PCE Working Group C. Li
Internet-Draft M. Chen
Intended status: Standards Track Huawei Technologies
Expires: March 19, 2021 W. Cheng
China Mobile
R. Gandhi
Cisco Systems, Inc.
Q. Xiong
ZTE Corporation
September 15, 2020
PCEP Extensions for Associated Bidirectional Segment Routing (SR) Paths
draft-ietf-pce-sr-bidir-path-03
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.
Segment routing (SR) leverages the source routing and tunneling
paradigms. The Stateful PCEP extensions allow stateful control of
Segment Routing Traffic Engineering (TE) Paths. Furthermore, PCEP
can be used for computing SR TE paths in the network.
This document defines PCEP extensions for grouping two unidirectional
SR Paths (one in each direction in the network) into a single
Associated Bidirectional SR Path. The mechanisms defined in this
document can also be applied using a Stateful PCE for both PCE-
Initiated and PCC-Initiated LSPs, as well as when using a Stateless
PCE.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 19, 2021.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Double-sided Bidirectional with Reverse LSP Association
Group . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.1. Bidirectional LSP Association Group TLV . . . . . . . 6
4. PCEP Procedures . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. PCE Initiated Associated Bidirectional SR Paths . . . . . 7
4.2. PCC Initiated Associated Bidirectional SR Paths . . . . . 8
4.3. Stateless PCE . . . . . . . . . . . . . . . . . . . . . . 10
4.4. Bidirectional (B) Flag . . . . . . . . . . . . . . . . . 10
4.5. State Synchronization . . . . . . . . . . . . . . . . . . 11
4.6. Error Handling . . . . . . . . . . . . . . . . . . . . . 11
5. Implementation Status . . . . . . . . . . . . . . . . . . . . 11
5.1. Huawei's Commercial Delivery . . . . . . . . . . . . . . 12
5.2. ZTE's Commercial Delivery . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. Manageability Considerations . . . . . . . . . . . . . . . . 12
7.1. Control of Function and Policy . . . . . . . . . . . . . 13
7.2. Information and Data Models . . . . . . . . . . . . . . . 13
7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 13
7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 13
7.5. Requirements On Other Protocols . . . . . . . . . . . . . 13
7.6. Impact On Network Operations . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8.1. Association Type . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . 14
9.2. Informative References . . . . . . . . . . . . . . . . . 15
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 16
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Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
Segment routing (SR) [RFC8402] leverages the source routing and
tunneling paradigms. SR supports steering packets onto an explicit
forwarding path at the ingress node. SR is specified for
unidirectional paths. However, some applications require
bidirectional paths in SR networks, for example, in mobile backhaul
transport networks. The requirement for bidirectional SR Paths is
specified in [I-D.ietf-spring-mpls-path-segment].
[RFC5440] describes the Path Computation Element (PCE) Communication
Protocol (PCEP). PCEP enables the communication between a Path
Computation Client (PCC) and a PCE, or between PCE and PCE, for the
purpose of computation of Traffic Engineering (TE) Label Switched
Paths (LSP). [RFC8231] specifies a set of extensions to PCEP to
enable stateful control of TE LSPs within and across PCEP sessions.
The mode of operation where LSPs are initiated from the PCE is
described in [RFC8281].
[RFC8408] specifies extensions to the Path Computation Element
Protocol (PCEP) [RFC5440] for SR networks, that allow a stateful PCE
to compute and initiate SR TE paths, as well as a PCC to request,
report or delegate them.
[RFC8697] introduces a generic mechanism to create a grouping of LSPs
which can then be used to define associations between a set of LSPs
and/or a set of attributes, and is equally applicable to the active
and passive modes of a Stateful PCE [RFC8231] or a stateless PCE
[RFC5440].
