[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits] [IPR]

Versions: (draft-dhody-pce-stateful-pce-auto-bandwidth) 00 01 02 03 04 05 06 07

PCE Working Group                                               D. Dhody
Internet-Draft                                                  U. Palle
Intended status: Standards Track                     Huawei Technologies
Expires: November 22, 2018                                      R. Singh
                                                        Juniper Networks
                                                               R. Gandhi
                                                     Cisco Systems, Inc.
                                                                 L. Fang
                                                           Expedia, Inc.
                                                            May 21, 2018


  PCEP Extensions for MPLS-TE LSP Automatic Bandwidth Adjustment with
                              Stateful PCE
              draft-ietf-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.

   Automatic bandwidth allows automatic and dynamic adjustment of the TE
   LSP bandwidth reservation based on the volume of traffic flowing
   through the LSP.  This document describes PCEP extensions for
   automatic bandwidth adjustment when employing an Active Stateful PCE
   for both PCE-Initiated and PCC-Initiated LSPs.


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





Dhody, et al.          Expires November 22, 2018                [Page 1]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


Copyright Notice

   Copyright (c) 2018 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.




Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  4
     2.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  4
     2.2.  Abbreviations  . . . . . . . . . . . . . . . . . . . . . .  4
     2.3.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Requirements for PCEP Extensions . . . . . . . . . . . . . . .  7
   4.  Architectural Overview . . . . . . . . . . . . . . . . . . . .  8
     4.1.  Auto-Bandwidth Overview  . . . . . . . . . . . . . . . . .  8
     4.2.  Auto-bandwidth Theory of Operation . . . . . . . . . . . .  8
     4.3.  Scaling Considerations . . . . . . . . . . . . . . . . . . 10
   5.  Extensions to the PCEP . . . . . . . . . . . . . . . . . . . . 10
     5.1.  Capability Advertisement . . . . . . . . . . . . . . . . . 10
       5.1.1.  AUTO-BANDWIDTH-CAPABILITY TLV  . . . . . . . . . . . . 10
     5.2.  AUTO-BANDWIDTH-ATTRIBUTES TLV  . . . . . . . . . . . . . . 11
       5.2.1.  Sample-Interval sub-TLV  . . . . . . . . . . . . . . . 13
       5.2.2.  Adjustment Intervals . . . . . . . . . . . . . . . . . 13
         5.2.2.1.  Adjustment-Interval sub-TLV  . . . . . . . . . . . 13
         5.2.2.2.  Down-Adjustment-Interval sub-TLV . . . . . . . . . 14
       5.2.3.  Adjustment Thresholds  . . . . . . . . . . . . . . . . 14
         5.2.3.1.  Adjustment-Threshold sub-TLV . . . . . . . . . . . 15
         5.2.3.2.  Adjustment-Threshold-Percentage sub-TLV  . . . . . 15
         5.2.3.3.  Down-Adjustment-Threshold sub-TLV  . . . . . . . . 16
         5.2.3.4.  Down-Adjustment-Threshold-Percentage sub-TLV . . . 17
       5.2.4.  Minimum and Maximum Bandwidth Values . . . . . . . . . 17
         5.2.4.1.  Minimum-Bandwidth sub-TLV  . . . . . . . . . . . . 17
         5.2.4.2.  Maximum-Bandwidth sub-TLV  . . . . . . . . . . . . 18
       5.2.5.  Overflow and Underflow Conditions  . . . . . . . . . . 18
         5.2.5.1.  Overflow-Threshold sub-TLV . . . . . . . . . . . . 19



Dhody, et al.          Expires November 22, 2018                [Page 2]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


         5.2.5.2.  Overflow-Threshold-Percentage sub-TLV  . . . . . . 19
         5.2.5.3.  Underflow-Threshold sub-TLV  . . . . . . . . . . . 20
         5.2.5.4.  Underflow-Threshold-Percentage sub-TLV . . . . . . 21
     5.3.  BANDWIDTH Object . . . . . . . . . . . . . . . . . . . . . 22
     5.4.  The PCInitiate Message . . . . . . . . . . . . . . . . . . 22
     5.5.  The PCUpd Message  . . . . . . . . . . . . . . . . . . . . 22
     5.6.  The PCRpt Message  . . . . . . . . . . . . . . . . . . . . 23
     5.7.  The PCNtf Message  . . . . . . . . . . . . . . . . . . . . 23
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 24
   7.  Manageability Considerations . . . . . . . . . . . . . . . . . 24
     7.1.  Control of Function and Policy . . . . . . . . . . . . . . 24
     7.2.  Information and Data Models  . . . . . . . . . . . . . . . 24
     7.3.  Liveness Detection and Monitoring  . . . . . . . . . . . . 25
     7.4.  Verify Correct Operations  . . . . . . . . . . . . . . . . 25
     7.5.  Requirements On Other Protocols  . . . . . . . . . . . . . 25
     7.6.  Impact On Network Operations . . . . . . . . . . . . . . . 25
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 26
     8.1.  PCEP TLV Type Indicators . . . . . . . . . . . . . . . . . 26
     8.2.  AUTO-BANDWIDTH-CAPABILITY TLV Flag Field . . . . . . . . . 26
     8.3.  AUTO-BANDWIDTH-ATTRIBUTES Sub-TLV  . . . . . . . . . . . . 26
     8.4.  Error Object . . . . . . . . . . . . . . . . . . . . . . . 27
     8.5.  Notification Object  . . . . . . . . . . . . . . . . . . . 27
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 28
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 28
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 28
   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . . . 30
   Contributors' Addresses  . . . . . . . . . . . . . . . . . . . . . 30
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31






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).

