PCEP Extensions for MPLS-TE LSP Automatic Bandwidth Adjustment with Stateful PCE
draft-ietf-pce-stateful-pce-auto-bandwidth-04
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Authors | Dhruv Dhody , Udayasree Palle , Ravi Singh , Rakesh Gandhi , Luyuan Fang | ||
| Last updated | 2017-04-17 | ||
| Replaces | draft-dhody-pce-stateful-pce-auto-bandwidth | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-pce-stateful-pce-auto-bandwidth-04
PCE Working Group D. Dhody
Internet-Draft U. Palle
Intended status: Standards Track Huawei Technologies
Expires: October 19, 2017 R. Singh
Juniper Networks
R. Gandhi
Cisco Systems, Inc.
L. Fang
eBay
April 17, 2017
PCEP Extensions for MPLS-TE LSP Automatic Bandwidth Adjustment with
Stateful PCE
draft-ietf-pce-stateful-pce-auto-bandwidth-04
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."
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Copyright Notice
Copyright (c) 2017 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
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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 . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
3. Requirements for PCEP Extensions . . . . . . . . . . . . . . . 7
4. Architectural Overview . . . . . . . . . . . . . . . . . . . . 7
4.1. Auto-Bandwidth Overview . . . . . . . . . . . . . . . . . 7
4.2. Auto-bandwidth Theory of Operation . . . . . . . . . . . . 8
4.3. Scaling Considerations . . . . . . . . . . . . . . . . . . 9
5. Extensions to the PCEP . . . . . . . . . . . . . . . . . . . . 9
5.1. Capability Advertisement . . . . . . . . . . . . . . . . . 9
5.1.1. AUTO-BANDWIDTH-CAPABILITY TLV . . . . . . . . . . . . 10
5.2. AUTO-BANDWIDTH-ATTRIBUTES TLV . . . . . . . . . . . . . . 10
5.2.1. Sample-Interval sub-TLV . . . . . . . . . . . . . . . 12
5.2.2. Adjustment Intervals . . . . . . . . . . . . . . . . . 12
5.2.2.1. Adjustment-Interval sub-TLV . . . . . . . . . . . 12
5.2.2.2. Down-Adjustment-Interval sub-TLV . . . . . . . . . 13
5.2.3. Adjustment Thresholds . . . . . . . . . . . . . . . . 13
5.2.3.1. Adjustment-Threshold sub-TLV . . . . . . . . . . . 14
5.2.3.2. Adjustment-Threshold-Percentage sub-TLV . . . . . 14
5.2.3.3. Down-Adjustment-Threshold sub-TLV . . . . . . . . 15
5.2.3.4. Down-Adjustment-Threshold-Percentage sub-TLV . . . 15
5.2.4. Minimum and Maximum Bandwidth Values . . . . . . . . . 16
5.2.4.1. Minimum-Bandwidth sub-TLV . . . . . . . . . . . . 16
5.2.4.2. Maximum-Bandwidth sub-TLV . . . . . . . . . . . . 17
5.2.5. Overflow and Underflow Conditions . . . . . . . . . . 17
5.2.5.1. Overflow-Threshold sub-TLV . . . . . . . . . . . . 17
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5.2.5.2. Overflow-Threshold-Percentage sub-TLV . . . . . . 18
5.2.5.3. Underflow-Threshold sub-TLV . . . . . . . . . . . 19
5.2.5.4. Underflow-Threshold-Percentage sub-TLV . . . . . . 19
5.3. BANDWIDTH Object . . . . . . . . . . . . . . . . . . . . . 20
5.4. The PCInitiate Message . . . . . . . . . . . . . . . . . . 20
5.5. The PCUpd Message . . . . . . . . . . . . . . . . . . . . 21
5.6. The PCRpt Message . . . . . . . . . . . . . . . . . . . . 21
5.7. The PCNtf Message . . . . . . . . . . . . . . . . . . . . 21
6. Security Considerations . . . . . . . . . . . . . . . . . . . 22
7. Manageability Considerations . . . . . . . . . . . . . . . . . 22
7.1. Control of Function and Policy . . . . . . . . . . . . . . 22
7.2. Information and Data Models . . . . . . . . . . . . . . . 23
7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 23
7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 23
7.5. Requirements On Other Protocols . . . . . . . . . . . . . 23
7.6. Impact On Network Operations . . . . . . . . . . . . . . . 23
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
8.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . . 24
8.2. AUTO-BANDWIDTH-CAPABILITY TLV Flag Field . . . . . . . . . 24
8.3. AUTO-BANDWIDTH-ATTRIBUTES Sub-TLV . . . . . . . . . . . . 24
8.4. Error Object . . . . . . . . . . . . . . . . . . . . . . . 25
8.5. Notification Object . . . . . . . . . . . . . . . . . . . 25
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9.1. Normative References . . . . . . . . . . . . . . . . . . . 26
9.2. Informative References . . . . . . . . . . . . . . . . . . 26
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 28
Contributors' Addresses . . . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29
1. Introduction
[RFC5440] describes the Path Computation Element Protocol (PCEP) as a
communication mechanism between a Path Computation Client (PCC) and a
Path Control Element (PCE), or between PCE and PCE, that enables
computation of Multi-Protocol Label Switching (MPLS) Traffic
Engineering Label Switched Paths (TE LSPs).
