Network Working Group M. Koldychev
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track S. Sivabalan
Expires: December 25, 2020 Ciena Corporation
T. Saad
V. Beeram
Juniper Networks, Inc.
H. Bidgoli
Nokia
B. Yadav
Ciena
June 23, 2020
PCEP Extensions for Signaling Multipath Information
draft-koldychev-pce-multipath-02
Abstract
Current PCEP standards allow only one intended and/or actual path to
be present in a PCEP report or update. Applications that require
multipath support such as SR Policy require an extension to allow
signaling multiple intended and/or actual paths within a single PCEP
message. This document introduces such an extension. Encoding of
multiple intended and/or actual paths is done by encoding multiple
Explicit Route Objects (EROs) and/or multiple Record Route Objects
(RROs). A special separator object is defined in this document, to
facilitate this. This mechanism is applicable to SR-TE and RSVP-TE
and is dataplane agnostic.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 25, 2020.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Terms and Abbreviations . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Signaling Multiple Segment-Lists of an SR Candidate-Path 4
3.2. Splitting of Requested Bandwidth . . . . . . . . . . . . 4
3.3. Providing Backup path for Protection . . . . . . . . . . 4
4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 4
4.1. Multipath Capability TLV . . . . . . . . . . . . . . . . 4
4.2. Path Attributes Object . . . . . . . . . . . . . . . . . 5
4.3. Multipath Weight TLV . . . . . . . . . . . . . . . . . . 6
4.4. Multipath Backup TLV . . . . . . . . . . . . . . . . . . 7
5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Signaling Multiple Paths for Loadbalancing . . . . . . . 8
5.2. Signaling Multiple Paths for Protection . . . . . . . . . 9
6. PCEP Message Extensions . . . . . . . . . . . . . . . . . . . 9
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. SR Policy Candidate-Path with Multiple Segment-Lists . . 10
7.2. Two Primary Paths Protected by One Backup Path . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. Security Considerations . . . . . . . . . . . . . . . . . . . 12
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 12
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
12.1. Normative References . . . . . . . . . . . . . . . . . . 13
12.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
Path Computation Element (PCE) Communication Protocol (PCEP)
[RFC5440] enables the communication between a Path Computation Client
(PCC) and a Path Control Element (PCE), or between two PCEs based on
the PCE architecture [RFC4655].
PCEP Extensions for the Stateful PCE Model [RFC8231] describes a set
of extensions to PCEP that enable active control of Multiprotocol
Label Switching Traffic Engineering (MPLS-TE) and Generalized MPLS
(GMPLS) tunnels. [RFC8281] describes the setup and teardown of PCE-
initiated LSPs under the active stateful PCE model, without the need
for local configuration on the PCC, thus allowing for dynamic
centralized control of a network.
PCEP Extensions for Segment Routing [RFC8664] specifies extensions to
the Path Computation Element Protocol (PCEP) that allow a stateful
PCE to compute and initiate Traffic Engineering (TE) paths, as well
as for a PCC to request a path subject to certain constraint(s) and
optimization criteria in SR networks.
Segment Routing Policy for Traffic Engineering
[I-D.ietf-spring-segment-routing-policy] details the concepts of SR
Policy and approaches to steering traffic into an SR Policy. In
particular, it describes the SR candidate-path as a collection of one
or more Segment-Lists. The current PCEP standards only allow for
signaling of one Segment-List per Candidate-Path. PCEP extension to
support Segment Routing Policy Candidate Paths
[I-D.barth-pce-segment-routing-policy-cp] specifically avoids
defining how to signal multipath information, and states that this
will be defined in another document.
This document defines the required extensions that allow the
signaling of multipath information via PCEP.
2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
[RFC2119].
2.1. Terms and Abbreviations
The following terms are used in this document:
PCEP Tunnel:
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The object identified by the PLSP-ID, see
[I-D.koldychev-pce-operational] for more details.
