[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 08 09 10 11 12

PCE Working Group                                          D. Dhody, Ed.
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                          R. Gandhi, Ed.
Expires: March 29, 2020                              Cisco Systems, Inc.
                                                                U. Palle
                                                                R. Singh
                                                  Individual Contributor
                                                                 L. Fang
                                                           Expedia, Inc.
                                                      September 26, 2019


  PCEP Extensions for MPLS-TE LSP Automatic Bandwidth Adjustment with
                              Stateful PCE
              draft-ietf-pce-stateful-pce-auto-bandwidth-12

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.

   The automatic bandwidth feature 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 https://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 March 29, 2020                 [Page 1]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


Copyright Notice

   Copyright (c) 2019 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
   (https://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 . . . . . . . . . . . .  9
     4.3.  Scaling Considerations . . . . . . . . . . . . . . . . . . 10
   5.  PCEP Extensions  . . . . . . . . . . . . . . . . . . . . . . . 10
     5.1.  Capability Advertisement . . . . . . . . . . . . . . . . . 10
       5.1.1.  AUTO-BANDWIDTH-CAPABILITY TLV  . . . . . . . . . . . . 11
     5.2.  AUTO-BANDWIDTH-ATTRIBUTES TLV  . . . . . . . . . . . . . . 12
       5.2.1.  Sample-Interval sub-TLV  . . . . . . . . . . . . . . . 13
       5.2.2.  Adjustment Intervals . . . . . . . . . . . . . . . . . 14
         5.2.2.1.  Adjustment-Interval sub-TLV  . . . . . . . . . . . 14
         5.2.2.2.  Down-Adjustment-Interval sub-TLV . . . . . . . . . 14
       5.2.3.  Adjustment Thresholds  . . . . . . . . . . . . . . . . 15
         5.2.3.1.  Adjustment-Threshold sub-TLV . . . . . . . . . . . 15
         5.2.3.2.  Adjustment-Threshold-Percentage sub-TLV  . . . . . 16
         5.2.3.3.  Down-Adjustment-Threshold sub-TLV  . . . . . . . . 17
         5.2.3.4.  Down-Adjustment-Threshold-Percentage sub-TLV . . . 18
       5.2.4.  Minimum and Maximum Bandwidth Values . . . . . . . . . 19
         5.2.4.1.  Minimum-Bandwidth sub-TLV  . . . . . . . . . . . . 19
         5.2.4.2.  Maximum-Bandwidth sub-TLV  . . . . . . . . . . . . 19
       5.2.5.  Overflow and Underflow Conditions  . . . . . . . . . . 20
         5.2.5.1.  Overflow-Threshold sub-TLV . . . . . . . . . . . . 20



Dhody, et al.            Expires March 29, 2020                 [Page 2]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


         5.2.5.2.  Overflow-Threshold-Percentage sub-TLV  . . . . . . 21
         5.2.5.3.  Underflow-Threshold sub-TLV  . . . . . . . . . . . 22
         5.2.5.4.  Underflow-Threshold-Percentage sub-TLV . . . . . . 23
     5.3.  BANDWIDTH Object . . . . . . . . . . . . . . . . . . . . . 24
     5.4.  The PCInitiate Message . . . . . . . . . . . . . . . . . . 24
     5.5.  The PCUpd Message  . . . . . . . . . . . . . . . . . . . . 24
     5.6.  The PCRpt Message  . . . . . . . . . . . . . . . . . . . . 24
     5.7.  The PCNtf Message  . . . . . . . . . . . . . . . . . . . . 25
   6.  Manageability Considerations . . . . . . . . . . . . . . . . . 26
     6.1.  Control of Function and Policy . . . . . . . . . . . . . . 26
     6.2.  Information and Data Models  . . . . . . . . . . . . . . . 26
     6.3.  Liveness Detection and Monitoring  . . . . . . . . . . . . 27
     6.4.  Verify Correct Operations  . . . . . . . . . . . . . . . . 27
     6.5.  Requirements On Other Protocols  . . . . . . . . . . . . . 27
     6.6.  Impact On Network Operations . . . . . . . . . . . . . . . 27
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 28
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 28
     8.1.  PCEP TLV Type Indicators . . . . . . . . . . . . . . . . . 28
     8.2.  AUTO-BANDWIDTH-CAPABILITY TLV Flag Field . . . . . . . . . 28
     8.3.  AUTO-BANDWIDTH-ATTRIBUTES Sub-TLV  . . . . . . . . . . . . 29
     8.4.  Error Object . . . . . . . . . . . . . . . . . . . . . . . 29
     8.5.  Notification Object  . . . . . . . . . . . . . . . . . . . 30
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 31
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 31
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 31
   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . . . 33
   Contributors' Addresses  . . . . . . . . . . . . . . . . . . . . . 33
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 34