   [RFC8231] 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.  Further, [RFC8281] describes the setup,
   maintenance and teardown of PCE-Initiated LSPs for the stateful PCE
   model.  In this document, the focus is on Active stateful PCE where
   the LSPs are controlled by the PCE.



Dhody, et al.          Expires November 22, 2018                [Page 3]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   Over time, based on the varying traffic pattern, an LSP established
   with a certain bandwidth may require to adjust the bandwidth reserved
   in the network dynamically.  The head-end Label Switch Router (LSR)
   monitors the actual bandwidth demand of the established LSP and
   periodically computes new bandwidth.  The head-end LSR adjusts the
   bandwidth reservation of the LSP based on the computed bandwidth
   automatically.  This feature is commonly referred to as Auto-
   Bandwidth.  The Auto-Bandwidth feature is described in detail in
   Section 4 of this document.

   In the model considered in this document, the PCC (head-end of the
   LSP) collects the traffic rate samples flowing through the LSP and
   calculates the new adjusted bandwidth.  The PCC reports the
   calculated bandwidth to be adjusted to the PCE.  This is similar to
   the Passive stateful PCE model, while the Passive stateful PCE uses
   path request/reply mechanism, the Active stateful PCE uses
   report/update mechanism.  In case of PCE-Initiated LSP, the PCC is
   requested during the LSP initiation to monitor and calculate the new
   adjusted bandwidth.  [RFC8051] describes the use-case for Auto-
   Bandwidth adjustment for Passive and Active stateful PCE.

   This document defines the PCEP extensions needed to support Auto-
   Bandwidth feature in a Active stateful PCE model where the LSP
   bandwidth to be adjusted is calculated on the PCC (head-end of the
   LSP). The use of PCE to calculate the bandwidth to be adjusted is out
   of scope of this document.


2.  Conventions Used in This Document

2.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.2.  Abbreviations

   PCC:  Path Computation Client.

   PCE:  Path Computation Element.

   PCEP:  Path Computation Element Communication Protocol.

   TE LSP:  Traffic Engineering Label Switched Path.




Dhody, et al.          Expires November 22, 2018                [Page 4]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


2.3.  Terminology

   The reader is assumed to be familiar with the terminology defined in
   [RFC5440], [RFC8231], and [RFC8281].

   The following auto-bandwidth terminology is defined in this document.

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

   Adjusted Bandwidth:  This is the Auto-Bandwidth computed bandwidth
      that is used to adjust the bandwidth reservation of the LSP.

   Sample-Interval:  The periodic time interval at which the measured
      traffic rate of the LSP is collected as a Bandwidth-Sample.

   Bandwidth-Sample:  The bandwidth sample of the measured traffic rate
      of the LSP collected at every Sample-Interval.

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

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

   Up-Adjustment-Interval:  The periodic time interval at which the
      bandwidth adjustment should be made using the MaxAvgBw, when
      MaxAvgBw is greater than the current bandwidth reservation of the
      LSP.

   Down-Adjustment-Interval:  The periodic time interval at which the
      bandwidth adjustment should be made using the MaxAvgBw, when
      MaxAvgBw is lesser than the current bandwidth reservation of the
      LSP.

   Up-Adjustment-Threshold:  This parameter is used to decide when the
      LSP 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 (upsized) to the current bandwidth
      demand (Adjusted Bandwidth) at the Up-Adjustment-Interval expiry.

   Down-Adjustment-Threshold:  This parameter is used to decide when the
      LSP bandwidth should be adjusted.  If the percentage or absolute
      difference between the current bandwidth reservation and the



Dhody, et al.          Expires November 22, 2018                [Page 5]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


      current MaxAvgBw is greater than or equal to the threshold value,
      the LSP bandwidth is adjusted (downsized) to the current bandwidth
      demand (Adjusted Bandwidth) at the Down-Adjustment-Interval
      expiry.

   Overflow-Count:  This parameter is used to decide when the LSP
      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 of the LSP
      is greater than or equal to the Overflow-Threshold value.

   Overflow-Threshold:  This parameter is used to decide when the LSP
      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 of the
      LSP 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 Up-Adjustment-Interval if
      the overflow condition is met consecutively for the Overflow-
      Count.

   Underflow-Count:  This parameter is used to decide when the LSP
      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 of the LSP
      is greater than or equal to the Underflow-Threshold value.

   Underflow-Threshold:  This parameter is used to decide when the LSP
      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 of the
      LSP 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 Down-Adjustment-Interval if
      the underflow condition is met consecutively for the Underflow-
      Count.

   Minimum-Threshold:  The increase or decrease of the LSP bandwidth
      should be at least or above the minimum-threshold represented as
      an absolute bandwidth value before the bandwidth adjustment for
      the LSP is made.  This threshold can be seen as a suppression
      threshold that is used along with a percentage threshold to avoid
      unnecessary auto-bandwidth adjustments and re-signaling of the LSP
      at low bandwidth values.





Dhody, et al.          Expires November 22, 2018                [Page 6]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


3.  Requirements for PCEP Extensions

   The PCEP extensions required for auto-bandwidth are summarized in the
   following table as well as in Figure 1.

