One document matched: draft-dhody-pce-stateful-pce-auto-bandwidth-03.xml
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<rfc ipr="trust200902" category="std" docName="draft-dhody-pce-stateful-pce-auto-bandwidth-03" obsoletes="" updates="" submissionType="IETF" xml:lang="en">
<front>
<title abbrev="AUTO-BW">PCEP Extensions for MPLS-TE LSP Automatic Bandwidth Adjustment with stateful PCE</title>
<author initials="D" surname="Dhody" fullname="Dhruv Dhody">
<organization>Huawei Technologies India Pvt Ltd</organization>
<address>
<postal>
<street>Leela Palace</street>
<city>Bangalore</city>
<region>Karnataka</region>
<code>560008</code>
<country>INDIA</country>
</postal>
<email>dhruv.ietf@gmail.com</email>
</address>
</author>
<author initials="U" surname="Palle" fullname="Udayasree Palle">
<organization>Huawei Technologies India Pvt Ltd</organization>
<address>
<postal>
<street>Leela Palace</street>
<city>Bangalore</city>
<region>Karnataka</region>
<code>560008</code>
<country>INDIA</country>
</postal>
<email>udayasree.palle@huawei.com</email>
</address>
</author>
<date month="January" year="2014" />
<area>Routing</area>
<workgroup>PCE Working Group</workgroup>
<abstract>
<t>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 extensions described in
<xref target="STATEFUL-PCE"/> provide stateful control of
Multiprotocol Label Switching (MPLS) Traffic Engineering
Label Switched Paths (TE LSP) via PCEP, for a model where
the PCC delegates control over one or more locally
configured LSPs to the PCE.</t>
<t>This document describes the automatic bandwidth adjustment
of such LSPs under the Active Stateful PCE model.</t>
</abstract>
</front>
<middle>
<section title="Introduction" toc="default">
<t><xref target="RFC5440"/> describes the Path Computation
Element Protocol (PCEP) as the communication between a Path
Computation Client (PCC) and a Path Control Element (PCE),
or between PCE and PCE, enabling computation of Multiprotocol
Label Switching (MPLS) for Traffic Engineering Label Switched
Path (TE LSP).</t>
<t><xref target="STATEFUL-PCE"/> specifies extensions to PCEP
to enable stateful control of MPLS TE LSPs. In this document focus
is on Active Stateful PCE where LSPs are configured on the PCC
and control over them is delegated to the PCE.</t>
<t>Over time, based on the varying traffic pattern, an LSP
established with certain bandwidth may require to adjust the
reserved bandwidth over time automatically. Ingress Label Switch
Router (LSR) samples the traffic rate at each sample-interval to
determine the traffic information as Maximum Average Bandwidth
(MaxAvgBw). Further adjustment to the reserved bandwidth should be
made at every adjustment-interval automatically.</t>
<t>Enabling Auto-Bandwidth on a LSP results in the LSP automatically
adjusting its bandwidth based on the actual traffic flowing through
the LSP. A LSP can therefore be setup with some arbitrary (or zero)
bandwidth value such that the LSP automatically monitors the traffic
flow and adjusts its bandwidth every adjustment-interval period.
The bandwidth adjustment uses the make-before-break signaling method
so that there is no interruption to traffic flow. This is described
in detail in <xref target="sec_auto"/>.</t>
<t><xref target="STATEFUL-PCE-APP"/> describes the usecase for
auto-bandwidth adjustment for passive and active stateful PCE. Active
stateful PCE can use information such as historical trending data,
application-specific information about expected demands or policy
information, as well as knowledge of the actual desired flow volumes
to make smarter bandwidth adjustment to delegated LSPs.</t>
<t>This document defines extensions needed to support Auto-Bandwidth
feature along with mechanism to provide traffic information of the
LSPs in a stateful PCE model using PCEP.</t>
<t>This document does not exclude use of any other
mechanism employed by stateful PCE to learn real time traffic information
etc. But at the same time, using the same protocol (PCEP in this case) for
updating and reporting the LSP parameters as well as to support automatic
bandwidth adjustment is operationally beneficial.</t>
<section title="Requirements Language" toc="default">
<t>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 <xref target="RFC2119"/>.</t>
</section>
</section>
<section title="Terminology" toc="default">
<t>The following terminology is used in this document.</t>
<t>
<list style="hanging">
<t hangText="Active Stateful PCE:">PCE that uses tunnel state
information learned from PCCs to optimize path computations.