[I-D.ietf-pce-association-bidir] defines PCEP extensions for grouping
two unidirectional RSVP-TE LSPs into an Associated Bidirectional LSP
when using a Stateful PCE for both PCE-Initiated and PCC-Initiated
LSPs as well as when using a Stateless PCE. It specifies the
procedure for 'Double-sided Bidirectional LSP Association', where the
PCE creates the association and provisions the forward LSPs at their
ingress nodes. The RSVP-TE signals the forward LSPs to the egress
nodes. Thus, both endpoints learn the reverse LSPs forming the
bidirectional LSP association.
This document extends the bidirectional LSP association to SR by
specifying PCEP extensions for grouping two unidirectional SR Paths
into a bidirectional SR Path. For bidirectional SR, there are use-
cases such as directed BFD [I-D.ietf-mpls-bfd-directed] and SR
Performance Measurement (PM) [I-D.gandhi-spring-stamp-srpm] those
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require PCC to be aware of the reverse direction SR Path. For such
use-cases, the reverse SR Paths are also communicated to the ingress
nodes using the PCEP extensions defined in this document. This
allows both endpoints to be aware of the SR Paths in both directions,
including their status and all other path related information.
Associating an unidirectional SR Path with a reverse direction
unidirectional RSVP-TE LSP to form a bidirectional LSP and vice
versa, are outside the scope of this document.
Note that the procedure for using the association group defined in
this document is specific to the associated bidirectional SR Paths.
The procedure for this association group is different than the
bidirectional association groups defined in
[I-D.ietf-pce-association-bidir] for associated bidirectional RSVP-TE
LSPs.
An SR Policy may contain one or more Candidate-Paths (CPs), each
Candidate-Path may contain one or more Segment Lists (SLs)
[I-D.ietf-spring-segment-routing-policy]. Recall that in PCEP, an
LSP identifies a Candidate-Path as described in
[I-D.ietf-pce-segment-routing-policy-cp]. Two unidirectional
Candidate-Paths containing a single Segment List (two unidirectional
Segment Lists) are associated to form a bidirectional Candidate-Path
using the procedures defined in this document. Association of two
unidirectional Candidate-Paths containing multiple Segment Lists to
form a bidirectional Candidate-Path are outside the scope of this
document.
2. Terminology
This document makes use of the terms defined in [RFC8408]. The
reader is assumed to be familiar with the terminology defined in
[RFC5440], [RFC8231], [RFC8281], [RFC8697], and
[I-D.ietf-pce-association-bidir].
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. PCEP Extensions
As per [RFC8697], TE LSPs are associated by adding them to a common
association group by a PCEP peer. [I-D.ietf-pce-association-bidir]
uses the association group object and the procedures as specified in
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[RFC8697] to group two unidirectional RSVP-TE LSPs. Similarly, two
SR Paths can also be associated using similar technique. This
document extends these association mechanisms for bidirectional SR
Paths. Two unidirectional SR Paths (one in each direction in the
network) can be associated together by using the association group
defined in this document for PCEP messages.
[I-D.ietf-pce-sr-path-segment] defines a mechanism for communicating
Path Segment Identifier (PSID) in PCEP for SR. The PSID is defined
for SR-MPLS in [I-D.ietf-spring-mpls-path-segment]. The PSID can be
used for identifying an SR Path of an associated bidirectional SR
Path. The PATH-SEGMENT TLV MAY be included for each SR Path in the
LSP object to support required use-cases. The PATH-SEGMENT TLV MUST
be handled as defined in [I-D.ietf-pce-sr-path-segment] and is not
modified for associated bidirectional SR Path.
3.1. Double-sided Bidirectional with Reverse LSP Association Group
For associating two unidirectional SR Paths, this document defines a
new Association Type called 'Double-sided Bidirectional with Reverse
LSP Association Group' for Association Group Object (Class-Value 40)
as follows:
o Association Type (TBD1 to be assigned by IANA) = Double-sided
Bidirectional with Reverse LSP Association Group
Similar to RSVP-TE bidirectional LSP associations, this Association
Type is also operator-configured in nature and statically created by
the operator on the PCEP peers. 'Operator-configured Association
Range' TLV (Value 29) [RFC8697] MUST NOT be sent for this Association
Type, and MUST be ignored, so that the entire range of association ID
can be used for it.