1.  Introduction

   [RFC5440] describes the Path Computation Element Protocol (PCEP) as a
   communication mechanism between a Path Computation Client (PCC) and a
   Path Computation 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 March 29, 2020                 [Page 3]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   Over time, based on the varying traffic pattern, an LSP established
   with a certain bandwidth may require adjustment of 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, when available in the head-
   end Label Switching Router (LSR) implementation, is common 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 a
   path request/reply mechanism, the Active stateful PCE uses a
   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.

   Another approach would be to send the measured values itself to the
   PCE, which is considered out of scope for this document.

   This document defines the PCEP extensions needed to support an Auto-
   Bandwidth feature in an 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.




Dhody, et al.            Expires March 29, 2020                 [Page 4]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   PCEP:  Path Computation Element Communication Protocol.

   TE LSP:  Traffic Engineering Label Switched Path.


2.3.  Terminology

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

   In this document, the PCC is considered to be the head end LSR of the
   LSP. Other types of PCC are not in scope.

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

   Maximum Average Bandwidth (MaxAvgBw):  The maximum average bandwidth
      represents the current 'measured' 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 time
      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 less 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



Dhody, et al.            Expires March 29, 2020                 [Page 5]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


      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
      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
      needs to be greater than or equal to the Overflow-Threshold value
      in order to meet the overflow condition.

   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 said 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. The Overflow-Threshold needs to be greater than or equal to
      the Up-Adjustment-Threshold.

   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
      needs to be greater than or equal to the Underflow-Threshold value
      in order to meet the underflow condition.

   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 said 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-



Dhody, et al.            Expires March 29, 2020                 [Page 6]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


      Count. The Underflow-Threshold needs to be greater than or equal
      to the Down-Adjustment-Threshold.

   Minimum-Threshold: When percentage-based thresholds are in use, they
      are accompanied by this minimum threshold, which is used to
      enforce that the magnitude of deviation of calculated LSP
      bandwidth to be adjusted from the current bandwidth reservations
      exceeds a specific non-percentage-based criterion (represented as
      an absolute bandwidth value) before any adjustments are made. This
      serves to suppress unnecessary auto-bandwidth adjustments and re-
      signaling of the LSP at low bandwidth values.


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)
                               |    |



Dhody, et al.            Expires March 29, 2020                 [Page 7]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


                               |    |  REQUESTED BANDWIDTH
                               v    |
                             ----------
                            |          |
                            |   PCC    |
                            |          |
                             ----------

        Figure 1: Overview of Auto-Bandwidth PCEP extensions


   A PCEP speaker supporting this document must have a mechanism to
   advertise the automatic bandwidth adjustment capability for both PCC-
   Initiated and PCE-Initiated LSPs.

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

   o  It is necessary to identify and inform the PCC which LSPs have
      enabled the Auto-Bandwidth feature.  Not all LSPs in some
      deployments would like their bandwidth to be dependent on the
      real-time bandwidth usage; for some LSPs leaving the bandwidth
      constant as set by the operator is preferred.

   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

   The 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 set to an 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.



Dhody, et al.            Expires March 29, 2020                 [Page 8]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   Bandwidth adjustment must not cause disruption to the traffic flow
   carried by the LSP.  One way to achieve this is to use the
   make-before-break signaling method [RFC3209].


