Internet DRAFT - draft-li-pce-sr-bidir-path
draft-li-pce-sr-bidir-path
PCE Working Group C. Li
Internet-Draft M. Chen
Intended status: Standards Track Huawei Technologies
Expires: August 9, 2020 W. Cheng
China Mobile
R. Gandhi
Cisco Systems, Inc.
Q. Xiong
ZTE Corporation
February 6, 2020
PCEP Extensions for Associated Bidirectional Segment Routing (SR) Paths
draft-li-pce-sr-bidir-path-07
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 Multiprotocol
Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths
(LSPs) using PCEP. Furthermore, PCEP can be used for computing paths
in Segment Routing (SR) TE networks.
This document defines PCEP extensions for grouping two reverse
unidirectional SR Paths into an Associated Bidirectional SR Path when
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 August 9, 2020.
Li, et al. Expires August 9, 2020 [Page 1]
Internet-Draft SR Bidirectional Association in PCEP February 2020
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. PCEP Extension for Bidirectional SR Path . . . . . . . . . . 4
3.1. Double-sided Bidirectional SR Path Association Group
Object . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Bidirectional Flag . . . . . . . . . . . . . . . . . . . . . 6
5. Procedures for Associated Bidirectional SR Path Computation . 6
5.1. PCE Initiated Associated Bidirectional SR Paths . . . . . 7
5.2. PCC Initiated Associated Bidirectional SR Paths . . . . . 7
5.3. Error Handling . . . . . . . . . . . . . . . . . . . . . 9
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 10
6.1. Huawei's Commercial Delivery . . . . . . . . . . . . . . 10
6.2. ZTE's Commercial Delivery . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7.1. Association Type . . . . . . . . . . . . . . . . . . . . 11
7.2. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. Manageability Considerations . . . . . . . . . . . . . . . . 12
9.1. Control of Function and Policy . . . . . . . . . . . . . 12
9.2. Information and Data Models . . . . . . . . . . . . . . . 12
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 12
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 12
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 12
9.6. Impact On Network Operations . . . . . . . . . . . . . . 12
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
12.1. Normative References . . . . . . . . . . . . . . . . . . 13
12.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
Li, et al. Expires August 9, 2020 [Page 2]
Internet-Draft SR Bidirectional Association in PCEP February 2020
1. Introduction
Segment routing (SR) [RFC8402] leverages the source routing and
tunneling paradigms. SR supports to steer packets into an explicit
forwarding path at the ingress node.
[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 Multiprotocol Label Switching (MPLS) as
well as Generalized MPLS (GMPLS) Traffic Engineering Label Switched
Path (TE LSP) characteristics.
[RFC8231] specifies a set of extensions to PCEP to enable stateful
control of TE LSPs within and across PCEP sessions in compliance with
[RFC4657]. It includes mechanisms to effect LSP State
Synchronization between PCCs and PCEs, delegation of control over
LSPs to PCEs, and PCE control of timing and sequence of path
computations within and across PCEP sessions. The model of operation
where LSPs are initiated from the PCE is described in [RFC8281].
[I-D.ietf-pce-segment-routing] 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 SR Paths.
[I-D.ietf-pce-association-group] 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, for
example primary and secondary LSP associations, and is equally
applicable to the active and passive modes of a Stateful PCE
[RFC8231] or a stateless PCE [RFC5440].
Currently, SR networks only support unidirectional paths. However,
bidirectional SR Paths are required in some networks, for example, in
mobile backhaul transport networks. The requirement of bidirectional
SR Path is specified in [I-D.ietf-spring-mpls-path-segment].
[I-D.ietf-pce-association-bidir] defines PCEP extensions for grouping
two reverse unidirectional MPLS 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.
This document extends the bidirectional association to segment
routing by specifying PCEP extensions for grouping two reverse
unidirectional SR Paths into a bidirectional SR Path.
Li, et al. Expires August 9, 2020 [Page 3]
Internet-Draft SR Bidirectional Association in PCEP February 2020
[I-D.ietf-pce-association-bidir] specifies the Double-sided
Bidirectional LSP Association procedure, where the PCE creates the
association and provisions at both endpoints, the RSVP-TE does the
signaling to the egress the status of the forward LSP and the ingress
about the reverse LSP. Thus, the both endpoints learn the reverse
LSPs forming the bidirectional LSP association. In case of SR, to
support the bidirectional path use-case, this is done using the PCEP
protocol. This is done so that both endpoints are aware of the the
unidirectional SR Path, as well as the status and other SR path
related information.