Additionally, it actively updates tunnel parameters in those
PCCs that delegated control over their tunnels to the PCE.</t>
<t hangText="Delegation:">:An operation to grant a PCE temporary
rights to modify a subset of tunnel parameters on one or more
PCC's tunnels. Tunnels are delegated from a PCC to a PCE.</t>
<t hangText="PCC:">Path Computation Client: any client application
requesting a path computation to be performed by a Path
Computation Element.</t>
<t hangText="PCE:">Path Computation Element. An entity (component,
application, or network node) that is capable of computing a
network path or route based on a network graph and applying
computational constraints.</t>
<t hangText="TE LSP:">Traffic Engineering Label Switched Path.</t>
</list>
</t>
<t>Note the additional terms defined in <xref target="sec_auto"/>.</t>
</section>
<section title="Motivation" toc="default">
<t>An active stateful PCE can update the bandwidth for a delegated
LSP via mechanisms described in <xref target="STATEFUL-PCE"/>.
Note that further extension are needed because of following
reasons: </t>
<t>
<list style="numbers">
<t>To identify the LSPs that would like to use this feature.
Not all LSPs in some deployments would like there bandwidth
to be dependent on the live traffic but be constant as set by
the operator. Incase of PCC initiated LSP, they would be
configured at PCC and PCEP should support a mechanism to
identify the LSP with auto bandwidth feature enabled at the PCE.</t>
<t>Further for LSP with auto bandwidth feature enabled, operator should
be able to specify the knobs to control this feature like
the bandwidth-range etc and PCEP should support their encoding.</t>
<t>PCC would need to report the live traffic information using
the same protocol (PCEP in this case) making the network
operations easier.</t>
</list>
</t>
<t>Extensions as specified in this document is one of the way for
PCE to learn this information. But at the same time a stateful
PCE MAY choose to learn this
information from other means like management, performance tools.</t>
</section>
<section title="Architectural Overview" toc="default">
<section title="Auto-Bandwidth Overview" toc="default" anchor="sec_auto">
<t>Auto-Bandwidth feature allows an LSP to automatically and dynamically
adjust its reserved bandwidth over time, i.e. without network operator
intervention. The bandwidth adjustment uses the make-before-break adaptive
signaling method so that there is no interruption to traffic flow.</t>
<t>The new bandwidth reservation is determined by sampling the actual traffic
flowing through the LSP. If the traffic flowing through the LSP is lower than
the configured or current bandwidth of the LSP, the extra bandwidth is being
reserved needlessly and being wasted. Conversely, if the actual traffic flowing
through the LSP is higher than the configured or current bandwidth of the LSP,
it can potentially cause congestion or packet loss. With Auto-Bandwidth feature,
the LSP bandwidth can be set to some arbitrary value (even zero) during initial
setup time, and it will be periodically adjusted over time based on the actual
bandwidth requirement.</t>
<t>Note the following terms:</t>
<t>
<list style="hanging">
<t hangText="Maximum Average Bandwidth (MaxAvgBw):">The maximum average
bandwidth is the unit to measure the current traffic demand between a
time interval. This is the maximum value of the averaged traffic pattern
in a particular time interval.</t>
<t hangText="Sample-Interval:">The time interval in which the traffic
rate (MaxAvgBw) is collected as a sample.</t>
<t hangText="Adjustment-Interval:">The time interval in which the
bandwidth adjustment should be made based on the MaxAvgBw.</t>
<t hangText="Minimum Bandwidth:">The minimum bandwidth that should
be reserved for the LSP.</t>
<t hangText="Maximum Bandwidth:">The maximum bandwidth that can be
reserved for the LSP.</t>
<t hangText="Report-Threshold:">This value indicates when the MaxAvgBw
must be reported to stateful PCE via PCRpt message. Only if the percentage
difference between the current MaxAvgBw and the last MaxAvgBw is greater
than or equal to the threshold percentage the LSP bandwidth is reported to
PCE.</t>
<t hangText="Adjust-Threshold:">This value indicates when the bandwidth
must be adjusted. Only if the percentage difference between the current
MaxAvgBw and the current bandwidth allocation is greater than or equal
to the threshold percentage the LSP bandwidth is adjusted to the current
bandwidth demand.</t>
</list>
</t>
</section>
<section title="Deploying Auto-Bandwidth Feature" toc="default">
<t>The traffic rate is repeatedly sampled at each sample-interval
(which can be configured by the user and the default value as 5 minutes).
The sampled traffic rates are accumulated over the adjustment-interval
period (which can be configured by the user and the default value as
24 hours).</t>
<t>The ingress LSR reports the traffic information to the stateful PCE
via the PCRpt message, to avoid multiple reports, the Report-Threshold
percentage is used. Only if the percentage difference between the current
MaxAvgBw and the last MaxAvgBw is greater than or equal to the threshold
percentage the LSP bandwidth is reported to PCE.</t>
<t>Stateful PCE will adjust the bandwidth of the LSP to the highest sampled
traffic rate amongst the set of samples taken over the adjustment-interval.
