicators . . . . . . . . . . . . . . . . . 28
     8.2.  AUTO-BANDWIDTH-ATTRIBUTE Sub-TLV . . . . . . . . . . . . . 28
     8.3.  BANDWIDTH-USAGE-ATTRIBUTE Sub-TLV  . . . . . . . . . . . . 28
     8.4.  BANDWIDTH Object . . . . . . . . . . . . . . . . . . . . . 29
     8.5.  Error Object . . . . . . . . . . . . . . . . . . . . . . . 29
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 29
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 30
   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . . . 31
   Contributors' Addresses  . . . . . . . . . . . . . . . . . . . . . 31
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 32


1.  Introduction

   [RFC5440] describes the Path Computation Element Protocol (PCEP) as a
   communication mechanism between a Path Computation Client (PCC) and a
   Path Control Element (PCE), or between PCE and PCE, that enables
   computation of Multi-Protocol Label Switching (MPLS) Traffic
   Engineering Label Switched Paths (TE LSPs).

   [I-D.ietf-pce-stateful-pce] specifies extensions to PCEP to enable
   stateful control of MPLS TE LSPs.  It describes two mode of
   operations - Passive Stateful PCE and Active Stateful PCE.  In this
   document, the focus is on Active Stateful PCE where LSPs are
   configured at the PCC and control over them is delegated to the PCE. 
   Further [I-D.ietf-pce-pce-initiated-lsp] describes the setup,
   maintenance and teardown of PCE-initiated LSPs for the stateful PCE
   model.

 


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   Over time, based on the varying traffic pattern, an LSP established
   with certain bandwidth may require to adjust the bandwidth, reserved
   in the network automatically.  Ingress Label Switch Router (LSR)
   collects the traffic rate at each sample interval to determine the
   bandwidth demand of the LSP.  This bandwidth information is then used
   to adjust the LSP bandwidth periodically.  This feature is commonly
   referred to as Auto-Bandwidth.

   Enabling Auto-Bandwidth feature on an LSP results in the LSP
   automatically adjusting its bandwidth reservation based on the actual
   traffic flowing through the LSP.  The initial LSP bandwidth can be
   set to an arbitrary value (including zero), in practice, it can be
   operator expected value based on design and planning.  Once the LSP
   is set-up, the LSP monitors the traffic flow and adjusts its
   bandwidth every adjustment-interval period.  The bandwidth adjustment
   uses the make-before-break signaling method so that there is no
   interruption to the traffic flow.  The Auto-Bandwidth is described in
   detail in Section 4.1.  [I-D.ietf-pce-stateful-pce-app] describes the
   use-case for Auto-Bandwidth adjustment for passive and active
   stateful PCE.


   In this document, following deployment models are considered for
   employing Auto-Bandwidth feature with active stateful PCE.

   o  Deployment model 1: PCC to decide adjusted bandwidth:

      *  In this model, the PCC (head-end of the LSP) monitors and
         calculates the new adjusted bandwidth.  The PCC reports the
         calculated bandwidth to be adjusted to the PCE.

      *  This approach would be similar to passive stateful PCE model,
         while the passive stateful PCE uses path request/reply
         mechanism, the active stateful PCE uses report/update mechanism
         to adjust the LSP bandwidth.

      *  For PCE-initiated LSP, the PCC is requested during the LSP
         initiation to monitor and calculate the new adjusted bandwidth.

   o  Deployment model 2: PCE to decide adjusted bandwidth:

      *  In this model, the PCE calculates the new adjusted bandwidth
         for the LSP.

      *  Active stateful PCE can use information such as historical
         trending data, application-specific information about expected
         demands and central policy information along with real-time
         bandwidth usage to make smarter bandwidth adjustment to the
 


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         delegated LSPs.  Since the LSP has delegated control to the
         PCE, it is inherently suited that it should be the stateful PCE
         that decides the bandwidth adjustments.

      *  For PCE-initiated LSP, the PCC is requested during initiation,
         to monitor and report the real-time bandwidth usage.

      *  This model does not exclude use of any other mechanism employed
         by stateful PCE to learn real-time bandwidth usage information.
          But at the same time, using the same protocol (PCEP in this
         case) for updating and reporting the adjustment parameters as
         well as to learn real-time bandwidth usage is operationally
         beneficial.

   This document defines extensions needed to support Auto-Bandwidth
   feature on the LSPs in a active stateful PCE model using PCEP.


2.  Conventions Used in This Document

2.1.  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].

2.2.  Terminology

   The following terminology is used in this document.

   Active Stateful PCE:  PCE that uses tunnel state information learned
      from PCCs to optimize path computations.  Additionally, it
      actively updates tunnel parameters in those PCCs that delegated
      control over their tunnels to the PCE.

   Delegation:  An operation to grant a PCE temporary rights to modify a
      subset of tunnel parameters on one or more PCC's tunnels.  Tunnels
      are delegated from a PCC to a PCE.

   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.

   TE LSP:  Traffic Engineering Label Switched Path.
 


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   Note the Auto-Bandwidth feature specific terms defined in Section
   4.1.

3.  Requirements for PCEP Extensions

   The PCEP speaker supporting this document MUST have a mechanism to
   advertise the automatic bandwidth adjustment capability. 

   As discussed in Section 1, there are two deployment models considered
   in this document for automatic bandwidth adjustments in case of
   active stateful PCE.  In the model 1, where PCC decides the adjusted
   bandwidth, PCC reports the new adjusted bandwidth and an active
   stateful PCE updates the bandwidth of a delegated LSP via existing
   mechanisms defined in [I-D.ietf-pce-stateful-pce].  PCEP extensions
   required for both models are summarized in the following table.