3. Motivation
This extension is motivated by the use-cases described below.
3.1. Signaling Multiple Segment-Lists of an SR Candidate-Path
The Candidate-Path of an SR Policy is the unit of report/update in
PCEP, see [I-D.barth-pce-segment-routing-policy-cp]. Each Candidate-
Path can contain multiple Segment-Lists and each Segment-List is
encoded by one SR-ERO object. However, each PCEP LSP can contain
only a single SR-ERO object, which prevents us from encoding multiple
Segment- Lists within the same SR Candidate-Path.
With the help of the protocol extensions defined in this document,
this limitation is overcome.
3.2. Splitting of Requested Bandwidth
A PCC may request a path with 100 Gbps of bandwidth, but all links in
the network have only 50 Gbps capacity. The PCE can return two
paths, that can each carry 50 Gbps. The PCC can then equally or
unequally split the incoming 100 Gbps of traffic among the two 50
Gbps paths. Section 4.3 introduces a new TLV that carries the path
weight that allows for distribution of incoming traffic on to the
multiple paths.
3.3. Providing Backup path for Protection
It is desirable for the PCE to compute and signal to the PCC a backup
path that is used to protect a primary path.
When multipath is used, a backup path may protect one or more primary
paths. For this reason, a primary and backup path identifiers are
needed to indicate which backup path(s) protect which primary
path(s). Section 4.4 introduces a new TLV that carries the required
information.
4. Protocol Extensions
4.1. Multipath Capability TLV
We define the MULTIPATH-CAP TLV that MAY be present in the OPEN
object and/or the LSP object. The purpose of this TLV is two-fold:
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1. From PCC: it tells how many multipaths the PCC can install in
forwarding.
2. From PCE: it tells that the PCE supports this standard and how
many multipaths the PCE can compute.
Only the first instance of this TLV can be processed, subsequent
instances SHOULD be ignored.
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Multipaths | Reserved |B|W|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: MULTIPATH-CAP TLV format
Type: TBD1 for "MULTIPATH-CAP" TLV.
Length: 4.
Number of Multipaths: the maximum number of multipaths that a PCE can
return. The value 0 indicates unlimited number.
B-flag: whether MULTIPATH-BACKUP-TLV is supported.
W-flag: whether MULTIPATH-WEIGHT-TLV is supported.
Reserved: zero on transmit, ignore on receipt.
4.2. Path Attributes Object
We define the PATH-ATTRIB object that is used to carry per-path
information and to act as a separator between several ERO/RRO objects
in the intended-path/actual-path RBNF element. The PATH-ATTRIB
object always precedes the ERO/RRO that it applies to. If multiple
ERO/RRO objects are present, then each ERO/RRO object MUST be
preceded by an PATH-ATTRIB object that describes it.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Oper|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Optional TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: PATH-ATTRIB object format
Flags: to be extended in the future.
Oper: operational state of the path, same values as the identically
named field in the LSP object.
Path ID: 4-octet identifier that identifies a path in the set of
multiple paths.
4.3. Multipath Weight TLV
We define the MULTIPATH-WEIGHT TLV that MAY be present in the PATH-
ATTRIB object.
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: MULTIPATH-WEIGHT TLV format
Type: TBD2 for "MULTIPATH-WEIGHT" TLV.
Length: 4.
Weight: weight of this path within the multipath, if W-ECMP is
desired. The fraction of flows a specific ERO/RRO carries is derived
from the ratio of its weight to the sum of all other multipath ERO/
RRO weights.
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4.4. Multipath Backup TLV
This document introduces a new MULTIPATH-BACKUP TLV that is optional
and can be present in the PATH-ATTRIB object.