[I-D.li-pce-sr-path-segment] defines a procedure for Path Segment
Identifier (PSID) in PCEP for SR using PATH-SEGMENT TLV. The PSID
can be a Path Segment Identifier in SR-MPLS
[I-D.ietf-spring-mpls-path-segment]. The PSID can be used for an
associated bidirectional SR Path for identifying the SR Path.
2. Terminology
This document makes use of the terms defined in
[I-D.ietf-pce-segment-routing]. The reader is assumed to be familiar
with the terminology defined in [RFC5440], [RFC8231], [RFC8281],
[I-D.ietf-pce-association-group] 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 Extension for Bidirectional SR Path
As per [I-D.ietf-pce-association-group], LSPs are associated by
adding them to a common association group.
[I-D.ietf-pce-association-bidir] specifies PCEP extensions for
grouping two reverse unidirectional MPLS-TE LSPs into an Associated
Bidirectional LSP for both single-sided and double-sided initiation
cases by defining two new Bidirectional LSP Association Groups.
This document extends the procedure for associated bidirectional SR
Paths by defining a new bidirectional association group (Double-sided
Bidirectional SR Path Association Group). The document further
describes the mechanism for associating two unidirectional SR Paths
into a bidirectional SR Path. [I-D.li-pce-sr-path-segment] defines a
procedure for communicating Path Segment in PCEP for SR using PATH-
Li, et al. Expires August 9, 2020 [Page 4]
Internet-Draft SR Bidirectional Association in PCEP February 2020
SEGMENT TLV. The bidirectional SR Path can also use the PATH-SEGMENT
TLV.
Note that an association group is defined in this document to define
procedures specific to SR Paths (and the procedures are different
than the RSVP-TE bidirectional association groups defined in
[I-D.ietf-pce-association-bidir]).
3.1. Double-sided Bidirectional SR Path Association Group Object
As defined in [I-D.ietf-pce-association-bidir], two LSPs are
associated as a bidirectional MPLS-TE LSP by a common bidirectional
LSP association group. For associating two SR paths, this document
defines a new association group called 'Double-sided Bidirectional SR
Path Association Group' as follows:
o Association Type (TBD1 to be assigned by IANA) = Double-sided
Bidirectional SR Path Association Group
Similar to other bidirectional associations, this Association Type is
operator-configured in nature and statically created by the operator
on the PCEP peers. The paths belonging to this association is
conveyed via PCEP messages to the PCEP peer. Operator-configured
Association Range TLV [I-D.ietf-pce-association-group] MUST NOT be
sent for these Association Types, and MUST be ignored, so that the
entire range of association ID can be used for them. 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 SR Path Association
Group' can take the role of a forward or reverse SR Path and follow
the similar rules defined in [I-D.ietf-pce-association-bidir] for
LSPs.
o An SR Path (forward or reverse) can not be part of more than one
'Double-sided Bidirectional SR Path Association Group'.
o The endpoints of the SR Paths in this associations cannot be
different.
For describing the SR Paths in this association group, such as
direction and co-routed information, this association group reuses
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].
Li, et al. Expires August 9, 2020 [Page 5]
Internet-Draft SR Bidirectional Association in PCEP February 2020
4. Bidirectional Flag
As defined in [RFC5440], the B-flag in RP object MUST be set when the
PCC specifies that the path computation request relates to a
bidirectional TE LSP. In this document, the B-flag also MUST be set
when the PCC specifies that the path computation request relates to a
bidirectional SR Path. When a stateful PCE initiates or updates a
bidirectional SR Paths including LSPs and SR paths, the B-flag in SRP
object [I-D.ietf-pce-pcep-stateful-pce-gmpls] MAY be set as well.
5. Procedures for Associated Bidirectional SR Path Computation
Two unidirectional SR Paths can be associated by the association
group object as specified in [I-D.ietf-pce-association-group]. A
bidirectional LSP association group object is defined in
[I-D.ietf-pce-association-bidir] (for MPLS-TE). This document
extends these association mechanisms for bidirectional SR Paths. Two
SR Paths can be associated together by using the Bidirectional SR
Path Association Group defined in this document for PCEP messages.
The PATH-SEGMENT TLV [I-D.li-pce-sr-path-segment] SHOULD also be
included in the LSP object for these SR Paths to support required
use-cases.
For bidirectional SR Paths, there is a need to know the reverse
direction SR paths. The PCE SHOULD inform the reverse SR Paths to
the ingress PCCs and vice versa. 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 same association group). These PCInitiate message MUST NOT
trigger initiation of SR Paths. The reverse direction SR Path can be
used for several use-cases, such as directed BFD
[I-D.ietf-mpls-bfd-directed].