   +-------------------------------------------------------------------+
   | Model 1: PCC decides adjusted BW                                  |
   +---------------------------------+---------------------------------+
   | PCC Initiated                   | PCE Initiated                   |
   +---------------------------------+---------------------------------+
   |                                 |                                 |
   | PCC monitors the traffic        | At the time of initiation,      |
   | and reports the calculated      | PCE request PCC to monitor      |
   | bandwidth to be adjusted        | the traffic and report the      |
   | to the PCE.                     | calculated bandwidth to be      |
   |                                 | adjusted to the PCE.            |
   |                                 |                                 |
   | No new extensions are needed.   | Extension is needed for PCE     |
   |                                 | to pass on the adjustment       |
   |                                 | parameters at the time of       |
   |                                 | Initiation.                     |
   |                                 |                                 |
   +---------------------------------+---------------------------------+

   +-------------------------------------------------------------------+
   | Model 2: PCC reports bandwidth-usage, PCE decides adjusted BW     |
   +---------------------------------+---------------------------------+
   |  PCC Initiated                  | PCE Initiated                   |
   +---------------------------------+---------------------------------+
   |                                 |                                 |
   | PCC monitors bandwidth usage    | At the time of initiation,      |
   | and reports the real-time       | PCE request PCC to monitor      |
   | bandwidth usage to the PCE.     | the traffic and reports the     |
   | It is PCE that decides the      | real-time bandwidth usage to    |
   | calculated bandwidth to be      | the PCE.  It is PCE that decides|
   | adjusted and updates the        | the calculated bandwidth to     |
   | LSP accordingly.                | be adjusted and updates the     |
 


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   |                                 | LSP accordingly.                |
   |                                 |                                 |
   | Extension is needed for         | Extension is needed for PCE     |
   | PCC to pass on the auto-bw      | to pass on the real-time        |
   | adjustment parameters at        | bandwidth usage reporting       |
   | the time of delegation to       | parameters at the time of       |
   | PCE.                            | Initiation.                     |
   |                                 |                                 |
   | Further extension to report     | Further extension to report     |
   | the bandwidth-usage to          | the bandwidth-usage to          |
   | PCE are also needed             | PCE are also needed.            |
   |                                 |                                 |
   +---------------------------------+---------------------------------+

                 Table 1: Auto-Bandwidth PCEP extensions

   Further Auto-Bandwidth deployment considerations are summarized
   below:

   o  It is required to identify and inform the PCEP peer, the LSP that
      are enabled with Auto-Bandwidth feature.  Not all LSPs in some
      deployments would like their bandwidth to be dependent on the
      real-time bandwidth usage but be constant as set by the operator.

   o  It is also required to identify and inform the PCEP peer the model
      of operation i.e. if PCC decides the adjusted bandwidth, or PCC
      reports the real-time bandwidth usage instead and the PCE decides
      the adjusted bandwidth.

      *  Note that PCEP extension for reporting real-time bandwidth
         usage, as specified in this document, is one of the ways for a
         PCE to learn this information.  But at the same time a stateful
         PCE may choose to learn this information from other means like
         management, performance tools, which are beyond the scope of
         this document.

   o  Further for the LSP with Auto-Bandwidth feature enabled, an
      operator should be able to specify the adjustment parameters (i.e.
      configuration knobs) to control this feature (e.g.  minimum/
      maximum bandwidth range) and PCEP peer should be informed.



4.  Architectural Overview

4.1.  Auto-Bandwidth Overview

   Auto-Bandwidth feature allows an LSP to automatically and dynamically
 


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   adjust its reserved bandwidth over time, i.e. without network
   operator intervention.  The bandwidth adjustment uses the
   make-before-break signaling method so that there is no interruption
   to the traffic flow.

   The new bandwidth reservation is determined by sampling the actual
   traffic flowing through the LSP.  If the traffic flowing through the
   LSP is lower than the configured or current bandwidth of the LSP, the
   extra bandwidth is being reserved needlessly and being wasted.
   Conversely, if the actual traffic flowing through the LSP is higher
   than the configured or current bandwidth of the LSP, it can
   potentially cause congestion or packet loss in the network.  With
   Auto-Bandwidth feature, the LSP bandwidth can be set to some
   arbitrary value (including zero) during initial setup time, and it
   will be periodically adjusted over time based on the actual bandwidth
   requirement.

   Note the following definitions of the Auto-Bandwidth terms:

   Maximum Average Bandwidth (MaxAvgBw):  The maximum average bandwidth
      represents the current traffic bandwidth demand during a time
      interval.  This is the maximum value of the averaged traffic
      bandwidth rate in a given adjustment-interval.

   Adjusted Bandwidth:  This is the Auto-Bandwidth computed bandwidth
      that needs to be adjusted for the LSP.

   Sample-Interval:  The periodic time interval at which the traffic
      rate is collected as a sample.

   Bandwidth-Sample (BwSample):  The bandwidth sample collected at every
      sample interval to measure the traffic rate.

   Adjustment-Interval:  The periodic time interval at which the
      bandwidth adjustment should be made using the MaxAvgBw.

   Maximum-Bandwidth:  The maximum bandwidth that can be reserved for
      the LSP.

   Minimum-Bandwidth:  The minimum bandwidth that can be reserved for
      the LSP.

   Adjustment-Threshold:  This value is used to decide when the
      bandwidth should be adjusted.  If the percentage or absolute
      difference between the current MaxAvgBw and the current bandwidth
      reservation is greater than or equal to the threshold value, the
      LSP bandwidth is adjusted to the current bandwidth demand
      (Adjusted Bandwidth) at the adjustment-interval expiry.
 


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   Overflow-Count:  This value is used to decide when the bandwidth
      should be adjusted when there is a sudden increase in traffic
      demand.  This value indicates how many times consecutively, the
      percentage or absolute difference between the current MaxAvgBw and
      the current bandwidth reservation is greater than or equal to the
      Overflow-Threshold value.  

   Overflow-Threshold:  This value is used to decide when the bandwidth
      should be adjusted when there is a sudden increase in traffic
      demand.  If the percentage or absolute difference between the
      current MaxAvgBw and the current bandwidth reservation is greater
      than or equal to the threshold value, the overflow-condition is
      set to be met.  The LSP bandwidth is adjusted to the current
      bandwidth demand bypassing the adjustment-interval if the
      overflow-condition is met consecutively for the Overflow-Count.

   Underflow-Count:  This value is used to decide when the bandwidth
      should be adjusted when there is a sudden decrease in traffic
      demand.  This value indicates how many times consecutively, the
      percentage or absolute difference between the current MaxAvgBw and
      the current bandwidth reservation is greater than or equal to the
      Underflow-Threshold value.  