The handling of the Association ID, Association Source, optional
Global Association Source and optional Extended Association ID in
this association are set in the same way as
[I-D.ietf-pce-association-bidir].
A member of the 'Double-sided Bidirectional with Reverse LSP
Association Group' can take the role of a forward or reverse
direction SR Path and follow the similar rules defined in
[I-D.ietf-pce-association-bidir] for LSPs.
o An SR Path (forward or reverse) cannot be part of more than one
'Double-sided Bidirectional with Reverse LSP Association Group'.
o The endpoints of the SR Paths in 'Double-sided Bidirectional with
Reverse LSP Association Group' cannot be different.
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3.1.1. Bidirectional LSP Association Group TLV
In 'Double-sided Bidirectional with Reverse LSP Association Group',
for properties such as forward and reverse direction and co-routed
path, it uses the Bidirectional LSP Association Group TLV defined in
[I-D.ietf-pce-association-bidir]. All fields and processing rules
are as per [I-D.ietf-pce-association-bidir].
4. PCEP Procedures
For a Bidirectional SR Path, an ingress PCC is aware of the forward
direction SR Path beginning from itself to the egress PCC using the
existing PCEP procedures. For the use-cases which require the
ingress PCC to be aware of the reverse direction SR Path, PCE informs
the reverse SR Path to the ingress PCC. To achieve this, a
PCInitiate message for the reverse SR Path is sent to the ingress PCC
and a PCInitiate message for the forward SR Path is sent to the
egress PCC (with the matching association group). These PCInitiate
message MUST NOT trigger initiation of SR Paths on PCCs.
For a bidirectional LSP computation when using both direction LSPs on
a node, the same LSP would need to be identified using 2 different
PLSP-IDs based on the PCEP session to the ingress or the egress node.
Note that the PLSP-ID space is independent at each PCC, the PLSP-ID
allocated by the egress PCC cannot be used for the LSP at the ingress
PCC (PLSP-ID conflict may occur). As per normal PCInitiate
operations, PCC assigns the PLSP-IDs for the local LSPs. Hence, when
the PCE notifies an ingress PCC of the reverse LSP, it does so by
using PCInitiate operations and sets PLSP-ID to zero and sets the R
bit in the Bidirectional LSP Association Group TLV in the association
object to indicate that this PCInitiate LSP is a reverse LSP. The
PCC upon receiving the PCInitiate MUST locally assign a new PLSP-ID
and it MUST issue a PCRpt to PCE for this LSP containing the new
PLSP-ID. This reverse direction LSP MUST NOT be instantiated on the
PCC.
In other words, a given LSP will be identified by PLSP-ID A at the
ingress node while it will be identified by PLSP-ID B at the egress
node. The PCE will maintain two PLSP-IDs for the same LSP. For
example, ingress PCC1 may report to PCE an LSP1 with PLSP-ID 100.
Egress PCC2 may report to PCE an LSP2 with PLSP-ID 200. Both of
these LSPs are part of a bidirectional association. When PCE
notifies PCC1 of the reverse direction LSP2, it does so by sending a
PCInitiate to PCC1 with PLSP-ID set to zero and R bit set in the
Bidirectional LSP Association Group TLV. PCC1 upon reception of this
generates a new PLSP-ID (example PLSP-ID 300) and issues a PCRpt to
PCE. Thus there would two PLSP-ID associated for LSP2 (300 at PCC1
and 200 at PCC2).
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4.1. PCE Initiated Associated Bidirectional SR Paths
As specified in [RFC8697], Associated Bidirectional SR Paths can be
created by a Stateful PCE as shown in Figure 1.
o Stateful PCE can create and update the forward and reverse SR
Paths independently for 'Double-sided Bidirectional with Reverse
LSP Association Group'.
o Stateful PCE can establish and remove the association relationship
on a per SR Path basis.
o Stateful PCE can create and update the SR Path and the association
on a PCC via PCInitiate and PCUpd messages, respectively, using
the procedures described in [RFC8697].
o The reverse direction SR Path (LSP2(R) at node S, LSP1(R) at node
D as shown in Figure 1) SHOULD be informed by the PCE via
PCInitiate message with the matching association group for the
use-cases which require the PCC to be aware of the reverse
direction SR Path.