This TLV is used to indicate the presence of a backup path that is
used for protection in case of failure of the primary path. The
format of the MULTIPATH-BACKUP TLV is:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Backup Path Count | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Backup Path ID 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Backup Path ID 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Backup Path ID n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: MULTIPATH-BACKUP TLV format
Type: TBD3 for "MULTIPATH-BACKUP" TLV
Length: variable - multiple of 4-octets
Backup Path Count: Number of backup path(s).
Flags:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|B| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
B: If set, indicates a pure backup path. This is a path that only
carries rerouted traffic after the protected path fails. If this
flag is not set, or if the MULTIPATH-BACKUP TLV is not carried in
the PATH-ATTRIB object of an ERO or SERO, then the path is assumed
to be primary that carries normal traffic.
Backup Path ID(s): a series of 4-octet identifier(s) that identify
the backup path(s) in the set that protect this primary path.
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5. Operation
When the PCC wants to indicate to the PCE that it wants to get
multipaths instead of a single path, it can do one or both of the
following:
1. Send the MULTIPATH-CAP TLV in the OPEN object during session
establishment. This applies to all PCEP Tunnels on the PCC,
unless overridden by PCEP Tunnel specific information.
2. Send the MULTIPATH-CAP TLV in the LSP object for a particular
PCEP Tunnel in the PCRpt message. This applies to the specified
PCEP Tunnel and overrides the information from the OPEN object.
When PCE computes the path for a PCEP Tunnel, it MUST NOT return more
multipaths than the corresponding value of "Number of Multipaths"
from the MULTIPATH-CAP TLV. If this TLV is absent (from both OPEN
and LSP objects), then the "Number of Multipaths" is assumed to be 1.
If the PCE supports this standard, then it MUST include the
MULTIPATH-CAP TLV in the OPEN object. This tells the PCC that it can
report multiple ERO/RRO objects to this PCE. If the PCE does not
include the MULTIPATH-CAP TLV in the OPEN object, then the PCC MUST
assume that the PCE does not support this standard and fall back to
reporting only a single ERO/RRO.
The Path ID of each ERO/RRO MUST be unique within that LSP. If a
PCEP speaker detects that there are two paths with the same Path ID,
then the PCEP speaker SHOULD send PCError message with Error-Type = 1
("Reception of an invalid object") and Error-Value = TBD4
("Conflicting Path ID").
5.1. Signaling Multiple Paths for Loadbalancing
The PATH-ATTRIB object can be used to signal multiple path(s) and
indicate (un)equal loadbalancing amongst the set of multipaths. In
this case, the PATH-ATTRIB is populated for each ERO or SERO as
follows:
1. The PCE assigns a unique Path ID to each ERO or SERO path and
populates it inside the PATH-ATTRIB object. The Path ID is
unique within the context of a PLSP or PCEP Tunnel.
2. The MULTIPATH-WEIGHT TLV MAY be carried inside the PATH-ATTRIB
object. A weight is populated to reflect the relative loadshare
that is to be carried by the path. If the MULTIPATH-WEIGHT is
not carried inside a PATH-ATTRIB object, the default weight 1
MUST be assumed when computing the loadshare.
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3. The fraction of flows carried by a specific primary path is
derived from the ratio of its weight to the sum of all other
multipath weights.
5.2. Signaling Multiple Paths for Protection
The PATH-ATTRIB object can be used to describe a set of backup
path(s) protecting a primary path. In this case, the PATH-ATTRIB is
populated for each ERO or SERO as follows:
1. The PCE assigns a unique Path ID to each ERO or SERO path and
populates it inside the PATH-ATTRIB object. The Path ID is
unique within the context of a PLSP or PCEP Tunnel.
2. The MULTIPATH-BACKUP TLV MUST be added inside the PATH-ATTRIB
object for each ERO or SERO that is protected. The backup path
ID(s) are populated in the MULTIPATH-BACKUP TLV to reflect the
set of backup path(s) protecting the primary path. The Length
field and Backup Path Number in the MULTIPATH-BACKUP are updated
according to the number of backup path ID(s) included.