   Underflow-Threshold:  This value is used to decide when the bandwidth
      should be adjusted when there is a sudden decrease in traffic
      demand.  If the percentage or absolute difference between the
      current MaxAvgBw and the current bandwidth reservation is greater
      than or equal to the threshold value, the underflow-condition is
      set to be met.  The LSP bandwidth is adjusted to the current
      bandwidth demand bypassing the adjustment-interval if the
      underflow-condition is met consecutively for the Underflow-Count.

   Report-Interval:  This value indicates the periodic interval when the
      collected real-time bandwidth-usage samples (BwSample) should be
      reported to the stateful PCE via the PCRpt message.

   Report-Threshold:  This value is used to decide if the real-time
      bandwidth-usage samples collected should be reported.  Only if the
      percentage or the absolute difference between at least one of the
      bandwidth samples collected and the current bandwidth reservation
      is greater than or equal to the threshold value, the bandwidth
      samples collected during the Report-Interval are reported
      otherwise the bandwidth sample(s) are skipped.

   Report-Flow-Threshold:  This value is used to decide when the real-
      time traffic bandwidth samples should be reported immediately when
      there is a sudden change in traffic demand.  If the percentage or
      absolute difference between the current bandwidth sample and the
 


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      current bandwidth reservation is greater than or equal to the
      flow-threshold value, the bandwidth usage report condition is said
      to be met.  The collected bandwidth usage information is reported
      bypassing the report-interval if the bandwidth usage report
      condition is met consecutively for the Report-Flow-Count.

   Report-Flow-Count:  This value is used to decide when the bandwidth
      usage collected so far should be reported when there is a sudden
      change in bandwidth usage.  This value indicates how many times
      consecutively, the percentage or absolute difference between the
      current bandwidth sample and the current bandwidth reservation is
      greater than or equal to the Report-Flow-Threshold value, all the
      bandwidth samples collected so far are reported to the PCE
      immediately.

4.2.  Theory of Operation

   The traffic rate is periodically sampled at each sample-interval
   (which can be configured by the user and the default value as 5
   minutes) by the head-end node of the LSP.  The sampled traffic rates
   are accumulated over the adjustment-interval period (which can be
   configured by the user and the default value as 24 hours).  The PCEP
   peer which is in-charge of calculating the bandwidth to be adjusted,
   will adjust the bandwidth of the LSP to the highest sampled traffic
   rate (MaxAvgBw) amongst the set of bandwidth samples collected over
   the adjustment-interval.

   Note that the highest sampled traffic rate could be higher or lower
   than the current LSP bandwidth.  Only if the difference between the
   current bandwidth demand (MaxAvgBw) and the current bandwidth
   reservation is greater than or equal to the Adjustment-Threshold
   (percentage or absolute value), the LSP bandwidth is adjusted to the
   current bandwidth demand (MaxAvgBw).  Some LSPs are less eventful
   while other LSPs may encounter a lot of changes in the traffic
   pattern.  PCE sets the intervals for reporting and adjustment based
   on the traffic pattern of the LSP.

   In order to avoid frequent re-signaling, an operator may set a longer
   adjustment-interval value.  However, longer adjustment-interval can
   result in an undesirable effect of masking sudden changes in traffic
   demands of an LSP.  To avoid this, the Auto-Bandwidth feature may
   pre-maturely expire the adjustment-interval and adjust the LSP
   bandwidth to accommodate the sudden bursts of increase in traffic
   demand as an overflow condition or decrease in traffic demand as an
   underflow condition.

   In case of Deployment model 2, the PCC reports the real-time
   bandwidth-usage information and the PCE decides the adjusted
 


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   bandwidth.  Multiple bandwidth samples are collected every report-
   interval, and reported together to the PCE.  To avoid reporting minor
   changes in real-time bandwidth-usage, report-threshold is used, to
   suppress the sending of the collected samples during the report-
   interval.  The collected samples are reported if at least one sample
   crosses the Report-Threshold (percentage or absolute value).  In
   order to accommodate sudden changes in the bandwidth usage, report-
   flow-threshold is employed by pre-maturely expiry of the report-
   interval to report the unreported bandwidth samples collected so far.

   All thresholds in this document could be represented in both absolute
   value and percentage, and could be used together.

4.3.  Scaling Considerations

   There are potential scaling concerns for the model where PCC (ingress
   LSR) reports real-time bandwidth usage information to the stateful
   PCE for a large number of LSPs.  It is recommended to combine
   multiple bandwidth samples (BwSamples) using larger report-interval
   and report them together to the PCE, thus reducing the number of
   PCRpt messages.  Further, Report-Threshold can be use to skip
   reporting the bandwidth samples for small changes in the bandwidth.

   The processing cost of monitoring a large number of LSPs at the PCC
   and handling bandwidth change requests at PCE should be taken into
   consideration.  Note that, this will be implementation dependent.

5.  Extensions to the PCEP

5.1.  Capability Advertisement

   During PCEP Initialization Phase, PCEP Speakers (PCE or PCC)
   advertise their support of Automatic Bandwidth Adjustment.  A PCEP
   Speaker includes the "Auto-Bandwidth Capability" TLV, in the OPEN
   Object to advertise its support for PCEP Auto-Bandwidth extensions. 
   The presence of the "Auto-Bandwidth Capability" TLV in the OPEN
   Object indicates that the Automatic Bandwidth Adjustment is supported
   as described in this document.  

   The PCEP protocol extensions for Auto-Bandwidth adjustments MUST NOT
   be used if one or both PCEP Speakers have not included the "Auto-
   Bandwidth Capability" TLV in their respective OPEN message.  If the
   PCEP speaker that supports the extensions of this draft but did not
   advertise this capability, then upon receipt of AUTO-BANDWIDTH-
   ATTRIBUTE TLV in LSPA object, it SHOULD generate a PCErr with error-
   type 19 (Invalid Operation), error-value TBD4 (Auto-Bandwidth
   capability was not advertised) and it will terminate the PCEP
   session.
 


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5.1.1 AUTO-BANDWIDTH-CAPABILITY TLV

   The AUTO-BANDWIDTH-CAPABILITY TLV is an optional TLV for use in the
   OPEN Object for Automatic Bandwidth Adjustment via PCEP capability
   advertisement.  Its format is shown in the following figure:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Type=[TBD5]     |            Length=4           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Flags                           |B|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                    AUTO-BANDWIDTH-CAPABILITY TLV format

   The type of the TLV is [TBD5] and it has a fixed length of 4 octets.