   +---------------------------------+---------------------------------+
   | 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.            |
   |                                 |                                 |
   | Extension is needed for PCC     | Extension is needed for PCE     |
   | to pass on the adjustment       | to pass on the adjustment       |
   | parameters at the time of       | parameters at the time of       |
   | LSP Delegation.                 | LSP Initiation.                 |
   |                                 |                                 |
   +---------------------------------+---------------------------------+

       Table 1: Requirements for Auto-Bandwidth PCEP extensions

                             ----------
                            |          |
                            |   PCE    |
                            |          |
                             ----------
                               |    ^
    AUTO-BANDWIDTH CAPABILITY  |    |  AUTO-BANDWIDTH CAPABILITY
                               |    |
    AUTO-BANDWIDTH ATTRIBUTES  |    |  AUTO-BANDWIDTH ATTRIBUTES
                               |    |  (For Delegated LSPs)
                               |    |
                               |    |  REQUESTED BANDWIDTH
                               v    |
                             ----------
                            |          |
                            |   PCC    |
                            |          |
                             ----------

        Figure 1: Overview of Auto-Bandwidth PCEP extensions


   The PCEP speaker supporting this document must have a mechanism to
   advertise the automatic bandwidth adjustment capability for both PCC-



Dhody, et al.          Expires November 22, 2018                [Page 7]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   Initiated and PCE-Initiated LSPs.

   Auto-bandwidth deployment considerations for PCEP extensions are
   summarized below:

   o  It is required to identify and inform the PCC, 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  In addition, an operator should be able to specify the auto-
      bandwidth adjustment parameters (i.e. configuration knobs) to
      control this feature (e.g. minimum/ maximum bandwidth range).  The
      PCC should be informed about these adjustment parameters.


4.  Architectural Overview

4.1.  Auto-Bandwidth Overview

   Auto-Bandwidth feature allows automatic and dynamic adjustment of the
   reserved bandwidth of an LSP over time, i.e. without network operator
   intervention to accommodate the varying traffic demand of the LSP.
   If the traffic flowing through the LSP is lower than the configured
   or current reserved 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 reserved bandwidth of the LSP, it can potentially cause
   congestion or packet loss in the network.  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.  The
   head-end Label Switch Router (LSR) monitors the actual traffic
   flowing through the LSP and uses that information to adjust the
   bandwidth reservation of the LSP in the network.  The bandwidth
   adjustment uses the make-before-break (MBB) signaling method so that
   there is no disruption to the traffic flow carried by the LSP.

4.2.  Auto-bandwidth Theory of Operation

   When the Auto-Bandwidth feature is enabled, the measured traffic rate
   is periodically sampled at each Sample-Interval (which can be
   configured by an operator and the default value as 5 minutes) by the
   PCC which is the head-end node of the LSP.  The traffic rate samples
   are accumulated over the Adjustment-Interval period (which can be
   configured by an operator and the default value as 24 hours).  The
   PCC, in-charge of calculating the bandwidth to be adjusted, will
   adjust the bandwidth of the LSP to the highest traffic rate sample
   (MaxAvgBw) amongst the set of bandwidth samples collected over the



Dhody, et al.          Expires November 22, 2018                [Page 8]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   adjustment-interval period (in the Up or Down direction).

   Note that the highest traffic rate sample 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) (which can be configured by an
   operator and the default as 5 percentage), the LSP bandwidth is
   adjusted (upsized) to the current bandwidth demand (MaxAvgBw).
   Similarly, if the difference between the current bandwidth
   reservation and the current bandwidth demand (MaxAvgBw) is greater
   than or equal to the Down-Adjustment-Threshold (percentage or
   absolute value), the LSP bandwidth is adjusted (downsized) to the
   current bandwidth demand (MaxAvgBw).  Some LSPs are less eventful
   while other LSPs may encounter a lot of changes in the traffic
   pattern.  The thresholds and intervals for bandwidth adjustment are
   configured based on the traffic pattern of the LSP.

   In order to avoid frequent re-signaling, an operator may set a longer
   adjustment-interval value (Up and/or Down).  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.  An operator
   needs to configure appropriate values for the Overflow-Threshold
   and/or Underflow-Threshold parameters and they do not have default
   values defined in this document.

   All thresholds in this document could be represented in both absolute
   value and percentage, and could be used together.  This is provided
   to accommodate the cases where the LSP bandwidth reservation may
   become very large or very small over time.  For example, an operator
   may use the percentage threshold to handle small to large bandwidth
   values and absolute values to handle very large bandwidth values.
   The auto-bandwidth adjustment is made when either one of the two
   thresholds, the absolute or percentage, is crossed.

   When using the (adjustment/overflow/underflow) percentage thresholds,
   if the LSP bandwidth changes rapidly at very low values, it may
   trigger frequent auto-bandwidth adjustments due to the crossing of
   the percentage thresholds.  This can lead to unnecessary re-signaling
   of the LSPs in the network.  This is suppressed by setting the
   minimum-threshold parameters along with the percentage thresholds.
   The auto-bandwidth adjustment is only made if the LSP bandwidth
   crosses both the percentage threshold and the minimum-threshold
   parameters.



Dhody, et al.          Expires November 22, 2018                [Page 9]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


4.3.  Scaling Considerations

   It should be noted that any bandwidth change requires re-signaling of
   an LSP in a make-before-break fashion, which can further trigger
   preemption of lower priority LSPs in the network.  When deployed
   under scale, this can lead to a signaling churn in the network.  The
   Auto-bandwidth application algorithm is thus advised to take this
   into consideration before adjusting the LSP bandwidth.  Operators are
   advised to set the values of various auto-bandwidth adjustment
   parameters appropriate for the deployed LSP scale.