[I-D.ietf-pce-stateful-pce] specifies extensions to PCEP to enable
stateful control of MPLS TE LSPs. It describes two mode of
operations - Passive stateful PCE and Active stateful PCE. Further,
[I-D.ietf-pce-pce-initiated-lsp] 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
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controlled by the PCE.
Over time, based on the varying traffic pattern, an LSP established
with certain bandwidth may require to adjust the bandwidth reserved
in the network automatically. The head-end Label Switch Router (LSR)
needs to monitor the actual bandwidth demand of the LSP and adjust
the LSP bandwidth reservation periodically. This feature is commonly
referred to as Auto-Bandwidth. Enabling Auto-Bandwidth feature on an
LSP results in the head-end LSR automatically adjusting the LSP
bandwidth reservation based on the traffic flowing through the LSP.
The initial LSP bandwidth can be set to an arbitrary value (including
zero), in practice, it can be operator expected value based on design
and planning. Once the LSP is set-up, the head-end monitors the
traffic flow on the LSP and adjusts the bandwidth reservation
periodically. The Auto-Bandwidth feature is described in detail in
Section 4 of 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 a passive stateful PCE model, while the passive
stateful PCE uses path request/reply mechanism, the active stateful
PCE uses report/update mechanism to adjust the LSP bandwidth. 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.
The document [I-D.gandhi-pce-pm] describes the PCEP extensions for
reporting the performance measurements to the PCE, and includes the
real-time bandwidth utilization information of a TE LSP. Those
extensions can be used to implement the auto-bandwidth feature on a
stateful PCE, i.e. can be used to calculate the new bandwidth to be
adjusted on the stateful PCE.
This document defines the extensions needed to support Auto-Bandwidth
features on the LSPs in a active stateful PCE model using PCEP where
the bandwidth to be adjusted is calculated on the PCC (head-end of
the LSP).
2. Conventions Used in This Document
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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2.2. Abbreviations
PCC: Path Computation Client.
PCE: Path Computation Element.
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], [I-D.ietf-pce-pce-initiated-lsp], and [I-D.ietf-pce-
stateful-pce].
The following auto-bandwidth terminology is defined in this document.
Maximum Average Bandwidth (MaxAvgBw): The maximum average bandwidth
represents the current traffic bandwidth demand during a time
interval. This is the maximum value of the 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 is collected as a Bandwidth-Sample.
Bandwidth-Sample: The bandwidth sample of the measured traffic rate
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.
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.
Up-Adjustment-Threshold: This parameter is used to decide when the
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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
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 bandwidth
should be adjusted when there is a sudden increase in traffic
demand. This value indicates how many times consecutively, the
percentage or absolute difference between the current MaxAvgBw and
the current bandwidth reservation is greater than or equal to the
Overflow-Threshold value.
Overflow-Threshold: This parameter is used to decide when the
bandwidth should be adjusted when there is a sudden increase in
traffic demand. If the percentage or absolute difference between
the current MaxAvgBw and the current bandwidth reservation is
greater than or equal to the threshold value, the overflow
condition is set to be met. The LSP bandwidth is adjusted to the
current bandwidth demand bypassing the Up-Adjustment-Interval if
the overflow condition is met consecutively for the Overflow-
Count.
Underflow-Count: This parameter is used to decide when the bandwidth
should be adjusted when there is a sudden decrease in traffic
demand. This value indicates how many times consecutively, the
percentage or absolute difference between the current MaxAvgBw and
the current bandwidth reservation is greater than or equal to the
Underflow-Threshold value.
Underflow-Threshold: This parameter is used to decide when the
bandwidth should be adjusted when there is a sudden decrease in
traffic demand. If the percentage or absolute difference between
the current MaxAvgBw and the current bandwidth reservation is
greater than or equal to the threshold value, the underflow
condition is set to be met. The LSP bandwidth is adjusted to the
current bandwidth demand bypassing the Down-Adjustment-Interval if
the underflow condition is met consecutively for the Underflow-
Count.
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3. Requirements for PCEP Extensions
The PCEP extensions required for auto-bandwidth are summarized in the
following table.