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. In
other words, the LSP will have a PLSP-ID A at the ingress node while
it will have the PLSP-ID B at the egress node. The PCE will maintain
the two PLSP-IDs for the same LSP. For instance, an ingress PCC
requests a bidirectional SR Path computation, and the PCE computes a
forward LSP1 with PLSP-ID say 100. The reverse LSP2 from the egress
to the ingress with PLSP-ID say 200 is allocated by the egress PCC.
Since the PLSP-ID space is independent at each PCC, the PLSP-ID
allocated by the egress PCC can not be used for the LSP at the
ingress PCC (PLSP-ID conflict may occur). Hence, the PCE needs to
allocate a PLSP-ID for LSP2 from the ingress PCC's PLSP-ID space ,
say 101. Similarly for LSP1, it has PLSP-ID 100 at the ingress, and
may have say PLSP-ID 201 at the egress node.
Li, et al. Expires August 9, 2020 [Page 6]
Internet-Draft SR Bidirectional Association in PCEP February 2020
5.1. PCE Initiated Associated Bidirectional SR Paths
As specified in [I-D.ietf-pce-association-group], Bidirectional SR
Path Association Group can be created by a Stateful PCE.
o Stateful PCE can create and update the forward and reverse SR
Paths independently for a 'Double-sided Bidirectional SR Path
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 [I-D.ietf-pce-association-group].
o The PATH-SEGMENT TLV SHOULD be included for each SR Path in the
LSP object.
o The reverse direction SR Path (LSP2(R) at node S, LSP1(R) at node
D) SHOULD be informed by PCE via PCInitiate message with the
matching association group.
+-----+
| PCE |
+-----+
PCInitiate/PCUpd: / \ PCInitiate/PCUpd:
Tunnel 1 (F) / \ Tunnel 2 (F)
(LSP1 (F), LSP2 (R)) / \ (LSP2 (F), LSP1 (R))
Association #1 / \ Association #1
/ \
v v
+-----+ LSP1 +-----+
| S |------------>| D |
| |<------------| |
+-----+ LSP2 +-----+
<no signaling>
Figure 1: PCE-Initiated Double-sided Bidirectional SR Path
with Forward and Reverse Direction SR Paths
5.2. PCC Initiated Associated Bidirectional SR Paths
As specified in [I-D.ietf-pce-association-group], Bidirectional SR
Path Association Group can also be created by a PCC.
Li, et al. Expires August 9, 2020 [Page 7]
Internet-Draft SR Bidirectional Association in PCEP February 2020
o PCC can create and update the forward and reverse SR Paths
independently for a 'Double-sided Bidirectional SR Path
Association Group'.
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 SR Path Association Group' via PCUpd message, using
the procedures described in [I-D.ietf-pce-association-group].
o The PATH-SEGMENT TLV MUST be handled as defined in
[I-D.li-pce-sr-path-segment].
o The reverse direction SR Path (LSP2(R) at node S, LSP1(R) at node
D) SHOULD be informed by PCE via PCInitiate message with the
matching association group.
Li, et al. Expires August 9, 2020 [Page 8]
Internet-Draft SR Bidirectional Association in PCEP February 2020
+-----+
| PCE |
+-----+
Report/Delegate: ^ ^ Report/Delegate:
Tunnel 1 (F) / \ Tunnel 2 (F)
(LSP1 (F)) / \ (LSP2 (F))
Association #2 / \ Association #2
/ \
/ \
+-----+ LSP1 +-----+
| S |------------>| D |
| |<------------| |
+-----+ LSP2 +-----+
<no signaling>
Figure 2a: Step 1: PCC-Initiated Double-sided Bidirectional SR Path
with Forward Direction SR Paths
+-----+
| PCE |
+-----+
PCUpd/PCInitiate: / \ PCUpd/PCInitiate:
Tunnel 1 (F) / \ Tunnel 2 (F)
(LSP1 (F), LSP2 (R)) / \ (LSP2 (F), LSP1 (R))
Association #2 / \ Association #2
/ \
v v
+-----+ LSP1 +-----+
| S |------------>| D |
| |<------------| |
+-----+ LSP2 +-----+
<no signaling>
Figure 2b: Step 2: PCE-Upd/Initiated Double-sided Bidirectional Path
Along with Reverse Direction SR Paths
5.3. Error Handling
The error handling as described in section 5.5 of
[I-D.ietf-pce-association-bidir] continue to apply.
The PCEP Path Setup Type (PST) MUST be set to 'TE Path is Setup using
Segment Routing' [I-D.ietf-pce-segment-routing] for the LSP belonging
to the 'Double-sided Bidirectional SR Path Association Group'. In
case a PCEP speaker receives a different PST value for this
association group, it MUST send a PCErr message with Error-Type = 29
Li, et al. Expires August 9, 2020 [Page 9]
Internet-Draft SR Bidirectional Association in PCEP February 2020
(Early allocation by IANA) (Association Error) and Error-Value = TBD2
(Bidirectional LSP Association - Path Setup Type Mismatch).