4.2.  Auto-bandwidth Theory of Operation

   This section describes the Auto-Bandwidth feature in a general way.
   When the Auto-Bandwidth feature is enabled, the measured traffic rate
   is periodically sampled at each Sample-Interval by the PCC, when the
   PCC is the head-end node of the LSP.  The sample interval can be
   configured by an operator, with a default value of 5 minutes. A very
   low Sample-Interval could have some undesirable interactions with
   transport protocols (see Section 6.6).

   The traffic rate samples are accumulated over the Adjustment-Interval
   period (in the Up or Down direction).  The period can be configured
   by an operator, with a default value of 24 hours. The PCC in-charge
   of calculating the bandwidth to be adjusted can decide to adjust the
   bandwidth of the LSP to the highest traffic rate sample (MaxAvgBw)
   amongst the set of bandwidth samples collected over the
   Adjustment-Interval period (in the Up or Down direction) depending on
   the operator policy.

   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 the
   LSP bandwidth is adjusted (upsized) to the current bandwidth demand
   (MaxAvgBw). The Adjustment-Threshold could be an absolute value or a
   percentage. The threshold can be configured by an operator, with a
   default value of 5 percentage. 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, a 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 prematurely 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



Dhody, et al.            Expires March 29, 2020                 [Page 9]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   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.


4.3.  Scaling Considerations

   It should be noted that any bandwidth change requires re-signaling of
   an LSP, 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 (see Section 5.7 of this document).


5.  PCEP Extensions

5.1.  Capability Advertisement

   During PCEP Initialization Phase, PCEP speakers (PCE or PCC)
   advertise their support of Automatic Bandwidth adjustment feature.  A



Dhody, et al.            Expires March 29, 2020                [Page 10]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   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  A PCEP speaker that does not recognize the extensions defined in
      this document would simply ignore the TLVs as per [RFC5440].

   o  If a 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 LSP Attributes (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
   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.




Dhody, et al.            Expires March 29, 2020                [Page 11]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


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 wishes to disable the feature.  This TLV
   includes multiple AUTO-BANDWIDTH-ATTRIBUTES sub-TLVs.  The
   AUTO-BANDWIDTH-ATTRIBUTES sub-TLVs are included if there is a change
   since the last information sent in the PCEP message.  The default
   values for missing sub-TLVs apply for the first PCEP message for the
   LSP.

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           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
   -------------------------------------------------------------------



Dhody, et al.            Expires March 29, 2020                [Page 12]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


    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 specifications can define additional sub-TLVs.

   The sub-TLVs are encoded to inform the PCEP peer of the various
   sampling and adjustment parameters.  In case of a missing sub-TLV, as
   per the local policy, either the default value (as specified in this
   document) or some other operator configured value is used.

   All sub-TLVs are optional and any unrecognized sub-TLV MUST be
   ignored.  If a sub-TLV of the 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
   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 (7 days), in
      seconds.  The default value is 300 seconds.  Due care needs to be



Dhody, et al.            Expires March 29, 2020                [Page 13]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


      taken in case of a very low Sample-Interval, as it can have some
      undesirable interactions with transport protocols (see Section
      6.6). The sample-interval parameter MUST NOT be greater than the
      (down) adjustment-interval. In case of an invalid value, the Sub-
      TLV MUST be ignored and the previous value is maintained.

5.2.2.  Adjustment Intervals

   The sub-TLVs in this section are encoded to inform the PCEP peer the
   adjustment interval parameters.  The Adjustment-Interval sub-TLV
   specifies the time interval for both upward (Up-Adjustment-Interval)
   and downward (Down-Adjustment-Interval) trends. An implementation MAY
   require to set a different adjustment interval values for when the
   bandwidth usage trend is downwards from when it is moving upwards. In
   that case, the operator could use the Down-Adjustment-Interval sub-
   TLV which overrides the Adjustment-Interval value for Down-
   Adjustment-Interval.

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 in upward or downward
   direction. This sub-TLV specify the value for Up-Adjustment-Interval
   and Down-Adjustment-Interval when they are the same and the Down-
   Adjustment-Interval sub-TLV is not included.

    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                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    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 (7 days), in
      seconds.  The default value is 86400 seconds (1 day).  The
      adjustment-interval parameter MUST NOT be less than the
      sample-interval, otherwise the Sub-TLV MUST be ignored and the
      previous value is maintained.