   The value comprises a single field - Flags (32 bits):

   o  B (bandwidth usage - 1 bit): if set to 1 by a PCC, the B Flag
      indicates that the PCC allows reporting of bandwidth usage
      information; if set to 1 by a PCE, the B Flag indicates that the
      PCE is capable of receiving bandwidth usage information from the
      PCC.  The BANDWIDTH-USAGE-ATTRIBUTE TLV MUST be encoded when both
      PCEP speakers have the B Flag set.

   Unassigned bits are considered reserved.  They MUST be set to 0 on
   transmission and MUST be ignored on receipt.

   Advertisement of the Auto-Bandwidth capability TLV implies support of
   auto-bandwidth adjustment, as well as the objects, TLVs and
   procedures defined in this document.


5.2.  AUTO-BANDWIDTH-ATTRIBUTE TLV

   The AUTO-BANDWIDTH-ATTRIBUTE TLV provides the 'configurable knobs' of
   the feature and it can be included as an optional TLV in the LSPA
   Object (as described in [RFC5440]).  

   For PCE-Initiated LSP ([I-D.ietf-pce-pce-initiated-lsp]), this TLV is
   included in the LSPA Object with PCInitiate message.  For delegated
   LSPs, this TLV is carried in PCRpt message in LSPA Object.    

   The TLV is encoded in all PCEP messages for the LSP till the auto
   bandwidth adjustment feature is enabled, the absence of the TLV
 


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   indicate the PCEP speaker wish to disable the feature.   

   The format of the AUTO-BANDWIDTH-ATTRIBUTE TLV is shown in the
   following figure:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=[TBD1]         |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   //                            sub-TLVs                          //
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    AUTO-BANDWIDTH-ATTRIBUTE TLV format

   Type: TBD1

   Length: Variable

   Value: This comprises one or more sub-TLVs.

   Following sub-TLVs are defined in this document:

   Type Len Name
   -------------------------------------------------------------------
    1   4   Sample-Interval sub-TLV
    2   4   Adjustment-Interval sub-TLV
    3   4   Adjustment-Threshold sub-TLV
    4   4   Adjustment-Threshold-Percentage sub-TLV
    5   4   Minimum-Bandwidth sub-TLV
    6   4   Maximum-Bandwidth sub-TLV
    7   8   Overflow-Threshold sub-TLV
    8   4   Overflow-Threshold-Percentage sub-TLV
    9   8   Underflow-Threshold sub-TLV
   10   4   Underflow-Threshold-Percentage sub-TLV

   Future specification can define additional sub-TLVs.

   The presence of AUTO-BANDWIDTH-ATTRIBUTE TLV in LSPA Object means
   that the automatic bandwidth adjustment feature is enabled.  All
   sub-TLVs are optional and any unrecognized sub-TLV MUST be silently
   ignored.  If a sub-TLV of same type appears more than once, only the
   first occurrence is processed and all others MUST be ignored.

   The AUTO-BANDWIDTH-ATTRIBUTE TLV can also be carried in PCUpd message
   in LSPA Object in order to make updates to auto-bandwidth attributes
 


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   such as Adjustment-Interval.

   If sub-TLVs are not present, the default values based on the local
   policy are assumed.

   The sub-TLVs are encoded to inform the PCEP peer the various sampling
   and adjustment parameters, and serves the following purpose -

   o  For PCE-Initiated LSPs, in the Deployment Model 1, inform the PCC
      of the various sampling and adjustment parameters.

   o  For PCC-Initiated LSPs, in the Deployment Model 2, inform the PCE
      of the various sampling and adjustment parameters.

   The following sub-sections describe the sub-TLVs which are currently
   defined to be carried within the AUTO-BANDWIDTH-ATTRIBUTE TLV.

5.2.1.  Sample-Interval sub-TLV

   The Sample-Interval sub-TLV specifies a time interval in seconds at
   which traffic samples are collected at the PCC.

   The Type is 1, Length is 4, and the value comprises of 4-octet time
   interval, the valid range is from 1 to 604800, in seconds.  The
   default value is 300 seconds.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=1              |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Sample-Interval                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Sample-Interval sub-TLV format

5.2.2.  Adjustment-Interval sub-TLV

   The Adjustment-Interval sub-TLV specifies a time interval in seconds
   at which bandwidth adjustment should be made.

   The Type is 2, Length is 4, and the value comprises of 4-octet time
   interval, the valid range is from 1 to 604800, in seconds.  The
   default value is 300 seconds.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 


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   |           Type=2              |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Adjustment-Interval                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Adjustment-Interval sub-TLV format

5.2.3.  Adjustment Threshold

   The sub-TLVs in this section are encoded to inform the PCEP peer the
   adjustment threshold parameters.  An implementation MAY include both
   sub-TLVs for the absolute value and the percentage, in which case the
   bandwidth is adjusted when either of the adjustment threshold
   conditions are met.

5.2.3.1.  Adjustment-Threshold sub-TLV

   The Adjustment-Threshold sub-TLV is used to decide when the LSP
   bandwidth should be adjusted.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=3              |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Adjustment Threshold                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Adjustment-Threshold sub-TLV format

   The Type is 3, Length is 4, and the value comprises of -

   o  Adjustment Threshold: The absolute Adjustment-Threshold bandwidth
      value, encoded in IEEE floating point format (see
      [IEEE.754.1985]), expressed in bytes per second.  Refer to Section
      3.1.2 of [RFC3471] for a table of commonly used values.

      If the difference between the current MaxAvgBw and the current
      bandwidth reservation is greater than or equal to the threshold
      value, the LSP bandwidth is adjusted to the current bandwidth
      demand.

5.2.3.2.  Adjustment-Threshold-Percentage sub-TLV

   The Adjustment-Threshold-Percentage sub-TLV is used to decide when
   the LSP bandwidth should be adjusted.

    0                   1                   2                   3
 


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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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=4              |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Reserved                       |  Percentage |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Adjustment-Threshold-Percentage sub-TLV format

   The Type is 4, Length is 4, and the value comprises of -

   o  Reserved: SHOULD be set to zero on transmission and MUST be
      ignored on receipt.

   o  Percentage: The Adjustment-Threshold value, encoded in percentage
      (an integer from 0 to 100).  If the percentage difference between
      the current MaxAvgBw and the current bandwidth reservation is
      greater than or equal to the threshold percentage, the LSP
      bandwidth is adjusted to the current bandwidth demand.