   If a PCE gets overwhelmed, it can notify the PCC to temporarily
   suspend the reporting of the new LSP bandwidth to be adjusted (see
   Section 5.7 of this document).  Similarly, if a PCC gets overwhelmed
   due to signaling churn, it can notify the PCE to temporarily suspend
   new LSP setup requests.


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 feature.  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 feature is
   supported as described in this document.

   o  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.

   o  The PCEP speaker that does not recognize the extensions defined in
      this document sends the PCErr message with error-type 2
      (capability not supported) as per Section 6.9 in [RFC5440].

   o  If the PCEP speaker that supports the extensions defined in this
      document but did not advertise this capability, then upon receipt
      of AUTO-BANDWIDTH-ATTRIBUTES TLV in the LSPA object, it SHOULD
      generate a PCErr with error-type 19 (Invalid Operation), error-
      value TBD4 (Auto-Bandwidth capability was not advertised) and
      ignore the AUTO-BANDWIDTH-ATTRIBUTES TLV.

5.1.1.  AUTO-BANDWIDTH-CAPABILITY TLV

   The AUTO-BANDWIDTH-CAPABILITY TLV is an optional TLV for use in the



Dhody, et al.          Expires November 22, 2018               [Page 10]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   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=TBD2       |            Length=4           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Flags                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    AUTO-BANDWIDTH-CAPABILITY TLV format

   The Type of the TLV is (TBD2) and it has a fixed Length of 4 octets.

   The value comprises a single field - Flags (32 bits).  No flags are
   defined for this TLV in this document.

   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-ATTRIBUTES TLV

   The AUTO-BANDWIDTH-ATTRIBUTES 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 [RFC8281], this TLV is included in the LSPA
   Object with the PCInitiate message.  For the PCC-Initiated delegated
   LSPs, this TLV is carried in the PCRpt message in LSPA Object.  This
   TLV is also carried in the LSPA object with the PCUpd message to
   direct the PCC (LSP head-end) to make updates to auto-bandwidth
   attributes such as Adjustment-Interval.

   The TLV is encoded in all PCEP messages for the LSP while the auto-
   bandwidth adjustment feature is enabled, the absence of the TLV
   indicates the PCEP speaker wish to disable the feature.

   The format of the AUTO-BANDWIDTH-ATTRIBUTES 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



Dhody, et al.          Expires November 22, 2018               [Page 11]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


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

                    AUTO-BANDWIDTH-ATTRIBUTES TLV format

   Type: TBD1

   Length: The Length field defines the length of the value portion
           in octets as per [RFC5440].

   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   Down-Adjustment-Interval sub-TLV
    4   4   Adjustment-Threshold sub-TLV
    5   8   Adjustment-Threshold-Percentage sub-TLV
    6   4   Down-Adjustment-Threshold sub-TLV
    7   8   Down-Adjustment-Threshold-Percentage sub-TLV
    8   4   Minimum-Bandwidth sub-TLV
    9   4   Maximum-Bandwidth sub-TLV
   10   8   Overflow-Threshold sub-TLV
   11   8   Overflow-Threshold-Percentage sub-TLV
   12   8   Underflow-Threshold sub-TLV
   13   8   Underflow-Threshold-Percentage sub-TLV

   Future specification can define additional sub-TLVs.

   The sub-TLVs are encoded to inform the PCEP peer the various sampling
   and adjustment parameters.  If sub-TLVs are not present, the default
   values as specified in this document are used or otherwise based on
   the local policy are assumed.

   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 following sub-sections describe the sub-TLVs which are currently



Dhody, et al.          Expires November 22, 2018               [Page 12]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   defined to be carried within the AUTO-BANDWIDTH-ATTRIBUTES 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.

    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

   The Type is 1, Length is 4 octets, and the value comprises of -

   o  Sample-Interval: The 4-octet time interval for bandwidth sample
      collection.  The valid range is from 1 to 604800, in seconds.  The
      default value is 300 seconds.  The sample-interval parameter MUST
      NOT be greater than the (down) adjustment-interval.

5.2.2.  Adjustment Intervals

   The sub-TLVs in this section are encoded to inform the PCEP peer the
   adjustment interval parameters.  An implementation MAY require to set
   different adjustment interval values for when the bandwidth usage
   trend is moving upwards or downwards.  The Adjustment-Interval sub-
   TLV specifies the time interval for both upward and downward trend.
   If the operator would like to use a different adjustment interval
   during the downward trend, the Down-Adjustment-Interval sub-TLV is
   included.

5.2.2.1.  Adjustment-Interval sub-TLV

   The Adjustment-Interval sub-TLV specifies a time interval in seconds
   at which bandwidth adjustment should be made when MaxAvgBw is greater
   than or less than the current bandwidth reservation of the LSP.

    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            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Adjustment-Interval                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



Dhody, et al.          Expires November 22, 2018               [Page 13]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


                    Adjustment-Interval sub-TLV format

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

   o  Adjustment-Interval: The 4-octet time interval for bandwidth
      adjustments.  The valid range is from 1 to 604800, in seconds.
      The default value is 86400 seconds.  The adjustment-interval
      parameter MUST NOT be less than the sample-interval.