5.2.2.2.  Down-Adjustment-Interval sub-TLV

   The Down-Adjustment-Interval sub-TLV specifies a time interval in



Dhody, et al.            Expires March 29, 2020                [Page 14]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   seconds at which bandwidth adjustment should be made when MaxAvgBw is
   less than the current bandwidth reservation of the LSP.  This
   parameter overrides the Adjustment-Interval for the downward trend.
   This sub-TLV is used only when there is a need for different
   adjustment intervals in the upward and downward directions.


    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 (7
      days), in seconds.  The default value equals the adjustment-
      interval.  The down-adjustment-interval parameter MUST NOT be less
      than the sample-interval, otherwise the Sub-TLV MUST be ignored
      and the previous value is maintained.

5.2.3.  Adjustment Thresholds

   The sub-TLVs in this section are encoded to inform the PCEP peer of
   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 (Up-Adjustment-Threshold) and
   downward (Down-Adjustment-Threshold) 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
   included.  It is worth noting that regardless of how the threshold
   are set, the adjustment will not be made until at least one sample-
   interval simply because no sample will be made on which to base a
   comparison with a threshold.

5.2.3.1.  Adjustment-Threshold sub-TLV




Dhody, et al.            Expires March 29, 2020                [Page 15]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   The Adjustment-Threshold sub-TLV is used to decide when the LSP
   bandwidth should be adjusted in upward or downward direction. This
   sub-TLV specify the absolute value for Up-Adjustment-Threshold and
   Down-Adjustment-Threshold when they are the same and the Down-
   Adjustment-Threshold sub-TLV is not included.

    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
      difference 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 modulus of 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 (MaxAvgBw).

   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.

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 in upward or downward direction.
   This sub-TLV specify the percentage value for Up-Adjustment-Threshold
   and Down-Adjustment-Threshold when they are the same and the Down-
   Adjustment-Threshold-Percentage sub-TLV is not included.

    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                      |



Dhody, et al.            Expires March 29, 2020                [Page 16]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


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

             Adjustment-Threshold-Percentage sub-TLV format

   The Type is 5, Length is 8 octets, and the value comprises of -

   o  Reserved: MUST 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 MUST be at least or above the minimum-threshold
      before the bandwidth adjustment is made.  The default value is 0.

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

   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.

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 overrides the Adjustment-
   Threshold for the downward trend. This sub-TLV is used only when
   there is a need for different threshold in the upward and downward
   directions.

    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 -



Dhody, et al.            Expires March 29, 2020                [Page 17]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


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

   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.

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 overrides the
   Adjustment-Threshold-Percentage for the downward trend. This sub-TLV
   is used only when there is a need for different threshold percentage
   in the upward and downward directions.

    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: MUST 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
      MUST be at least or above the minimum-threshold before the



Dhody, et al.            Expires March 29, 2020                [Page 18]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


      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, and the difference in the bandwidth is at least
   or above the Minimum-Threshold, the LSP bandwidth is adjusted to the
   current bandwidth demand (MaxAvgBw).

   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.

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.

    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.

   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.

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



Dhody, et al.            Expires March 29, 2020                [Page 19]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


    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.

   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.

5.2.5.  Overflow and Underflow Conditions

   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




Dhody, et al.            Expires March 29, 2020                [Page 20]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   The Type is 10, Length is 8 octets, and the value comprises of -

   o  Reserved: MUST 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
      difference of the current MaxAvgBw from the current bandwidth
      reservation is greater than or equal to the threshold value, the
      overflow condition is met.

   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.

5.2.5.2.  Overflow-Threshold-Percentage sub-TLV

   The Overflow-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=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: MUST be set to zero on transmission and MUST be ignored



Dhody, et al.            Expires March 29, 2020                [Page 21]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


      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
      MUST be at least or above the minimum-threshold before the
      bandwidth adjustment is made.

   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.

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

                    Underflow-Threshold sub-TLV format

   The Type is 12, Length is 8 octets, and the value comprises of -

   o  Reserved: MUST 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



Dhody, et al.            Expires March 29, 2020                [Page 22]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


      3.1.2 of [RFC3471] for a table of commonly used values.  If the
      difference of the current MaxAvgBw from the current bandwidth
      reservation is greater than or equal to the threshold value, the
      underflow condition is met.