5.2.4.  Minimum and Maximum Bandwidth Values

5.2.4.1.  Minimum-Bandwidth sub-TLV

   The Minimum-Bandwidth sub-TLV specify the minimum bandwidth allowed
   for the LSP, and is expressed in bytes per second.  The LSP bandwidth
   cannot be adjusted below the minimum bandwidth value.

   The Type is 5, Length is 4, and the value comprises of 4-octet
   bandwidth value encoded in IEEE floating point format (see
   [IEEE.754.1985]), expressed in bytes per second.  Refer to Section
   3.1.2 of [RFC3471] for a table of commonly used values.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=5              |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Minimum-Bandwidth                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Minimum-Bandwidth sub-TLV format

5.2.4.2.  Maximum-Bandwidth sub-TLV

   The Maximum-Bandwidth sub-TLV specify the maximum bandwidth allowed
   for the LSP, and is expressed in bytes per second.  The LSP bandwidth
   cannot be adjusted above the maximum bandwidth value.
 


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   The Type is 6, Length is 4, and the value comprises of 4-octet
   bandwidth value encoded in IEEE floating point format (see
   [IEEE.754.1985]), expressed in bytes per second.  Refer to Section
   3.1.2 of [RFC3471] for a table of commonly used values.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=6              |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Maximum-Bandwidth                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Maximum-Bandwidth sub-TLV format

5.2.5.  Overflow and Underflow Condition

   The sub-TLVs in this section are encoded to inform the PCEP peer the
   overflow and underflow threshold parameters.  An implementation MAY
   include sub-TLVs for the absolute value and the percentage for the
   threshold, in which case the bandwidth is immediately adjusted when
   either of the adjustment threshold conditions are met consecutively
   for the given count.

5.2.5.1.  Overflow-Threshold sub-TLV

   The Overflow-Threshold sub-TLV is used to decide if the bandwidth
   should be adjusted immediately.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=7              |           Length=8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Reserved                     |      Count    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Overflow Threshold                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Overflow-Threshold sub-TLV format

   The Type is 7, Length is 8, and the value comprises of -

   o  Reserved: SHOULD be set to zero on transmission and MUST be
      ignored on receipt.

   o  Count: The Overflow-Count value, encoded in integer.  The value 0
      is considered to be invalid.  The number of consecutive samples
 


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      for which the overflow condition MUST be met for the LSP bandwidth
      to be immediately adjusted to the current bandwidth demand,
      bypassing the adjustment-interval.

   o  Overflow Threshold: The absolute Overflow-Threshold bandwidth
      value, encoded in IEEE floating point format (see
      [IEEE.754.1985]), expressed in bytes per second.  Refer to Section
      3.1.2 of [RFC3471] for a table of commonly used values. If the
      increase of the current MaxAvgBw from the current bandwidth
      reservation is greater than or equal to the threshold value, the
      overflow condition is met.

5.2.5.2.  Overflow-Threshold-Percentage sub-TLV

   The Overflow-Threshold-Percentage sub-TLV is used to decide if the
   bandwidth should be adjusted immediately.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=8              |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Percentage |    Reserved                     |      Count    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Overflow-Threshold-Percentage sub-TLV format

   The Type is 8, Length is 4, and the value comprises of -

   o  Percentage: The Overflow-Threshold value, encoded in percentage
      (an integer from 0 to 100).  If the percentage increase of the
      current MaxAvgBw from the current bandwidth reservation is greater
      than or equal to the threshold percentage, the overflow condition
      is met.

   o  Reserved: SHOULD be set to zero on transmission and MUST be
      ignored on receipt.

   o  Count: The Overflow-Count value, encoded in integer.  The value 0
      is considered to be invalid.  The number of consecutive samples
      for which the overflow condition MUST be met for the LSP bandwidth
      to be immediately adjusted to the current bandwidth demand,
      bypassing the adjustment-interval.

5.2.5.3.  Underflow-Threshold sub-TLV

   The Underflow-Threshold sub-TLV is used to decide if the bandwidth
   should be adjusted immediately.
 


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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=9              |           Length=8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Reserved                     |      Count    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Underflow Threshold                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Underflow-Threshold sub-TLV format

   The Type is 9, Length is 8, and the value comprises of -

   o  Reserved: SHOULD be set to zero on transmission and MUST be
      ignored on receipt.

   o  Count: The Underflow-Count value, encoded in integer.  The value 0
      is considered to be invalid.  The number of consecutive samples
      for which the underflow condition MUST be met for the LSP
      bandwidth to be immediately adjusted to the current bandwidth
      demand, bypassing the adjustment-interval.

   o  Underflow Threshold: The absolute Underflow-Threshold bandwidth
      value, encoded in IEEE floating point format (see
      [IEEE.754.1985]), expressed in bytes per second.  Refer to Section
      3.1.2 of [RFC3471] for a table of commonly used values.  If the
      decrease of the current MaxAvgBw from the current bandwidth
      reservation is greater than or equal to the threshold value, the
      underflow condition is met.

5.2.5.4.  Underflow-Threshold-Percentage sub-TLV

   The Underflow-Threshold-Percentage sub-TLV is used to decide if the
   bandwidth should be adjusted immediately.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=10             |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Percentage |    Reserved                     |      Count    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Underflow-Threshold-Percentage sub-TLV format

   The Type is 10, Length is 4, and the value comprises of -

 


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   o  Percentage: The Underflow-Threshold value, encoded in percentage
      (an integer from 0 to 100).  If the percentage decrease of the
      current MaxAvgBw from the current bandwidth reservation is greater
      than or equal to the threshold percentage, the underflow condition
      is met.

   o  Reserved: SHOULD be set to zero on transmission and MUST be
      ignored on receipt.

   o  Count: The Underflow-Count value, encoded in integer.  The value 0
      is considered to be invalid.  The number of consecutive samples
      for which the underflow condition MUST be met for the LSP
      bandwidth to be immediately adjusted to the current bandwidth
      demand, bypassing the adjustment-interval.

5.3.  BANDWIDTH-USAGE-ATTRIBUTE TLV

   The BANDWIDTH-USAGE-ATTRIBUTE TLV provides the 'configurable knobs'
   of the feature and it can be included as an optional TLV in the LSPA
   Object (as described in [RFC5440]).  