5.2.2.2.  Down-Adjustment-Interval sub-TLV

   The Down-Adjustment-Interval sub-TLV specifies a time interval in
   seconds at which bandwidth adjustment should be made when MaxAvgBw is
   less than the current bandwidth reservation of the LSP.  This
   parameter overwrites the Adjustment-Interval for the downward trend.

    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            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Down-Adjustment-Interval                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Down-Adjustment-Interval sub-TLV format

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

   o  Down-Adjustment-Interval: The 4-octet time interval for downward
      bandwidth adjustments.  The valid range is from 1 to 604800, in
      seconds.  The default value equals the adjustment-interval.  The
      down-adjustment-interval parameter MUST NOT be less than the
      sample-interval.

5.2.3.  Adjustment Thresholds

   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.  The Adjustment-Threshold sub-TLV specifies the
   threshold for both upward and downward trend.  If the operator would
   like to use a different adjustment threshold during the downward
   trend, the Down-Adjustment-Threshold sub-TLV is included.  Similarly,
   the Adjustment-Threshold-Percentage sub-TLV specifies the threshold
   percentage for both upward and downward trend.  If the operator would
   like to use a different adjustment threshold percentage during the
   downward trend, the Down-Adjustment-Threshold-Percentage sub-TLV is



Dhody, et al.          Expires November 22, 2018               [Page 14]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   included.

5.2.3.1.  Adjustment-Threshold sub-TLV

   The Adjustment-Threshold sub-TLV is used to decide when the LSP
   bandwidth should be adjusted when MaxAvgBw is greater than or less
   than the current bandwidth reservation.

    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=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Adjustment-Threshold                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Adjustment-Threshold sub-TLV format

   The Type is 4, Length is 4 octets, 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.  The default
      adjustment-threshold value is not set.  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 less than or equal to the
   threshold value, the LSP bandwidth is adjusted to the current
   bandwidth demand (MaxAvgBw).

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 when MaxAvgBw is greater than or
   less than the current bandwidth reservation.

    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=8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Reserved                       |  Percentage |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Minimum-Threshold                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

             Adjustment-Threshold-Percentage sub-TLV format



Dhody, et al.          Expires November 22, 2018               [Page 15]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   The Type is 5, Length is 8 octets, 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 (7 bits), encoded in
      percentage (an integer from 1 to 100).  The value 0 is considered
      to be invalid.  The default value is 5 percent.

   o  Minimum-Threshold: The absolute Minimum-Threshold bandwidth value,
      encoded in IEEE floating point format (see [IEEE.754.1985]),
      expressed in bytes per second.  The increase or decrease of the
      LSP bandwidth should be at least or above the minimum-threshold
      before the bandwidth adjustment is made.  The default value is 0.

   If the percentage difference between the current MaxAvgBw and the
   current bandwidth reservation is greater than or less than or equal
   to the threshold percentage, the LSP bandwidth is adjusted to the
   current bandwidth demand (MaxAvgBw) (as long as the difference in the
   bandwidth is at least or above the Minimum-Threshold).

5.2.3.3.  Down-Adjustment-Threshold sub-TLV

   The Down-Adjustment-Threshold sub-TLV is used to decide when the LSP
   bandwidth should be adjusted when MaxAvgBw is lesser than the current
   bandwidth reservation.  This parameter overwrites the Adjustment-
   Threshold for the downward trend.

    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            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Down-Adjustment-Threshold                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Down-Adjustment-Threshold sub-TLV format

   The Type is 6, Length is 4 octets, and the value comprises of -

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

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



Dhody, et al.          Expires November 22, 2018               [Page 16]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   LSP bandwidth is adjusted to the current bandwidth demand (MaxAvgBw).

5.2.3.4.  Down-Adjustment-Threshold-Percentage sub-TLV

   The Down-Adjustment-Threshold-Percentage sub-TLV is used to decide
   when the LSP bandwidth should be adjusted when MaxAvgBw is lesser
   than the current bandwidth reservation.  This parameter overwrites
   the Adjustment-Threshold-Percentage for the downward trend.

    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                       |  Percentage |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Minimum-Threshold                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Down-Adjustment-Threshold-Percentage sub-TLV format

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

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

   o  Percentage: The Down-Adjustment-Threshold value (7 bits), encoded
      in percentage (an integer from 1 to 100).  The value 0 is
      considered to be invalid.  The default value equals the
      adjustment-threshold-percentage.

   o  Minimum-Threshold: The absolute Minimum-Threshold bandwidth value,
      encoded in IEEE floating point format (see [IEEE.754.1985]),
      expressed in bytes per second.  The decrease of the LSP bandwidth
      should be at least or above the minimum-threshold before the
      bandwidth adjustment is made.  The default value equals the
      minimum-threshold for the adjustment-threshold-percentage.

   If the percentage difference between the current bandwidth
   reservation and the current MaxAvgBw is greater than or equal to the
   threshold percentage, the LSP bandwidth is adjusted to the current
   bandwidth demand (MaxAvgBw) (as long as the difference in the
   bandwidth is at least or above the Minimum-Threshold).

5.2.4.  Minimum and Maximum Bandwidth Values

5.2.4.1.  Minimum-Bandwidth sub-TLV




Dhody, et al.          Expires November 22, 2018               [Page 17]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   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.