Note that the highest sampled traffic rate could be higher or lower than
the current LSP bandwidth. Only if the current MaxAvgBw and the current
bandwidth allocation is greater than or equal to the Adjust-Threshold percentage
the LSP bandwidth is adjusted to the current bandwidth demand.</t>
<t>Also to avoid multiple LSP re-signaling, sometimes operator set up longer
adjustment intervals. However long adjustment-interval can also result in
an undesirable effect of masking sudden changes in traffic patterns. To avoid
this, the stateful PCE MAY pre-maturely expire the adjustment-interval to
accommodate sudden bursts in traffic.</t>
</section>
</section>
<section title="Extensions to the PCEP" toc="default">
<section title="AUTO-BANDWIDTH-ATTRIBUTE TLV" toc="default">
<t>The AUTO-BANDWIDTH-ATTRIBUTE TLV can be included as an optional TLV in the
LSP object as described in <xref target="STATEFUL-PCE"/>. Whenever the LSP
with Auto-Bandwidth feature enabled is delegated,
AUTO-BANDWIDTH-ATTRIBUTE TLV MUST be carried in PCRpt message.</t>
<t>The format of the AUTO-BANDWIDTH-ATTRIBUTE TLV is shown in the following figure:</t>
<figure title="AUTO-BANDWIDTH-ATTRIBUTE TLV format" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
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=[TBD] | Length=12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Threshold | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
<t>The type of the TLV is [TBD] and it has a fixed length of 12 octets.</t>
<t>The value contains the following fields:</t>
<t>
<list style="hanging">
<t hangText="Minimum Bandwidth (32 bits):">The minimum bandwidth
allowed is encoded in IEEE floating point format (see
<xref target="IEEE.754.1985"/>), expressed in bytes per second.
Refer to Section 3.1.2 of <xref target="RFC3471"/> for a table of
commonly used values.</t>
<t hangText="Maximum Bandwidth (32 bits):">The maximum bandwidth
allowed is encoded in IEEE floating point format (see
<xref target="IEEE.754.1985"/>), expressed in bytes per second.
Refer to Section 3.1.2 of <xref target="RFC3471"/> for a table of
commonly used values.</t>
<t hangText="Threshold (8 bits):">The Adjust-Threshold value is
encoded in percentage. Only if the percentage difference between
the current MaxAvgBw and the current bandwidth allocation is
greater than or equal to the threshold percentage the LSP
bandwidth is adjusted to the current bandwidth demand.</t>
<t hangText="Reserved (24 bits):">These bits MUST be set to
zero on transmission and MUST be ignored on receipt.</t>
</list>
</t>
<t>If the above parameters are not specified by the user, based
on the local policy at Ingress (PCC) the default value can be
encoded. </t>
<t>If no default value is specified at Ingress, value 'zero'
can be encoded for the particular field. The stateful PCE can
then apply its own default value based on the local policy.</t>
</section>
<section title="BANDWIDTH Object" toc="default">
<t>As per <xref target="RFC5440"/>, the BANDWIDTH object is
defined with two Object-Type values:</t>
<t>
<list style="symbols">
<t>Requested Bandwidth: BANDWIDTH Object-Type is 1.</t>
<t>Re-optimization Bandwidth: Bandwidth of an existing TE LSP
for which a reoptimization is requested. BANDWIDTH Object-Type
is 2.</t>
</list>
</t>
<t>The new BANDWIDTH object type 3 [TBD] is used to specify the
MaxAvgBw determined from the existing TE LSP Traffic flow at every
sample-interval. The Report-Threshold percentage is used to
determine if there is a need to report the current MaxAvgBw.</t>
</section>
<section title="The PCRpt Message" toc="default">
<t>When the delegated LSP is enabled with the Auto-Bandwidth
adjustment feature, a PCC MAY include the BANDWIDTH object of type
3 [TBD] in the PCRpt message. The definition of the PCRpt message
(see <xref target="STATEFUL-PCE"/>) is unchanged.</t>
<t>When LSP is delegated to a PCE for the very first time, BANDWIDTH
object of type 1 is used to specify the requested bandwidth in the
PCRpt message. To report the traffic flow information (as the MaxAvgBw)
the BANDWIDTH object of type 3 [TBD] is encoded in further PCRpt meessage.</t>
</section>
</section>
<section title="Security Considerations" toc="default">
<t>This document does not introduce any new security concerns beside those in
<xref target="STATEFUL-PCE"/>.</t>
</section>
<section title="Manageability Considerations" toc="default">
<section title="Control of Function and Policy" toc="default">
<t>The Auto-Bandwidth feature MUST BE controlled per tunnel at Ingress
(PCC), the values for parameters like sample-interval, adjustment-interval,
minimum-bandwidth, maximum-bandwidth, report-threshold, adjust-threshold
SHOULD BE configurable by an operator.</t>
</section>
<section title="Information and Data Models" toc="default">
<t><xref target="PCEP-MIB"/> describes the PCEP MIB, there are no new MIB Objects
for this document.</t>
</section>
<section title="Liveness Detection and Monitoring" toc="default">
<t>Mechanisms defined in this document do not imply any new liveness detection
and monitoring requirements in addition to those already listed in
<xref target="RFC5440"/>.</t>
</section>
<section title="Verify Correct Operations" toc="default">
<t>Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
<xref target="RFC5440"/>.</t>
</section>
<section title="Requirements On Other Protocols" toc="default">
<t>Mechanisms defined in this document do not imply any new requirements
on other protocols.</t>
</section>
<section title="Impact On Network Operations" toc="default">
<t>Mechanisms defined in this document do not have any impact on
network operations in addition to those already listed in
<xref target="RFC5440"/>.</t>
</section>
</section>
<section title="IANA Considerations" toc="default">
<section title="PCEP TLV Type Indicators" toc="default">
<t>This document defines the following new PCEP TLVs; IANA is
requested to make the following allocations from this registry.</t>
<t>
<figure title="" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
Value Meaning Reference
TBD AUTO-BANDWIDTH-ATTRIBUTE [This I.D.]