   For PCE-Initiated LSP ([I-D.ietf-pce-pce-initiated-lsp]), this TLV is
   included in the LSPA Object with PCInitiate message.     

   The TLV is encoded in all PCEP messages for the LSP till the
   bandwidth usage reporting feature is enabled, the absence of the TLV
   indicate the PCEP speaker wish to disable this feature.   

   The format of the BANDWIDTH-USAGE-ATTRIBUTE TLV is shown in the
   following figure:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=[TBD2]         |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   //                            sub-TLVs                          //
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    BANDWIDTH-USAGE-ATTRIBUTE TLV format

   Type: TBD2

   Length: Variable

   Value: This comprises one or more sub-TLVs.
 


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   Following sub-TLVs are defined in this document:

   Type Len Name
   -------------------------------------------------------------------
   1    4   Bandwidth-Usage-Report-Interval sub-TLV
   2    4   Bandwidth-Usage-Report-Threshold sub-TLV
   3    4   Bandwidth-Usage-Report-Threshold-Percentage sub-TLV
   4    4   Bandwidth-Usage-Report-Flow-Threshold sub-TLV
   5    4   Bandwidth-Usage-Report-Flow-Threshold-Percentage sub-TLV

   Future specification can define additional sub-TLVs.

   The presence of BANDWIDTH-USAGE-ATTRIBUTE TLV in LSPA Object means
   that the  bandwidth usage reporting to PCE is enabled.  All sub-TLVs
   are optional and any unrecognized sub-TLV MUST be silently ignored. 
   If a sub-TLV of same type appears more than once, only the first
   occurrence is processed and all others MUST be ignored.

   The BANDWIDTH-USAGE-ATTRIBUTE TLV can also be carried in PCUpd
   message in LSPA Object in order to make updates to the attributes
   such as Bandwidth-Usage-Report-Interval.

   If sub-TLVs are not present, the default values based on the local
   policy are assumed.

   The following sub-sections describe the sub-TLVs which are currently
   defined to be carried within the BANDWIDTH-USAGE-ATTRIBUTE TLV, and
   serves the following purpose -

   o  For PCE-Initiated LSPs, in the Deployment Model 2, inform the PCC
      of the various sampling and reporting parameters.


5.3.1.  Bandwidth-Usage-Report-Interval sub-TLV

      The Bandwidth-Usage-Report-Interval sub-TLV specifies a time
      interval in seconds in which collected bandwidth samples should be
      reported to PCE.

      The Type is 1, Length is 4, and the value comprises of 4-octet
      time interval, the valid range is from 1 to 604800, in seconds. 
      Default value is 3600 seconds.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Type=1              |           Length=4            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 


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      |              Bandwidth-Usage-Report-Interval                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Bandwidth-Usage-Report-Interval sub-TLV format


5.3.2.  Bandwidth-Usage-Report-Threshold sub-TLV

      The Bandwidth-Usage-Report-Threshold sub-TLV is used to decide
      when the bandwidth samples collected so far should be reported
      immediately, bypassing the report-interval.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Type=2              |           Length=4            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              Bandwidth-Usage-Report Threshold                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Bandwidth-Usage-Report-Threshold sub-TLV format

      The Type is 2, Length is 4, and the value comprises of -

   o  Threshold: The absolute threshold bandwidth value, encoded in IEEE
      floating point format (see [IEEE.754.1985]), expressed in bytes
      per second.  Refer to Section 3.1.2 of [RFC3471] for a table of
      commonly used values.  If the increase or the decrease of at least
      one of the bandwidth samples (BwSamples) collected so far compared
      to the current bandwidth reservation is greater than or equal to
      the threshold value, the bandwidth samples collected so far are
      reported.

5.3.3.  Bandwidth-Usage-Report-Threshold-Percentage sub-TLV

   The Bandwidth-Usage-Report-Threshold-Percentage sub-TLV is used to
   decide when the bandwidth samples collected so far should be reported
   immediately, bypassing the report-interval.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=3              |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Reserved                       |  Percentage |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Bandwidth-Usage-Report-Threshold-Percentage sub-TLV format
 


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   The Type is 3, Length is 4, and the value comprises of -

   o  Reserved: SHOULD be set to zero on transmission and MUST be
      ignored on receipt.

   o  Percentage: The threshold value, encoded in percentage (an integer
      from 0 to 100).  If the percentage increase or the decrease of at
      least one of the bandwidth sample (BwSample) compared to the
      current bandwidth reservation is greater than or equal to the
      threshold percentage, the bandwidth samples collected so far are
      reported.

5.3.4.  Bandwidth-Usage-Report-Flow-Threshold sub-TLV

   The Bandwidth-Usage-Report-Flow-Threshold sub-TLV is used to decide
   when the bandwidth samples collected should be reported immediately,
   bypassing the report-interval.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=4              |           Length=8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Reserved                     |      Count    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Bandwidth-Usage-Report-Flow Threshold               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Bandwidth-Usage-Report-Flow-Threshold sub-TLV format

   The Type is 4, Length is 8, and the value comprises of -

   o  Reserved: SHOULD be set to zero on transmission and MUST be
      ignored on receipt.

   o  Count: The Report-Flow-Count value, encoded in integer.  The value
      0 is considered to be invalid.  The number of consecutive samples
      for which the bandwidth usage report condition MUST be met for the
      the bandwidth samples collected so far are reported immediately,
      bypassing the report-interval.

   o  Threshold: The absolute flow threshold bandwidth value, encoded in
      IEEE floating point format (see [IEEE.754.1985]), expressed in
      bytes per second.  Refer to Section 3.1.2 of [RFC3471] for a table
      of commonly used values.  If the increase or the decrease of the
      current bandwidth sample (BwSample) compared to the current
      bandwidth reservation is greater than or equal to the flow
      threshold value, bandwidth usage report condition is said to be
 


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      met.