3. The MULTIPATH-BACKUP TLV MAY be added inside the PATH-ATTRIB
object for each ERO or SERO that is unprotected. In this case,
MULTIPATH-BACKUP does not carry any backup path IDs in the TLV.
If the path acts as a pure backup - i.e. the path only carries
rerouted traffic after the protected path(s) fail- then the B
flag MUST be set.
Note that if a given path has the B-flag set, then there MUST be some
other path within the same LSP that uses the given path as a backup.
If this condition is violated, then the PCEP speaker SHOULD send a
PCError message with Error-Type = 10 ("Reception of an invalid
object") and Error-Value = TBD5 ("No primary path for pure backup").
Note that a given PCC may not support certain backup combinations,
such as a backup path that is itself protected by another backup
path, etc. If a PCC is not able to implement a requested backup
scenario, the PCC SHOULD send a PCError message with Error-Type = 19
("Invalid Operation") and Error-Value = TBD6 ("Not supported path
backup").
6. PCEP Message Extensions
The RBNF of PCReq, PCRep, PCRpt, PCUpd and PCInit messages currently
use intended-path and/or actual-path:
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<intended-path> ::= (<ERO>|<SERO>)
[<intended-path>]
<actual-path> ::= (<RRO>|<SRRO>)
[<actual-path>]
In this standard, we extend these two elements:
<intended-path> ::= [<PATH-ATTRIB>](<ERO>|<SERO>)
[<intended-path>]
<actual-path> ::= [<PATH-ATTRIB>](<RRO>|<SRRO>)
[<actual-path>]
7. Examples
7.1. SR Policy Candidate-Path with Multiple Segment-Lists
Consider how the following sample SR Policy, taken from
[I-D.ietf-spring-segment-routing-policy], would be represented in a
PCRpt message.
SR policy POL1 <headend, color, endpoint>
Candidate-path CP1 <protocol-origin = 20, originator =
100:1.1.1.1, discriminator = 1>
Preference 200
Weight W1, SID-List1 <SID11...SID1i>
Weight W2, SID-List2 <SID21...SID2j>
Candidate-path CP2 <protocol-origin = 20, originator =
100:2.2.2.2, discriminator = 2>
Preference 100
Weight W3, SID-List3 <SID31...SID3i>
Weight W4, SID-List4 <SID41...SID4j>
As specified in [I-D.barth-pce-segment-routing-policy-cp], CP1 and
CP2 are signaled as separate state-report elements and each has a
unique PLSP-ID, assigned by the PCC. Let us assign PLSP-ID 100 to
CP1 and PLSP-ID 200 to CP2.
The state-report for CP1 can be encoded as:
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<state-report> =
<LSP PLSP_ID=100>
<ASSOCIATION>
<END-POINT>
<PATH-ATTRIB Path_ID=1 <WEIGHT-TLV Weight=W1>>
<ERO SID-List1>
<PATH-ATTRIB Path_ID=2 <WEIGHT-TLV Weight=W2>>
<ERO SID-List2>
The state-report for CP2 can be encoded as:
<state-report> =
<LSP PLSP_ID=200>
<ASSOCIATION>
<END-POINT>
<PATH-ATTRIB Path_ID=1 <WEIGHT-TLV Weight=W3>>
<ERO SID-List3>
<PATH-ATTRIB Path_ID=2 <WEIGHT-TLV Weight=W4>>
<ERO SID-List4>
The above sample state-report elements only specify the minimum
mandatory objects, of course other objects like SRP, LSPA, METRIC,
etc., are allowed to be inserted.
Note that the syntax
<PATH-ATTRIB Path_ID=1 <WEIGHT-TLV Weight=W1>>
, simply means that this is PATH-ATTRIB object with Path ID field set
to "1" and with a MULTIPATH-WEIGHT TLV carrying weight of "W1".