    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            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Minimum-Bandwidth                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Minimum-Bandwidth sub-TLV format

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

   o  Minimum-Bandwidth: The 4-octet bandwidth value encoded in IEEE
      floating point format (see [IEEE.754.1985]), expressed in bytes
      per second.  The default minimum-bandwidth value is set to 0.
      Refer to Section 3.1.2 of [RFC3471] for a table of commonly used
      values.

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.

    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=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Maximum-Bandwidth                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Maximum-Bandwidth sub-TLV format

   The Type is 9, Length is 4 octets, and the value comprises of -

   o  Maximum-Bandwidth: The 4-octet bandwidth value encoded in IEEE
      floating point format (see [IEEE.754.1985]), expressed in bytes
      per second.  The default maximum-bandwidth value is not set.
      Refer to Section 3.1.2 of [RFC3471] for a table of commonly used
      values.

5.2.5.  Overflow and Underflow Conditions




Dhody, et al.          Expires November 22, 2018               [Page 18]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   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 an absolute value and/or a percentage for the
   threshold, in which case the bandwidth is immediately adjusted when
   either of the threshold conditions is met consecutively for the given
   count (as long as the difference in the bandwidth is at least or
   above the Minimum-Threshold).  By default, the threshold values for
   overflow and underflow conditions are not set.

5.2.5.1.  Overflow-Threshold sub-TLV

   The Overflow-Threshold sub-TLV is used to decide if the LSP 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=8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Reserved                      |  Count  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Overflow-Threshold                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Overflow-Threshold sub-TLV format

   The Type is 10, Length is 8 octets, 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 (5 bits), 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 (up) 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



Dhody, et al.          Expires November 22, 2018               [Page 19]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   LSP 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=11             |           Length=8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Percentage |             Reserved                  |  Count  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Minimum-Threshold                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Overflow-Threshold-Percentage sub-TLV format

   The Type is 11, Length is 8 octets, and the value comprises of -

   o  Percentage: The Overflow-Threshold value (7 bits), encoded in
      percentage (an integer from 1 to 100).  The value 0 is considered
      to be invalid.  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 (5 bits), 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 (up) adjustment-interval.

   o  Minimum-Threshold: The absolute Minimum-Threshold bandwidth value,
      encoded in IEEE floating point format (see [IEEE.754.1985]),
      expressed in bytes per second.  The increase of the LSP bandwidth
      should be at least or above the minimum-threshold before the
      bandwidth adjustment is made.

5.2.5.3.  Underflow-Threshold sub-TLV

   The Underflow-Threshold sub-TLV is used to decide if the LSP
   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=12             |           Length=8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Reserved                       |  Count  |



Dhody, et al.          Expires November 22, 2018               [Page 20]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Underflow-Threshold                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Underflow-Threshold sub-TLV format

   The Type is 12, Length is 8 octets, 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 (5 bits), 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 down-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
   LSP 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=13             |           Length=8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Percentage |             Reserved                  |  Count  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Minimum-Threshold                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Underflow-Threshold-Percentage sub-TLV format

   The Type is 13, Length is 8 octets, and the value comprises of -

   o  Percentage: The Underflow-Threshold value (7 bits), encoded in
      percentage (an integer from 1 to 100).  The value 0 is considered
      to be invalid.  If the percentage decrease of the current MaxAvgBw
      from the current bandwidth reservation is greater than or equal to



Dhody, et al.          Expires November 22, 2018               [Page 21]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


      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 (5 bits), 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 down-adjustment-interval.

   o  Minimum-Threshold: The absolute Minimum-Threshold bandwidth value,
      encoded in IEEE floating point format (see [IEEE.754.1985]),
      expressed in bytes per second.  The decrease of the LSP bandwidth
      should be at least or above the minimum-threshold before the
      bandwidth adjustment is made.

5.3.  BANDWIDTH Object

   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.

   The PCC reports the calculated bandwidth to be adjusted (MaxAvgBw) to
   the Stateful PCE using the existing 'Requested Bandwidth' with
   BANDWIDTH Object-Type as 1.  The reporting of the 're-optimization
   bandwidth' with BANDWIDTH Object-Type as 2 is not required as the
   Stateful PCE is aware of the existing LSP bandwidth.

5.4.  The PCInitiate Message

   A PCInitiate message is a PCEP message sent by a PCE to a PCC to
   trigger LSP instantiation or deletion [RFC8281].

   For the PCE-Initiated LSP with Auto-Bandwidth feature enabled, AUTO-
   BANDWIDTH-ATTRIBUTES TLV MUST be included in the LSPA object with the
   PCInitiate message.

   The definition (RBNF) of the PCInitiate message [RFC8281] is
   unchanged by this document.

5.5.  The PCUpd Message




Dhody, et al.          Expires November 22, 2018               [Page 22]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   A PCUpd message is a PCEP message sent by a PCE to a PCC to update
   the LSP parameters [RFC8231].

   For PCE-Initiated LSPs with Auto-Bandwidth feature enabled, AUTO-
   BANDWIDTH-ATTRIBUTES TLV MUST be included in the LSPA object with the
   PCUpd message.  The PCE can send this TLV to direct the PCC to change
   the auto-bandwidth parameters.

   The definition (RBNF) of the PCUpd message [RFC8231] is unchanged by
   this document.

5.6.  The PCRpt Message

   The PCRpt message [RFC8231] is a PCEP message sent by a PCC to a PCE
   to report the status of one or more LSPs.