5.3.5.  Bandwidth-Usage-Report-Flow-Threshold-Percent sub-TLV

   The Bandwidth-Usage-Report-Flow-Threshold-Percent sub-TLV is used to
   decide when the bandwidth samples collected should be reported
   immediately, bypassing the report-interval.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type=5              |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Percentage |    Reserved                     |      Count    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Bandwidth-Usage-Report-Flow-Threshold-Percentage sub-TLV format

   The Type is 5, Length is 4, and the value comprises of -

   o  Reserved: SHOULD be set to zero on transmission and MUST be
      ignored on receipt.

   o  Percentage: The flow threshold value, encoded in percentage (an
      integer from 0 to 100).  If the percentage increase or the
      decrease of the current bandwidth sample (BwSample) compared to
      the current bandwidth reservation is greater than or equal to the
      threshold percentage, bandwidth usage report condition is said to
      be met.

   o  Count: The Report-Flow-Count value, encoded in integer.  The value
      0 is considered to be invalid.  The number of consecutive samples
      for which the bandwidth usage report condition MUST be met for the
      the bandwidth samples collected so far are reported immediately,
      bypassing the report-interval. 

5.4.  BANDWIDTH Object

5.4.1.  Auto-Bandwidth Adjusted Bandwidth Report

   As per [RFC5440], the BANDWIDTH object (Object-Class value 5) is
   defined with two Object-Type values as following:

   o  Requested Bandwidth: BANDWIDTH Object-Type value is 1.

   o  Re-optimization Bandwidth: Bandwidth of an existing TE LSP for
      which a re-optimization is requested.  BANDWIDTH Object-Type value
      is 2.
 


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   In the first deployment model, where PCC calculates the adjusted
   bandwidth, PCC reports the calculated bandwidth to be adjusted
   (MaxAvgBw) to the PCE.  This is done via the existing 'Requested
   Bandwidth with BANDWIDTH Object-Type as 1.

5.4.2.  Bandwidth-Usage Report

   A new Object-type for BANDWIDTH object is defined to report the real-
   time bandwidth usage of a TE LSP.

   The Object-type is [TBD3], the object length is variable with
   multiples of 4 bytes.  The payload format is 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        BwSample1                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           ...                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        BwSampleN                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          Bandwidth-Usage format

   o  BwSample: The actual bandwidth usage, (the BwSample collected at
      the end of each sample-interval) encoded in IEEE floating point
      format (see [IEEE.754.1985]), expressed in bytes per second.

   The Bandwidth-Usage object-type is used in the second deployment
   model where PCC reports the TE LSP bandwidth usage and the PCE
   decides the Auto-Bandwidth adjusted bandwidth.

   The Bandwidth-Usage object-type can also be used for TE LSPs without
   enabling the Auto-Bandwidth feature, to learn the actual bandwidth
   usage of the LSPs for other applications at the stateful PCE, details
   of which are beyond the scope of this document.


5.5.  The PCInitiate Message

   A PCInitiate message is a PCEP message sent by a PCE to a PCC to
   trigger LSP instantiation or deletion [I.D.ietf-pce-pce-initiated-
   lsp].

   For the PCE-initiated LSP [I-D.ietf-pce-pce-initiated-lsp] with
   Auto-Bandwidth feature enabled, AUTO-BANDWIDTH-ATTRIBUTE TLV or
   BANDWIDTH-USAGE-ATTRIBUTE TLV MUST be included in the LSPA object
 


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   with the PCInitiate message, depending on the deployment model being
   used.  The rest of the processing remains unchanged.


5.6.  The PCRpt Message

   As specified in [I.D.ietf-pce-pce-initiated-lsp], the PCC creates the
   LSP using the attributes communicated by the PCE, and local values
   for the unspecified parameters.  After the successful instantiation
   of the LSP, PCC automatically delegates the LSP to the PCE and
   generates an LSP State Report (PCRpt) for the LSP.

   When LSP is delegated to a PCE for the very first time, BANDWIDTH
   object of type 1 is used to specify the requested bandwidth in the
   PCRpt message.

   When the LSP is enabled with the Auto-Bandwidth feature using
   Deployment Model 1, PCC SHOULD include the BANDWIDTH object of type 1
   to specify the calculated bandwidth to be adjusted to the PCE in the
   PCRpt message.

   When the LSP is enabled with the Auto-Bandwidth feature using
   Deployment Model 2, PCC SHOULD include the BANDWIDTH object of type
   [TBD3] to report the real-time bandwidth-usage to the PCE in the
   PCRpt message.

   The definition of the PCRpt message (see [I-D.ietf-pce-stateful-pce])
   is unchanged by this document.


6.  Security Considerations

   This document defines a new BANDWIDTH object type,
   AUTO-BANDWIDTH-CAPABILITY TLV, AUTO-BANDWIDTH-ATTRIBUTE TLV and
   BANDWIDTH-USAGE-ATTRIBUTE TLV which do not add any new security
   concerns beyond those discussed in [RFC5440] and
   [I-D.ietf-pce-stateful-pce].

   Some deployments may find the reporting of the real-time bandwidth-
   usage information as extra sensitive and thus SHOULD employ suitable
   PCEP security mechanisms like TCP-AO or [I-D.ietf-pce-pceps].

7.  Manageability Considerations

7.1.  Control of Function and Policy

   The Auto-Bandwidth feature SHOULD be controlled per tunnel (at
   ingress (PCC) or PCE), the values for parameters like sample-
 


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   interval, adjustment-interval, minimum-bandwidth, maximum-bandwidth,
   adjustment-threshold, report-interval, report-threshold SHOULD be
   configurable by an operator.

7.2.  Information and Data Models

   [RFC7420] describes the PCEP MIB, there are no new MIB Objects
   defined in this document.

7.3.  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].

7.4.  Verify Correct Operations

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

7.5.  Requirements On Other Protocols

   Mechanisms defined in this document do not add any new requirements
   on other protocols.

7.6.  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].


















 


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8.  IANA Considerations

8.1.  PCEP TLV Type Indicators

   This document defines the following new PCEP TLVs; IANA is requested
   to make the following allocations from this registry. 
   <http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type-
   indicators>.

   Value   Name                                       Reference
   --------------------------------------------------------------
   TBD5    AUTO-BANDWIDTH-CAPABILITY                  [This I.D.]
   TBD1    AUTO-BANDWIDTH-ATTRIBUTE                   [This I.D.]
   TBD2    BANDWIDTH-USAGE-ATTRIBUTE                  [This I.D.]