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+-----+
| PCE |
+-----+
PCInitiate: / \ PCInitiate:
Tunnel 1 (F) / \ Tunnel 2 (F)
LSP1 (F,0), LSP2 (R,0) / \ LSP2 (F,0), LSP1 (R,0)
Association #1 / \ Association #1
/ \
v v
+-----+ LSP1 +-----+
| S |------------>| D |
| |<------------| |
+-----+ LSP2 +-----+
<no signaling>
Figure 1a: PCE-Initiated Associated Bidirectional SR Path
with Forward and Reverse Direction SR Paths
+-----+
| PCE |
+-----+
PCRpt: ^ ^ PCRpt:
Tunnel 1 (F) / \ Tunnel 2 (F)
LSP1 (F,100), LSP2 (R,300) / \ LSP2 (F,200), LSP1 (R,400)
Association #1 / \ Association #1
/ \
/ \
+-----+ LSP1 +-----+
| S |------------>| D |
| |<------------| |
+-----+ LSP2 +-----+
<no signaling>
Figure 1b: PCC-Reported Bidirectional SR Path
with Forward and Reverse Direction SR Paths
4.2. PCC Initiated Associated Bidirectional SR Paths
As specified in [RFC8697], Associated Bidirectional SR Paths can also
be created by a PCC as shown in Figure 2a and 2b.
o PCC can create and update the forward SR Path and update the
reverse SR Path independently for a 'Double-sided Bidirectional
with Reverse LSP Association Group'.
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o PCC cannot instantiate a reverse SR Path in a bidirectional SR
Path.
o PCC can establish and remove the association relationship on a per
SR Path basis.
o PCC MUST report the change in the association group of an SR Path
to PCE(s) via PCRpt message.
o PCC can report the forward and reverse SR Paths independently to
PCE(s) via PCRpt message.
o PCC can delegate the forward and reverse SR Paths independently to
a Stateful PCE, where PCE would control the SR Paths.
o Stateful PCE can update the SR Paths in the 'Double-sided
Bidirectional with Reverse LSP Association Group' via PCUpd
message, using the procedures described in [RFC8697].
o The reverse direction SR Path (LSP2(R) at node S, LSP1(R) at node
D as shown in Figure 2b) SHOULD be informed by the PCE via
PCInitiate message with the matching association group for the
use-cases which require the PCC to be aware of the reverse
direction SR Path.
+-----+
| PCE |
+-----+
Report/Delegate: ^ ^ Report/Delegate:
Tunnel 1 (F) / \ Tunnel 2 (F)
LSP1 (F,100) / \ LSP2 (F,200)
Association #2 / \ Association #2
/ \
/ \
+-----+ LSP1 +-----+
| S |------------>| D |
| |<------------| |
+-----+ LSP2 +-----+
<no signaling>
Figure 2a: Step 1: PCC-Initiated Associated Bidirectional SR
Path with Forward Direction SR Paths
+-----+
| PCE |
+-----+
PCInitiate: / \ PCInitiate:
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Tunnel 1 (F) / \ Tunnel 2 (F)
LSP1 (F,100), LSP2 (R,0) / \ LSP2 (F,200), LSP1 (R,0)
Association #2 / \ Association #2
/ \
v v
+-----+ LSP1 +-----+
| S |------------>| D |
| |<------------| |
+-----+ LSP2 +-----+
<no signaling>
Figure 2b: Step 2: PCE-Initiated Associated Bidirectional SR
Path with Reverse Direction SR Paths
+-----+
| PCE |
+-----+
PCRpt: ^ ^ PCRpt:
Tunnel 1 (F) / \ Tunnel 2 (F)
LSP1 (F,100), LSP2 (R,300) / \ LSP2 (F,200), LSP1 (R,400)
Association #2 / \ Association #2
/ \
/ \
+-----+ LSP1 +-----+
| S |------------>| D |
| |<------------| |
+-----+ LSP2 +-----+
<no signaling>
Figure 2c: Step 3: PCC-Reported Associated Bidirectional SR
Path with Reverse Direction SR Paths
4.3. Stateless PCE
As defined in [I-D.ietf-pce-association-bidir], for a stateless PCE,
it might be useful to associate a path computation request to an
association group, thus enabling it to associate a common set of
configuration parameters or behaviors with the request. A PCC can
request co-routed or non-co-routed forward and reverse direction
paths from a stateless PCE for a bidirectional SR association group.