   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.


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
      the threshold percentage, the underflow condition is met.

   o  Reserved: MUST 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
      MUST be at least or above the minimum-threshold before the
      bandwidth adjustment is made.



Dhody, et al.            Expires March 29, 2020                [Page 23]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   In case of an invalid value, the Sub-TLV MUST be ignored and the
   previous value is maintained.

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 Routing Backus-Naur Format (RBNF) definition of the PCInitiate
   message [RFC8281] is unchanged by this document.

5.5.  The PCUpd Message

   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 RBNF definition 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



Dhody, et al.            Expires March 29, 2020                [Page 24]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   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.

   The RBNF definition 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.
   An implementation needs to make an attempt to send this notification
   (when overwhelmed by auto-bandwidth adjustments) unless sending this
   notification would only serve to increase the load further. Note that
   when the notification is not received the PCEP speaker would continue
   to request bandwidth adjustments even when they could not be handled
   in a timely fashion.

   Upon receipt of auto-bandwidth overwhelm notification, the peer
   SHOULD NOT send any PCEP messages related to auto-bandwidth
   adjustment.  If a PCEP message related to auto-bandwidth adjustment
   is received during in overwhelmed state, it MUST be ignored.

   o  When a PCEP speaker is overwhelmed, it SHOULD notify its peer by
      sending a PCNtf message with Notification-Type = TBD3 (Auto-
      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 peers by sending a PCNtf message with Notification Type
      = TBD3 (Auto-bandwidth Overwhelm State) and Notification Value = 2
      (Clearing auto-bandwidth overwhelm state). A PCEP speaker SHOULD



Dhody, et al.            Expires March 29, 2020                [Page 25]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


      send such notification to all peers to with a Notification message
      (Notification-Type=TBD3, Notification-Value=1) was sent earlier
      unless an OVERLOADED-DURATION TLV was included and the PCEP
      speakers wishes for the peer to wait for the expiration of that
      period of time before receiving further PCEP messages related to
      auto-bandwidth adjustment.

   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.

   Some dampening notification procedure (as per [RFC5440]) to avoid
   oscillations of the overwhelm state is RECOMMENDED. On receipt of an
   auto-bandwidth overwhelm notification from the PCE, a PCC should
   consider the impact on the entire network. Moving the delegations of
   auto-bandwidth enabled LSP to another PCE could cause further
   overloading.


6.  Manageability Considerations

6.1.  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.

   The Maximum-Bandwidth (and Minimum-Bandwidth) should be set to
   acceptable limit to avoid impact on the rest of the MPLS-TE domain.

   The operator should make sure that the Overflow-Threshold is greater
   than or at least equal to the Up-Adjustment-Threshold. And similarly,
   make sure that the Underflow-Threshold is greater than or at least
   equal to the Down-Adjustment-Threshold.

6.2.  Information and Data Models

   A MIB module for gathering operational information about PCEP is
   defined in [RFC7420].  Additionally, the YANG module defined in
   [I-D.ietf-pce-pcep-yang] provides for both configuration of PCEP as
   well as operational management.  These could 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



Dhody, et al.            Expires March 29, 2020                [Page 26]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   could be added.

6.3.  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].

6.4.  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].

   In case of an invalid value, the Sub-TLV would get ignored and the
   previous value would be maintained. In such case the implementation
   SHOULD log the event.

6.5.  Requirements On Other Protocols

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

6.6.  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.  For each LSP
   enabled with auto-bandwidth feature there is an extra load on PCC, as
   it needs to monitor the traffic and report the calculated bandwidth
   to be adjusted to the PCE. The PCE further re-compute paths based on
   the requested bandwidth and update the path to the PCC, which in
   turns triggers the re-signaling of the path. All these steps adds
   extra load and churn in the network and thus operator needs to take
   due care while enabling this features on a number of LSPs.

   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 SHOULD also allow sending a notification
   when a PCEP speaker is overwhelmed or the rate of messages reach a
   threshold.