+---------------------------------+---------------------------------+
| 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 |
| Delegation. | Initiation. |
| | |
+---------------------------------+---------------------------------+
Table 1: Auto-Bandwidth PCEP extensions
The 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 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
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intervention. The new bandwidth reservation is determined by
measuring the actual traffic flowing through the LSP. If the traffic
flowing through the LSP is lower than the configured or current
bandwidth of the LSP, the extra bandwidth is being reserved
needlessly and being wasted. Conversely, if the actual traffic
flowing through the LSP is higher than the configured or current
bandwidth of the LSP, it can potentially cause congestion or packet
loss in the network. With Auto-Bandwidth feature, the LSP bandwidth
is set to some arbitrary value (including zero) during initial setup
time, which will be periodically adjusted based on the actual
bandwidth demand. The bandwidth adjustment uses the make-before-
break (MBB) signaling method so that there is no disruption to the
traffic flow.
4.2. Auto-bandwidth Theory of Operation
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 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-
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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.
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, the two representations
help an operator to handle conditions when the bandwidth usage
becomes too large or too small. In any case, the auto-bandwidth
adjusted bandwidth is only reported to a PCE when MaxAvgBw crosses a
threshold.
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.
The PCEP protocol extensions for Auto-Bandwidth adjustments MUST NOT
be used if one or both PCEP Speakers have not included the "Auto-
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Bandwidth Capability" TLV in their respective OPEN message. If the
PCEP speaker that supports the extensions of this document but did
not advertise this capability, then upon receipt of AUTO-BANDWIDTH-
ATTRIBUTES TLV in LSPA object, it SHOULD generate a PCErr with error-
type 19 (Invalid Operation), error-value TBD4 (Auto-Bandwidth
capability was not advertised) and terminate the PCEP session.
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.
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 [I-D.ietf-pce-pce-initiated-lsp], 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.
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The TLV is encoded in all PCEP messages for the LSP while the auto-
bandwidth adjustment feature is enabled, the absence of the TLV
indicate 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 4 Adjustment-Threshold-Percentage sub-TLV
6 4 Down-Adjustment-Threshold sub-TLV
7 4 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 4 Overflow-Threshold-Percentage sub-TLV
12 8 Underflow-Threshold sub-TLV
13 4 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
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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
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, and the value comprises of 4-octet time
interval, the valid range is from 1 to 604800, in seconds. The
default value is 300 seconds. 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 specify the time interval for both upward and downward trend (Up-
Adjustment-Interval and Down-Adjustment-Interval). 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.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=2 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adjustment-Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Adjustment-Interval sub-TLV format
The Type is 2, Length is 4, and the value comprises of 4-octet time
interval, the valid range is from 1 to 604800, in seconds. The
default value is 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, and the value comprises of 4-octet time
interval, 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 specify 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 specify the threshold
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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.
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, and the value comprises of -
o Adjustment Threshold: The absolute Adjustment-Threshold bandwidth
value, encoded in IEEE floating point format (see
[IEEE.754.1985]), expressed in bytes per second. Refer to Section
3.1.2 of [RFC3471] for a table of commonly used values.
If the difference between the current MaxAvgBw and the current
bandwidth reservation is greater than or less than or equal to the
threshold value, the LSP bandwidth is adjusted to the current
bandwidth demand (MaxAvgBw). The default adjustment-threshold value
is not set.
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=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Percentage |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Adjustment-Threshold-Percentage sub-TLV format
The Type is 5, Length is 4, and the value comprises of -
o Reserved: SHOULD be set to zero on transmission and MUST be
ignored on receipt.
o Percentage: The Adjustment-Threshold value, encoded in percentage
(an integer from 0 to 100). If the percentage difference between
the current MaxAvgBw and the current bandwidth reservation is
greater than or less than or equal to the threshold percentage,
the LSP bandwidth is adjusted to the current bandwidth demand
(MaxAvgBw). The default value is 5 percent.
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, 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. 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).
The default value equals the adjustment-threshold.
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
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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=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Percentage |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Down-Adjustment-Threshold-Percentage sub-TLV format
The Type is 7, Length is 4, and the value comprises of -
o Reserved: SHOULD be set to zero on transmission and MUST be
ignored on receipt.
o Percentage: The Down-Adjustment-Threshold value, encoded in
percentage (an integer from 0 to 100). 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). The default value equals the adjustment-
threshold-percentage.
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, and the value comprises of 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.