4.4. Bidirectional (B) Flag
The Bidirectional (B) flag in Request Parameters (RP) object
[RFC5440] and Stateful PCE Request Parameter (SRP) object
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[I-D.ietf-pce-pcep-stateful-pce-gmpls] follow the procedure defined
in [I-D.ietf-pce-association-bidir].
4.5. State Synchronization
During state synchronization, a PCC MUST report all the existing
Bidirectional Association Groups to the Stateful PCE as per
[RFC8697]. After the state synchronization, the PCE MUST remove all
stale Bidirectional Association Groups.
4.6. Error Handling
The error handling as described in section 5.7 of
[I-D.ietf-pce-association-bidir] continue to apply.
The PCEP Path Setup Type (PST) for SR is set to 'TE Path is Setup
using Segment Routing' [RFC8408]. If a PCEP speaker receives a
different PST value for 'Double-sided Bidirectional with Reverse LSP
Association Group' and it does not support; it MUST send a PCErr
message with Error-Type = 26 (Association Error) and Error-Value =
'Bidirectional LSP Association - Path Setup Type Not Supported'
defined in [I-D.ietf-pce-association-bidir].
5. Implementation Status
[Note to the RFC Editor - remove this section before publication, as
well as remove the reference to [RFC7942].
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
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5.1. Huawei's Commercial Delivery
The feature is developing based on Huawei VRP8.
o Organization: Huawei
o Implementation: Huawei's Commercial Delivery implementation based
on VRP8.
o Description: The implementation is under development.
o Maturity Level: Product
o Contact: tanren@huawei.com
5.2. ZTE's Commercial Delivery
o Organization: ZTE
o Implementation: ZTE's Commercial Delivery implementation based on
Rosng v8.
o Description: The implementation is under development.
o Maturity Level: Product
o Contact: zhan.shuangping@zte.com.cn
6. Security Considerations
The security considerations described in [RFC5440], [RFC8231],
[RFC8281], and [RFC8408] apply to the extensions defined in this
document as well.
A new Association Type for the Association Object, 'Double-sided
Bidirectional with Reverse LSP Association Group' is introduced in
this document. Additional security considerations related to LSP
associations due to a malicious PCEP speaker is described in
[RFC8697] and apply to this Association Type. Hence, securing the
PCEP session using Transport Layer Security (TLS) [RFC8253] is
recommended.
7. Manageability Considerations
All manageability requirements and considerations listed in
[RFC5440], [RFC8231], and [RFC8281] apply to PCEP protocol extensions
defined in this document. In addition, requirements and
considerations listed in this section apply.
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7.1. Control of Function and Policy
The mechanisms defined in this document do not imply any control or
policy requirements in addition to those already listed in [RFC5440],
[RFC8231], and [RFC8281].
7.2. Information and Data Models
[RFC7420] describes the PCEP MIB, there are no new MIB Objects
defined for 'Double-sided Bidirectional with Reverse LSP Association
Groups'. The PCEP YANG module [I-D.ietf-pce-pcep-yang] defines data
model for Associated Bidirectional SR Paths.
7.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already
listed in [RFC5440], [RFC8231], and [RFC8281].