   For PCE-Initiated LSPs [RFC8281], the PCC creates the LSP using the
   attributes communicated by the PCE, and using the local values for
   the unspecified parameters.  After the successful instantiation of
   the LSP, PCC automatically delegates the LSP to the PCE and generates
   a PCRpt message to provide the status report for the LSP.

   For both PCE-Initiated and PCC-Initiated LSPs, when the LSP is
   delegated to a PCE for the very first time as well as after the
   successful delegation, the BANDWIDTH object of type 1 is used to
   specify the requested bandwidth in the PCRpt message.

   For all LSPs with Auto-Bandwidth feature enabled, AUTO-BANDWIDTH-
   ATTRIBUTES TLV MUST be included in the LSPA object of the PCRpt
   message.

   The definition (RBNF) of the PCRpt message [RFC8231] is unchanged by
   this document.

5.7.  The PCNtf Message

   As per [RFC5440], the PCEP Notification message (PCNtf) can be sent
   by a PCEP speaker to notify its peer of a specific event.

   A PCEP speaker (PCE or PCC) SHOULD notify its PCEP peer (PCC or PCE)
   when it is in overwhelmed state due to the auto-bandwidth feature.
   Upon receipt of such notification, the peer SHOULD NOT send any PCEP
   messages related to auto-bandwidth adjustment.  If a PCEP message
   related to auto-bandwidth is received during in overwhelmed state, it
   MUST be silently ignored.

   o  When a PCEP speaker is overwhelmed, it SHOULD notify its peer by
      sending a PCNtf message with Notification Type = TBD3 (Auto-



Dhody, et al.          Expires November 22, 2018               [Page 23]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


      bandwidth Overwhelm State) and Notification Value = 1 (Entering
      auto-bandwidth overwhelm state).  Optionally, OVERLOADED-DURATION
      TLV [RFC5440] MAY be included that specifies the time period
      during which no further PCEP messages related to auto-bandwidth
      adjustment should be sent.

   o  When the PCEP speaker is no longer in the overwhelm state and is
      available to process the auto-bandwidth adjustments, it SHOULD
      notify its peer by sending a PCNtf message with Notification Type
      = TBD3 (Auto-bandwidth Overwhelm State) and Notification Value = 2
      (Clearing auto-bandwidth overwhelm state).

   When Auto-Bandwidth feature is deployed, a PCE can send this
   notification to PCC when a PCC is reporting frequent auto-bandwidth
   adjustments.  If a PCC is overwhelmed with re-signaling, it can also
   notify the PCE to not adjust the LSP bandwidth while in overwhelm
   state.


6.  Security Considerations

   This document defines AUTO-BANDWIDTH-CAPABILITY TLV and
   AUTO-BANDWIDTH-ATTRIBUTES TLV which do not add any new security
   concerns beyond those discussed in [RFC5440] and [RFC8231] in itself.
    Some deployments may find the auto-bandwidth information as extra
   sensitive as it could be used to influence LSP path computation and
   LSP setup with adverse effect.  Additionally, snooping of PCEP
   messages with such data or using PCEP messages for network
   reconnaissance, may give an attacker sensitive information about the
   operations of the network.  Thus, such deployment should employ
   suitable PCEP security mechanisms like TCP Authentication Option
   (TCP-AO) [RFC5925] or [RFC8253].


7.  Manageability Considerations

7.1.  Control of Function and Policy

   The Auto-Bandwidth feature SHOULD be controlled per LSP (at PCC
   (head-end of the LSP) or PCE) and the values for auto-bandwidth
   parameters e.g. sample-interval, adjustment-interval (up/down),
   minimum-bandwidth, maximum-bandwidth, adjustment-threshold (up/down)
   SHOULD be configurable by an operator.

7.2.  Information and Data Models

   A Management Information Base (MIB) module for modeling PCEP is
   described in [RFC7420].  However, one may prefer the mechanism for



Dhody, et al.          Expires November 22, 2018               [Page 24]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   configuration using YANG data model [I-D.ietf-pce-pcep-yang].  These
   SHOULD be enhanced to provide controls and indicators for support of
   auto-bandwidth feature.  Support for various configuration knobs as
   well as counters of messages sent/received containing the TLVs
   defined in this document SHOULD be added.

7.3.  Liveness Detection and Monitoring

   The 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

   The 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

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

7.6.  Impact On Network Operations

   In order to avoid any unacceptable impact on network operations, an
   implementation SHOULD allow a limit to be placed on the number of
   LSPs that can be enabled with auto-bandwidth feature.  An
   implementation MAY allow a limit to be placed on the rate of auto-
   bandwidth related messages sent by a PCEP speaker and received by a
   peer.  An implementation MAY also allow sending a notification when a
   PCEP speaker is overwhelmed or the rate of messages reach a
   threshold.


















Dhody, et al.          Expires November 22, 2018               [Page 25]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


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 the "PCEP TLV Type Indicators"
   sub-registry of the PCEP Numbers registry, as follows:

   Value   Name                                      Reference
   -----------------------------------------------------------------
   TBD2    AUTO-BANDWIDTH-CAPABILITY                 [This document]
   TBD1    AUTO-BANDWIDTH-ATTRIBUTES                 [This document]

8.2.  AUTO-BANDWIDTH-CAPABILITY TLV Flag Field

   IANA is requested to create a sub-registry to manage the Flag field
   of the AUTO-BANDWIDTH-CAPABILITY TLV.