6. 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".
6.1. 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
6.2. ZTE's Commercial Delivery
o Organization: ZTE
Li, et al. Expires August 9, 2020 [Page 10]
Internet-Draft SR Bidirectional Association in PCEP February 2020
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
7. IANA Considerations
7.1. Association Type
This document defines a new Association Type for the Association
Object defined [I-D.ietf-pce-association-group]. IANA is requested
to make the assignment of a value for the sub-registry "ASSOCIATION
Type Field" (to be created in [I-D.ietf-pce-association-group]), as
follows:
Value Name Reference
-------------------------------------------------------------------
TBD1 Double-sided Bidirectional This document
SR Path Association Group
7.2. PCEP Errors
This document defines new Error value for Error Type 29 (Association
Error). IANA is requested to allocate new Error value within the
"PCEP-ERROR Object Error Types and Values" sub-registry of the PCEP
Numbers registry, as follows:
Error Type Description Reference
-------------------------------------------------------------------
29 Association Error
Error value: TBD2 This document
Bidirectional LSP Association -
Path Setup Type Mismatch
8. Security Considerations
The security considerations described in [RFC5440], [RFC8231],
[RFC8281], and [I-D.ietf-pce-segment-routing] apply to the extensions
defined in this document as well.
A new Association Type for the Association Object, 'Double-sided
Associated Bidirectional SR Path Association Group' is introduced in
Li, et al. Expires August 9, 2020 [Page 11]
Internet-Draft SR Bidirectional Association in PCEP February 2020
this document. Additional security considerations related to LSP
associations due to a malicious PCEP speaker is described in
[I-D.ietf-pce-association-group] and apply to this Association Type.
Hence, securing the PCEP session using Transport Layer Security (TLS)
[RFC8253] is recommended.
9. 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.
9.1. 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].
9.2. Information and Data Models
[RFC7420] describes the PCEP MIB, there are no new MIB Objects
defined for Bidirectional SR Path associations. The PCEP YANG module
[I-D.ietf-pce-pcep-yang] defines data model for Bidirectional SR Path
associations.
9.3. 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].
9.4. 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 [I-D.ietf-pce-segment-routing] .
9.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
9.6. Impact On Network Operations
Mechanisms defined in [RFC5440], [RFC8231], and
[I-D.ietf-pce-segment-routing] also apply to PCEP extensions defined
in this document.
Li, et al. Expires August 9, 2020 [Page 12]
Internet-Draft SR Bidirectional Association in PCEP February 2020
10. Contributors
The following people have substantially contributed to this document:
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
11. Acknowledgments
Many thanks to Marina Fizgeer for detailed review and comments.
12. References
12.1. 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>.
Li, et al. Expires August 9, 2020 [Page 13]
Internet-Draft SR Bidirectional Association in PCEP February 2020
[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>.
[I-D.ietf-pce-association-group]
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)", draft-ietf-pce-association-group-10 (work in
progress), August 2019.
[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-05 (work in progress),
February 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-12 (work in
progress), October 2019.
[I-D.li-pce-sr-path-segment]
Li, C., Chen, M., Cheng, W., Dong, J., Li, Z., Gandhi, R.,
and Q. Xiong, "Path Computation Element Communication
Protocol (PCEP) Extension for Path Segment in Segment
Routing (SR)", draft-li-pce-sr-path-segment-08 (work in
progress), August 2019.
Li, et al. Expires August 9, 2020 [Page 14]
Internet-Draft SR Bidirectional Association in PCEP February 2020
12.2. Informative References
[RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol Generic
Requirements", RFC 4657, DOI 10.17487/RFC4657, September
2006, <https://www.rfc-editor.org/info/rfc4657>.
[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>.
[I-D.ietf-pce-segment-routing]
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "PCEP Extensions for Segment Routing",
draft-ietf-pce-segment-routing-16 (work in progress),
March 2019.
[I-D.ietf-mpls-bfd-directed]
Mirsky, G., Tantsura, J., Varlashkin, I., and M. Chen,
"Bidirectional Forwarding Detection (BFD) Directed Return
Path", draft-ietf-mpls-bfd-directed-13 (work in progress),
December 2019.
[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-01 (work in progress),
September 2019.
Li, et al. Expires August 9, 2020 [Page 15]
Internet-Draft SR Bidirectional Association in PCEP 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-13 (work in progress), October 2019.
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
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
Li, et al. Expires August 9, 2020 [Page 16]