7.2. Two Primary Paths Protected by One Backup Path
Suppose there are 3 paths: A, B, C. Where A,B are primary and C is
to be used only when A or B fail. Suppose the Path IDs for A, B, C
are respectively 1, 2, 3. This would be encoded in a state-report
as:
<state-report> =
<LSP>
<ASSOCIATION>
<END-POINT>
<PATH-ATTRIB Path_ID=1 <BACKUP-TLV B=0, Backup_Paths=[3]>>
<ERO A>
<PATH-ATTRIB Path_ID=2 <BACKUP-TLV B=0, Backup_Paths=[3]>>
<ERO B>
<PATH-ATTRIB Path_ID=3 <BACKUP-TLV B=1, Backup_Paths=[]>>
<ERO C>
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Note that the syntax
<PATH-ATTRIB Path_ID=1 <BACKUP-TLV B=0, Backup_Paths=[3]>>
, simply means that this is PATH-ATTRIB object with Path ID field set
to "1" and with a MULTIPATH-BACKUP TLV that has B-flag cleared and
contains a single backup path with Backup Path ID of 3.
8. IANA Considerations
IANA is requested to make the assignment of a new value for the
existing "PCEP TLV Type Indicators" registry as follows:
+------------+-----------------------------------+-----------------+
| TLV Type | TLV Name | Reference |
| Value | | |
+------------+-----------------------------------+-----------------+
| TBD1 | MULTIPATH-CAP | This document |
+------------+-----------------------------------+-----------------+
| TBD2 | MULTIPATH-WEIGHT | This document |
+------------+-----------------------------------+-----------------+
| TBD3 | MULTIPATH-BACKUP | This document |
+------------+-----------------------------------+-----------------+
IANA is requested to make the assignment of a new value for the
existing "PCEP-ERROR Object Error Types and Values" registry as
follows:
+------------+-----------------------------------+-----------------+
| Error-Type | Error-Value | Reference |
+------------+-----------------------------------+-----------------+
| 10 | TBD4 - Conflicting Path ID | This document |
+------------+-----------------------------------+-----------------+
| 10 | TBD5 - No primary path for pure | This document |
| | backup | |
+------------+-----------------------------------+-----------------+
| 19 | TBD6 - Not supported path backup | This document |
+------------+-----------------------------------+-----------------+
9. Security Considerations
None at this time.
10. Acknowledgement
Thanks to Dhruv Dhody for ideas and discussion.
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11. Contributors
Andrew Stone
Nokia
Email: andrew.stone@nokia.com
12. References
12.1. Normative References
[I-D.barth-pce-segment-routing-policy-cp]
Koldychev, M., Sivabalan, S., Barth, C., Peng, S., and H.
Bidgoli, "PCEP extension to support Segment Routing Policy
Candidate Paths", draft-barth-pce-segment-routing-policy-
cp-06 (work in progress), June 2020.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-07 (work in progress),
May 2020.
[I-D.koldychev-pce-operational]
Koldychev, M., Sivabalan, S., Negi, M., Achaval, D., and
H. Kotni, "PCEP Operational Clarification", draft-
koldychev-pce-operational-01 (work in progress), February
2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
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[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>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "Path Computation Element Communication
Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
DOI 10.17487/RFC8664, December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
12.2. Informative References
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
Authors' Addresses
Mike Koldychev
Cisco Systems, Inc.
Email: mkoldych@cisco.com
Siva Sivabalan
Ciena Corporation
Email: ssivabal@ciena.com
Tarek Saad
Juniper Networks, Inc.
Email: tsaad@juniper.net
Vishnu Pavan Beeram
Juniper Networks, Inc.
Email: vbeeram@juniper.net
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Internet-Draft PCEP Extensions for Multipath June 2020
Hooman Bidgoli
Nokia
Email: hooman.bidgoli@nokia.com
Bhupendra Yadav
Ciena
Email: byadav@ciena.com
Koldychev, et al. Expires December 25, 2020 [Page 15]