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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, and the value comprises of 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
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. The default 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 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
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The Type is 10, Length is 8, and the value comprises of -
o Reserved: SHOULD be set to zero on transmission and MUST be
ignored on receipt.
o Count: The Overflow-Count value, encoded in integer. The value 0
is considered to be invalid. The number of consecutive samples
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
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=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Percentage | Reserved | Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Overflow-Threshold-Percentage sub-TLV format
The Type is 11, Length is 4, and the value comprises of -
o Percentage: The Overflow-Threshold value, encoded in percentage
(an integer from 0 to 100). If the percentage increase of the
current MaxAvgBw from the current bandwidth reservation is greater
than or equal to the threshold percentage, the overflow condition
is met.
o Reserved: SHOULD be set to zero on transmission and MUST be
ignored on receipt.
o Count: The Overflow-Count value, encoded in integer. The value 0
is considered to be invalid. The number of consecutive samples
for which the overflow condition MUST be met for the LSP bandwidth
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to be immediately adjusted to the current bandwidth demand,
bypassing the (up) adjustment-interval.
5.2.5.3. Underflow-Threshold sub-TLV
The Underflow-Threshold sub-TLV is used to decide if the bandwidth
should be adjusted immediately.
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, and the value comprises of -
o Reserved: SHOULD be set to zero on transmission and MUST be
ignored on receipt.
o Count: The Underflow-Count value, encoded in integer. The value 0
is considered to be invalid. The number of consecutive samples
for which the underflow condition MUST be met for the LSP
bandwidth to be immediately adjusted to the current bandwidth
demand, bypassing the 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
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=4 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Percentage | Reserved | Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Underflow-Threshold-Percentage sub-TLV format
The Type is 13, Length is 4, and the value comprises of -
o Percentage: The Underflow-Threshold value, encoded in percentage
(an integer from 0 to 100). If the percentage decrease of the
current MaxAvgBw from the current bandwidth reservation is greater
than or equal to the threshold percentage, the underflow condition
is met.
o Reserved: SHOULD be set to zero on transmission and MUST be
ignored on receipt.
o Count: The Underflow-Count value, encoded in integer. The value 0
is considered to be invalid. The number of consecutive samples
for which the underflow condition MUST be met for the LSP
bandwidth to be immediately adjusted to the current bandwidth
demand, bypassing the down-adjustment-interval.
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
[I.D.ietf-pce-pce-initiated-lsp].
For the PCE-Initiated LSP with Auto-Bandwidth feature enabled, AUTO-
BANDWIDTH-ATTRIBUTES TLV MUST be included in the LSPA object with the
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PCInitiate message.
The definition (RBNF) of the PCInitiate message
[I.D.ietf-pce-pce-initiated-lsp] 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 [I-D.ietf-pce-stateful-pce].
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
[I-D.ietf-pce-stateful-pce] is unchanged by this document.
5.6. The PCRpt Message
The PCRpt message [I-D.ietf-pce-stateful-pce] is a PCEP message sent
by a PCC to a PCE to report the status of one or more LSPs.
For PCE-Initiated LSPs [I.D.ietf-pce-pce-initiated-lsp], 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
[I-D.ietf-pce-stateful-pce] 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)
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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-
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
[I-D.ietf-pce-stateful-pce] 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 [I-D.ietf-pce-pceps].
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
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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
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.
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8. IANA Considerations
8.1. PCEP TLV Type Indicators
This document defines the following new PCEP TLVs; IANA is requested
to make the following allocations from 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 allocated only by an IETF Review action
[RFC5226]. 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
allocated only by an IETF Review action [RFC5226].
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]
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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) [I-D.ietf-pce-stateful-pce]; 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
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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.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", RFC 5440, March
2009.
[I-D.ietf-pce-stateful-pce] Crabbe, E., Minei, I., Medved, J., and
R. Varga, "PCEP Extensions for Stateful PCE", draft-ietf-
pce-stateful-pce (work in progress).
[I-D.ietf-pce-pce-initiated-lsp] Crabbe, E., Minei, I., Sivabalan,
S., and R. Varga, "PCEP Extensions for PCE-initiated LSP
Setup in a Stateful PCE Model", draft-ietf-pce-pce-
initiated-lsp (work in progress).
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.
[I-D.ietf-pce-pceps] Lopez, D., Dios, O., Wu, W., and D. Dhody,
"Secure Transport for PCEP", draft-ietf-pce-pceps (work in
progress).
[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
Dhody, et al. Expires October 19, 2017 [Page 26]
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(work in progress).
[I-D.gandhi-pce-pm] Gandhi, R., Wen, B., Barth, C., and D. Dhody,
"PCEP Extensions for Reporting MPLS-TE LSP Performance
Measurements", draft-gandhi-pce-pm (work in progress).
[IEEE.754.1985] Institute of Electrical and Electronics Engineers,
"Standard for Binary Floating-Point Arithmetic", IEEE
Standard 754, August 1985.
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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
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Authors' Addresses
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Udayasree Palle
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037
India
Email: 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
eBay
USA
Email: lufang@ebay.com
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