   New bit numbers are to be assigned by Standards Action [RFC8126].
   Each bit should be tracked with the following qualities:

      o  Bit number (counting from bit 0 as the most significant bit)

      o  Capability description

      o  Defining RFC

   There is no bit defined for the AUTO-BANDWIDTH-CAPABILITY TLV Object
   flag field in this document.

8.3.  AUTO-BANDWIDTH-ATTRIBUTES Sub-TLV

   This document specifies the AUTO-BANDWIDTH-ATTRIBUTES Sub-TLVs.  IANA
   is requested to create an "AUTO-BANDWIDTH-ATTRIBUTES Sub-TLV Types"
   sub-registry in the "PCEP TLV Type Indicators" for the sub-TLVs
   carried in the AUTO-BANDWIDTH-ATTRIBUTES TLV.  New sub-TLV are
   assigned by Standards Action [RFC8126].

   This document defines the following types:

   Type Name                                         Reference
   -----------------------------------------------------------------
    0   Reserved                                     [This document]
    1   Sample-Interval sub-TLV                      [This document]
    2   Adjustment-Interval sub-TLV                  [This document]
    3   Down-Adjustment-Interval sub-TLV             [This document]
    4   Adjustment-Threshold sub-TLV                 [This document]
    5   Adjustment-Threshold-Percentage sub-TLV      [This document]



Dhody, et al.          Expires November 22, 2018               [Page 26]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


    6   Down-Adjustment-Threshold sub-TLV            [This document]
    7   Down-Adjustment-Threshold-Percentage sub-TLV [This document]
    8   Minimum-Bandwidth sub-TLV                    [This document]
    9   Maximum-Bandwidth sub-TLV                    [This document]
   10   Overflow-Threshold sub-TLV                   [This document]
   11   Overflow-Threshold-Percentage sub-TLV        [This document]
   12   Underflow-Threshold sub-TLV                  [This document]
   13   Underflow-Threshold-Percentage sub-TLV       [This document]
   14-  Unassigned                                   [This document]
   65535

8.4.  Error Object

   This document defines a new Error-Value for PCErr message of Error-
   Type 19 (Invalid Operation) [RFC8231].  IANA is requested to allocate
   new error-value within the "PCEP-ERROR Object Error Types and Values"
   subregistry of the PCEP Numbers registry, as follows:

   Error-Type Meaning & error values                 Reference
   -----------------------------------------------------------------
   19         Invalid Operations

              Error-Value = TBD4:                    [This document]
              Auto-Bandwidth Capability
              was not Advertised

8.5.  Notification Object

   IANA is requested to allocate new Notification Types and Notification
   Values within the "Notification Object" sub-registry of the PCEP
   Numbers registry, as follows:

   Type        Meaning                               Reference
   -----------------------------------------------------------------
   TBD3        Auto-Bandwidth Overwhelm State        [This document]

               Notification-value=1:    Entering Auto-Bandwidth
                                        overwhelm state
               Notification-value=2:    Clearing Auto-Bandwidth
                                        overwhelm state











Dhody, et al.          Expires November 22, 2018               [Page 27]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


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.

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

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8231]  Crabbe, E., Minei, I., Medved, J., and R. Varga, "Pah
              Computation Element Communication Protocol (PCEP)
              Extensions for Stateful PCE", RFC 8231, DOI
              10.17487/RFC8231, September 2017,  <https://www.rfc-
              editor.org/infor/rfc8231>.

   [RFC8281]  Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
              Computation Element Communication Protocol (PCEP)
              Extensions for PCE-Initiated LSP Setup in a Stateful PCE
              Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
              <https://www.rfc-editor.org/info/rfc8281>.

9.2.  Informative References

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

   [RFC5925]  Touch, J., Mankin, A., and R. Bonica, "The TCP
              Authentication Option", RFC 5925, June 2010.

   [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.

   [RFC8051]  Zhang, X. and I. Minei, "Applicability of a Stateful Path
              Computation Element (PCE)", RFC 8051, January 2017.



Dhody, et al.          Expires November 22, 2018               [Page 28]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


   [RFC8253]  Lopez, D., Dios, O., Wu, W., and D. Dhody, "PCEPS: Usage
              of TLS to Provide a Secure Transport for the Path
              Computation Element Communication Protocol (PCEP)", RFC
              8253, October 2017, <https://www.rfc-
              editor.org/info/rfc8253>.

   [I-D.ietf-pce-pcep-yang]  Dhody, D., Hardwick, J., Beeram, V., and J.
              Tantsura, "A YANG Data Model for Path Computation Element
              Communications Protocol (PCEP)", draft-ietf-pce-pcep-yang
              (work in progress).

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





































Dhody, et al.          Expires November 22, 2018               [Page 29]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


Acknowledgments

   Authors would like to thank Robert Varga, Venugopal Reddy, Reeja
   Paul, Sandeep Boina, Avantika, JP Vasseur, Himanshu Shah and Adrian
   Farrel 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















Dhody, et al.          Expires November 22, 2018               [Page 30]


Internet-Draft      Auto-Bandwidth with Stateful PCE        May 21, 2018


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: udayasreereddy@gmail.com


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

   Email: ravis@juniper.net


   Rakesh Gandhi
   Cisco Systems, Inc.

   Email: rgandhi@cisco.com


   Luyuan Fang
   Expedia, Inc.
   USA

   Email: luyuanf@gmail.com











Dhody, et al.          Expires November 22, 2018               [Page 31]


Html markup produced by rfcmarkup 1.127, available from https://tools.ietf.org/tools/rfcmarkup/