8.2.  AUTO-BANDWIDTH-ATTRIBUTE Sub-TLV

   This document specifies the AUTO-BANDWIDTH-ATTRIBUTE Sub-TLVs.  IANA
   is requested to create an "AUTO-BANDWIDTH-ATTRIBUTE Sub-TLV Types"
   sub-registry in the "PCEP TLV Type Indicators" for the sub-TLVs
   carried in the AUTO-BANDWIDTH-ATTRIBUTE TLV.  This document defines
   the following types:

   Type Name                                          Reference
   --------------------------------------------------------------
    0   Reserved                                      [This I.D.]
    1   Sample-Interval sub-TLV                       [This I.D.]
    2   Adjustment-Interval sub-TLV                   [This I.D.]
    3   Adjustment-Threshold sub-TLV                  [This I.D.]
    4   Adjustment-Threshold-Percentage sub-TLV       [This I.D.]
    5   Minimum-Bandwidth sub-TLV                     [This I.D.]
    6   Maximum-Bandwidth sub-TLV                     [This I.D.]
    7   Overflow-Threshold sub-TLV                    [This I.D.]
    8   Overflow-Threshold-Percentage sub-TLV         [This I.D.]
    9   Underflow-Threshold sub-TLV                   [This I.D.]
   10   Underflow-Threshold-Percentage sub-TLV        [This I.D.]
   11-  Unassigned                                    [This I.D.]
   65535

8.3.  BANDWIDTH-USAGE-ATTRIBUTE Sub-TLV

   This document specifies the BANDWIDTH-USAGE-ATTRIBUTE Sub-TLVs.  IANA
   is requested to create an "BANDWIDTH-USAGE-ATTRIBUTE Sub-TLV Types"
   sub-registry in the "PCEP TLV Type Indicators" for the sub-TLVs
   carried in the BANDWIDTH-USAGE-ATTRIBUTE TLV.  This document defines
   the following types:


 


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   Type Name                                          Reference
   --------------------------------------------------------------
    0   Reserved                                      [This I.D.]
    1   Bandwidth-Usage-Report-Interval sub-TLV       [This I.D.]
    2   Bandwidth-Usage-Report-Threshold sub-TLV      [This I.D.]
    3   Bandwidth-Usage-Report-Threshold-Percentage   [This I.D.]
        sub-TLV
    4   Bandwidth-Usage-Report-Flow-Threshold         [This I.D.]
        sub-TLV
    5   Bandwidth-Usage-Report-Flow-Threshold         [This I.D.]
        -Percentage sub-TLV
    6-  Unassigned                                    [This I.D.]
   65535


8.4.  BANDWIDTH Object

   This document defines new Object-Type for the BANDWIDTH object
   (Object-Class 5, [RFC5440]); IANA is requested to make the following
   allocation from this registry.
   <http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-objects>.

   Object-Type Name                                    Reference
   --------------------------------------------------------------
    TBD3       Bandwidth-Usage Report                  [This I.D.]


8.5.  Error Object

   This document defines a new Error-Value for PCErr message of type 19
   (Invalid Operation) [I-D.ietf-pce-stateful-pce]); IANA is requested
   to make the following allocation from this registry.
   <http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-error-object>

   Error-Value Meaning                                 Reference
   --------------------------------------------------------------
    TBD4       Auto-Bandwidth Capability               [This I.D.]
               was not Advertised



9.  References

9.1.  Normative References

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

 


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

   [I-D.ietf-pce-stateful-pce]  Crabbe, E., Minei, I., Medved, J., and
              R. Varga, "PCEP Extensions for Stateful PCE", draft-ietf-
              pce-stateful-pce (work in progress).

   [I-D.ietf-pce-pce-initiated-lsp]  Crabbe, E., Minei, I., Sivabalan,
              S., and R. Varga, "PCEP Extensions for PCE-initiated LSP
              Setup in a Stateful PCE Model", draft-ietf-pce-pce-
              initiated-lsp (work in progress).

   [IEEE.754.1985]  Institute of Electrical and Electronics Engineers,
              "Standard for Binary Floating-Point Arithmetic", IEEE
              Standard 754, August 1985.


9.2.  Informative References

   [RFC3471]  Berger, L., "Generalized Multi-Protocol Label Switching
              (GMPLS) Signaling Functional Description", RFC 3471,
              January 2003.

   [RFC7420]  Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
              Hardwick, "Path Computation Element Communication Protocol
              (PCEP) Management Information Base (MIB) Module", RFC
              7420, December 2014.

   [I-D.ietf-pce-stateful-pce-app]  Zhang, X. and I. Minei,
              "Applicability of a Stateful Path Computation Element
              (PCE)", draft-ietf-pce-stateful-pce-app (work in
              progress).

   [I-D.ietf-pce-pceps]  Lopez, D., Dios, O., Wu, W., and D. Dhody,
              "Secure Transport for PCEP", draft-ietf-pce-pceps (work in
              progress).











 


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Acknowledgments

   Authors would like to thank Robert Varga, Venugopal Reddy, Reeja
   Paul, Sandeep Boina and Avantika for their useful comments and
   suggestions.


Contributors' Addresses

   He Zekun
   Tencent Holdings Ltd,
   Shenzhen P.R.China

   EMail: kinghe@tencent.com


   Xian Zhang
   Huawei Technologies
   Research Area F3-1B,
   Huawei Industrial Base,
   Shenzhen, 518129
   China

   Phone: +86-755-28972645
   EMail: zhang.xian@huawei.com


   Young Lee
   Huawei Technologies
   1700 Alma Drive, Suite 100
   Plano, TX  75075
   USA

   Phone: +1 972 509 5599 x2240
   Fax:   +1 469 229 5397
   EMail: leeyoung@huawei.com












 


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Authors' Addresses

   Dhruv Dhody
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: dhruv.ietf@gmail.com


   Udayasree Palle
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560037
   India

   EMail: udayasree.palle@huawei.com


   Ravi Singh
   Juniper Networks
   1194 N. Mathilda Ave.
   Sunnyvale, CA  94089
   USA

   EMail: ravis@juniper.net


   Rakesh Gandhi
   Cisco Systems, Inc.

   EMail: rgandhi.ietf@gmail.com


   Luyuan Fang
   Microsoft
   15590 NE 31st St
   Redmond, WA  98052
   USA

   EMail: lufang@microsoft.com









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