   Due care is required by the operator if a Sample-Interval value
   significantly smaller than the default (5 minute) is used, as a small
   Sample-Interval values, e.g., 1 minute or less, could cause
   undesirable interactions with transport protocols. These undesirable
   interactions result from providing insufficient time for transport
   protocol reactions to a prior bandwidth adjustment to settle out



Dhody, et al.            Expires March 29, 2020                [Page 27]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   before bandwidth samples are taken for the next bandwidth adjustment.

7.  Security Considerations

   This document defines AUTO-BANDWIDTH-CAPABILITY TLV and AUTO-
   BANDWIDTH-ATTRIBUTES sub-TLVs which do not add any substantial new
   security concerns beyond those already discussed in [RFC8231] and
   [RFC8281] for stateful PCE operations.  As per [RFC8231], it is
   RECOMMENDED that these PCEP extensions only be activated on
   authenticated and encrypted sessions across PCEs and PCCs belonging
   to the same administrative authority, using Transport Layer Security
   (TLS) [RFC8253], as per the recommendations and best current
   practices in BCP 195 [RFC7525] (unless explicitly set aside in
   [RFC8253]).

   Incorrect auto-bandwidth parameters in the AUTO-BANDWIDTH-ATTRIBUTES
   sub-TLVs could have an adverse effect on the LSP as well as on the
   network.

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 within the "Path Computation
   Element Protocol (PCEP) Numbers" registry.

   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

   The initial contents of the sub-registry are empty, with all bits



Dhody, et al.            Expires March 29, 2020                [Page 28]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   marked unassigned

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 within the "Path Computation Element Protocol (PCEP)
   Numbers" registry to manage the type indicator space for sub-TLVs of
   the AUTO-BANDWIDTH-ATTRIBUTES TLV.  The valid range of values in the
   registry is 0-65535.  IANA is requested to initialize the registry
   with the following values.  All other values in the registry should
   be marked as "Unassigned".

   IANA is requested to set the registration procedure for this registry
   to read as follows:

           0-65503    IETF Review
       65504-65535    Experimental Use

   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]
    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]
   65503

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



Dhody, et al.            Expires March 29, 2020                [Page 29]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   -----------------------------------------------------------------
   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 Type 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 March 29, 2020                [Page 30]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


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.

   [RFC7525]  Sheffer, Y., Holz, R. and P. Saint-Andre, "Recommendations
              for Secure Use of Transport Layer Security (TLS) and
              Datagram Transport Layer Security (DTLS)", BCP 195, RFC
              7525, DOI 10.17487/RFC7525, May 2015.

   [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>.

   [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>.

   [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>.

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

9.2.  Informative References



Dhody, et al.            Expires March 29, 2020                [Page 31]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
              <https://www.rfc-editor.org/info/rfc3209>.

   [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.

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

   [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).






























Dhody, et al.            Expires March 29, 2020                [Page 32]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


Acknowledgments

   Authors would like to thank Robert Varga, Venugopal Reddy, Reeja
   Paul, Sandeep Boina, Avantika, JP Vasseur, Himanshu Shah, Jonathan
   Hardwick and Adrian Farrel for their useful comments and suggestions.

   Thanks to Daniel Franke, Joe Clarke, David Black, and Erik Kline for
   the directorate reviews.

   Thanks to Mirja Kuhlewind, Barry Leiba, Benjamin Kaduk, and Roman
   Danyliw for the IESG review.

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
   SKKU

   Email: younglee.tx@gmail.com















Dhody, et al.            Expires March 29, 2020                [Page 33]


Internet-Draft      Auto-Bandwidth with Stateful PCE  September 26, 2019


Authors' Addresses

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

   Email: dhruv.ietf@gmail.com

   Rakesh Gandhi (editor)
   Cisco Systems, Inc.
   Canada

   Email: rgandhi@cisco.com

   Udayasree Palle
   Individual Contributor

   Email: udayasreereddy@gmail.com

   Ravi Singh
   Individual Contributor

   Email: ravi.singh.ietf@gmail.com

   Luyuan Fang
   Expedia, Inc.
   USA

   Email: luyuanf@gmail.com




















Dhody, et al.            Expires March 29, 2020                [Page 34]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/