7.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440], [RFC8231], and [RFC8408].
7.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
7.6. Impact On Network Operations
Mechanisms defined in [RFC5440], [RFC8231], and [RFC8408] also apply
to PCEP extensions defined in this document.
8. IANA Considerations
8.1. Association Type
This document defines a new Association Type for the Association
Object (Class Value 40) defined [RFC8697]. IANA is requested to make
the assignment of a type for the sub-registry "ASSOCIATION Type" as
follows:
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Type Name Reference
-------------------------------------------------------------------
TBD1 Double-sided Bidirectional with Reverse This document
LSP Association Group
9. References
9.1. Normative References
[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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "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>.
[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>.
[RFC8697] Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Dhody, D., and Y. Tanaka, "Path Computation Element
Communication Protocol (PCEP) Extensions for Establishing
Relationships between Sets of Label Switched Paths
(LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020,
<https://www.rfc-editor.org/info/rfc8697>.
[I-D.ietf-pce-association-bidir]
Gandhi, R., Barth, C., and B. Wen, "PCEP Extensions for
Associated Bidirectional Label Switched Paths (LSPs)",
draft-ietf-pce-association-bidir-07 (work in progress),
September 2020.
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[I-D.ietf-pce-sr-path-segment]
Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong,
"Path Computation Element Communication Protocol (PCEP)
Extension for Path Segment in Segment Routing (SR)",
draft-ietf-pce-sr-path-segment-01 (work in progress), May
2020.
9.2. Informative References
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[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, DOI 10.17487/RFC7420, December 2014,
<https://www.rfc-editor.org/info/rfc7420>.
[RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J.
Hardwick, "Conveying Path Setup Type in PCE Communication
Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408,
July 2018, <https://www.rfc-editor.org/info/rfc8408>.
[I-D.ietf-mpls-bfd-directed]
Mirsky, G., Tantsura, J., Varlashkin, I., and M. Chen,
"Bidirectional Forwarding Detection (BFD) Directed Return
Path for MPLS Label Switched Paths (LSPs)", draft-ietf-
mpls-bfd-directed-15 (work in progress), August 2020.
[I-D.gandhi-spring-stamp-srpm]
Gandhi, R., Filsfils, C., Voyer, D., Chen, M., and B.
Janssens, "Performance Measurement Using Simple TWAMP
(STAMP) for Segment Routing Networks", draft-gandhi-
spring-stamp-srpm-02 (work in progress), August 2020.
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[I-D.ietf-spring-mpls-path-segment]
Cheng, W., Li, H., Chen, M., Gandhi, R., and R. Zigler,
"Path Segment in MPLS Based Segment Routing Network",
draft-ietf-spring-mpls-path-segment-02 (work in progress),
February 2020.
[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-14 (work in progress), July 2020.
[I-D.ietf-pce-pcep-stateful-pce-gmpls]
Lee, Y., Zheng, H., Dios, O., Lopezalvarez, V., and Z.
Ali, "Path Computation Element (PCE) Protocol Extensions
for Stateful PCE Usage in GMPLS-controlled Networks",
draft-ietf-pce-pcep-stateful-pce-gmpls-13 (work in
progress), April 2020.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-08 (work in progress),
July 2020.
[I-D.ietf-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-ietf-pce-segment-routing-policy-
cp-00 (work in progress), June 2020.
Acknowledgments
Many thanks to Marina Fizgeer, Adrian Farrel, Andrew Stone, and Tarek
Saad for the detailed review of this document and providing many
useful comments.
Contributors
The following people have substantially contributed to this document:
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Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Zhenbin Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: jie.dong@huawei.com
Authors' Addresses
Cheng Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: chengli13@huawei.com
Mach(Guoyi) Chen
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: Mach.chen@huawei.com
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Weiqiang Cheng
China Mobile
China
Email: chengweiqiang@chinamobile.com
Rakesh Gandhi
Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
Quan Xiong
ZTE Corporation
China
Email: xiong.quan@zte.com.cn
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