]]></artwork>
</figure>
</t>
</section>
<section title="BANDWIDTH Object" toc="default">
<t>This document defines new object type for the BANDWIDTH object;
IANA is requested to make the following allocations from this registry.</t>
<t>
<figure title="" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
Object-Class Value Name Reference
5 BANDWIDTH [This I.D.]
Object-Type
3: MaxAvgBw determined from
the existing TE LSP Traffic
flow.
]]></artwork>
</figure>
</t>
</section>
</section>
<section title="Acknowledgments" toc="default">
<t>We would like to thank Venugopal Reddy, Reeja Paul, Sandeep Boina
and Avantika for their useful comments and suggestions.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.2119.xml" ?>
</references>
<references title="Informative References">
<?rfc include="reference.RFC.3471.xml" ?>
<?rfc include="reference.RFC.5440.xml" ?>
<!--IEEE.754.1985-->
<reference anchor="IEEE.754.1985">
<front>
<title>Standard for Binary Floating-Point Arithmetic</title>
<author>
<organization>Institute of Electrical and Electronics Engineers</organization>
</author>
<date month="August" year="1985"/>
</front>
<seriesInfo name="IEEE" value="Standard 754"/>
</reference>
<!--STATEFUL-PCE-->
<reference anchor="STATEFUL-PCE">
<front>
<title>PCEP Extensions for Stateful PCE (draft-ietf-pce-stateful-pce)</title>
<author initials="E" surname="Crabbe" fullname="Crabbe E">
<organization />
</author>
<author initials="J" surname="Medved" fullname="Medved J">
<organization />
</author>
<author initials="I" surname="Minei" fullname="Minei I">
<organization />
</author>
<author initials="R" surname="Varga," fullname="Varga R">
<organization />
</author>
<date month="October" year="2013" />
</front>
</reference>
<!--STATEFUL-PCE-APP-->
<reference anchor="STATEFUL-PCE-APP">
<front>
<title>Applicability of Stateful Path Computation Element (PCE) (draft-ietf-pce-stateful-pce-app)</title>
<author initials="X" surname="Zhang" fullname="Zhang X">
<organization />
</author>
<author initials="I" surname="Minei" fullname="Minei I">
<organization />
</author>
<date month="September" year="2013" />
</front>
</reference>
<!--PCEP-MIB-->
<reference anchor="PCEP-MIB">
<front>
<title>PCE communication protocol(PCEP) Management Information Base [draft-ietf-pce-pcep-mib]</title>
<author initials="A S" surname="Kiran Koushik" fullname="Kiran Koushik A S">
<organization />
</author>
<author initials="E" surname="Stephan" fullname="Stephan E">
<organization />
</author>
<author initials="Q" surname="Zhao" fullname="Quintin Zhao">
<organization />
</author>
<author initials="D" surname="King" fullname="Daniel King">
<organization />
</author>
<author initials="J" surname="Hardwick" fullname="John Hardwick">
<organization />
</author>
<date month="January" year="2014" />
</front>
</reference>
</references>
<section title="Contributor Addresses" toc="default">
<t>
<figure title="" suppress-title="false" align="left" alt="" width="" height="">
<artwork xml:space="preserve" name="" type="" align="left" alt="" width="" height=""><![CDATA[
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
US
Phone: +1 972 509 5599 x2240
Fax: +1 469 229 5397
EMail: leeyoung@huawei.com
]]></artwork>
</figure>
</t>
</section>
</back>
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