draft-ietf-pce-sr-bidir-path-00.txt   draft-ietf-pce-sr-bidir-path-01.txt 
PCE Working Group C. Li PCE Working Group C. Li
Internet-Draft M. Chen Internet-Draft M. Chen
Intended status: Standards Track Huawei Technologies Intended status: Standards Track Huawei Technologies
Expires: August 10, 2020 W. Cheng Expires: August 17, 2020 W. Cheng
China Mobile China Mobile
R. Gandhi R. Gandhi
Cisco Systems, Inc. Cisco Systems, Inc.
Q. Xiong Q. Xiong
ZTE Corporation ZTE Corporation
February 7, 2020 February 14, 2020
PCEP Extensions for Associated Bidirectional Segment Routing (SR) Paths PCEP Extensions for Associated Bidirectional Segment Routing (SR) Paths
draft-ietf-pce-sr-bidir-path-00 draft-ietf-pce-sr-bidir-path-01
Abstract Abstract
The Path Computation Element Communication Protocol (PCEP) provides The Path Computation Element Communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path mechanisms for Path Computation Elements (PCEs) to perform path
computations in response to Path Computation Clients (PCCs) requests. computations in response to Path Computation Clients (PCCs) requests.
The Stateful PCE extensions allow stateful control of Multiprotocol Segment routing (SR) leverages the source routing and tunneling
Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths paradigms. The Stateful PCEP extensions allow stateful control of
(LSPs) using PCEP. Furthermore, PCEP can be used for computing paths Segment Routing (SR) Traffic Engineering (TE) Paths. Furthermore,
in Segment Routing (SR) TE networks. PCEP can be used for computing SR TE paths in the network.
This document defines PCEP extensions for grouping two reverse This document defines PCEP extensions for grouping two unidirectional
unidirectional SR Paths into an Associated Bidirectional SR Path when SR Paths (one in each direction in the network) into a single
using a Stateful PCE for both PCE-Initiated and PCC-Initiated LSPs as Associated Bidirectional SR Path. The mechanisms defined in this
well as when using a Stateless PCE. 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 Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 10, 2020. This Internet-Draft will expire on August 17, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 25 skipping to change at page 2, line 25
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. PCEP Extension for Bidirectional SR Path . . . . . . . . . . 4 3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Double-sided Bidirectional SR Path Association Group 3.1. Double-sided Bidirectional SR Path Association Group . . 5
Object . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1.1. Bidirectional LSP Association Group TLV . . . . . . . 5
4. Bidirectional Flag . . . . . . . . . . . . . . . . . . . . . 6 4. PCEP Procedures . . . . . . . . . . . . . . . . . . . . . . . 5
5. Procedures for Associated Bidirectional SR Path Computation . 6 4.1. PCE Initiated Associated Bidirectional SR Paths . . . . . 6
5.1. PCE Initiated Associated Bidirectional SR Paths . . . . . 7 4.2. PCC Initiated Associated Bidirectional SR Paths . . . . . 7
5.2. PCC Initiated Associated Bidirectional SR Paths . . . . . 7 4.3. Stateless PCE . . . . . . . . . . . . . . . . . . . . . . 9
5.3. Error Handling . . . . . . . . . . . . . . . . . . . . . 9 4.4. Bidirectional (B) Flag . . . . . . . . . . . . . . . . . 9
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 10 4.5. State Synchronization . . . . . . . . . . . . . . . . . . 9
6.1. Huawei's Commercial Delivery . . . . . . . . . . . . . . 10 4.6. Error Handling . . . . . . . . . . . . . . . . . . . . . 9
6.2. ZTE's Commercial Delivery . . . . . . . . . . . . . . . . 10 5. Implementation Status . . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 5.1. Huawei's Commercial Delivery . . . . . . . . . . . . . . 10
7.1. Association Type . . . . . . . . . . . . . . . . . . . . 11 5.2. ZTE's Commercial Delivery . . . . . . . . . . . . . . . . 10
7.2. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11 7. Manageability Considerations . . . . . . . . . . . . . . . . 11
9. Manageability Considerations . . . . . . . . . . . . . . . . 12 7.1. Control of Function and Policy . . . . . . . . . . . . . 11
9.1. Control of Function and Policy . . . . . . . . . . . . . 12 7.2. Information and Data Models . . . . . . . . . . . . . . . 11
9.2. Information and Data Models . . . . . . . . . . . . . . . 12 7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 11
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 12 7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 11
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 12 7.5. Requirements On Other Protocols . . . . . . . . . . . . . 12
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 12 7.6. Impact On Network Operations . . . . . . . . . . . . . . 12
9.6. Impact On Network Operations . . . . . . . . . . . . . . 12 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13 8.1. Association Type . . . . . . . . . . . . . . . . . . . . 12
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 8.2. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 12
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
12.1. Normative References . . . . . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . 12
12.2. Informative References . . . . . . . . . . . . . . . . . 15 9.2. Informative References . . . . . . . . . . . . . . . . . 13
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 15
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
Segment routing (SR) [RFC8402] leverages the source routing and Segment routing (SR) [RFC8402] leverages the source routing and
tunneling paradigms. SR supports to steer packets into an explicit tunneling paradigms. SR supports steering packets onto an explicit
forwarding path at the ingress node. 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 [RFC5440] describes the Path Computation Element (PCE) Communication
Protocol (PCEP). PCEP enables the communication between a Path Protocol (PCEP). PCEP enables the communication between a Path
Computation Client (PCC) and a PCE, or between PCE and PCE, for the Computation Client (PCC) and a PCE, or between PCE and PCE, for the
purpose of computation of Multiprotocol Label Switching (MPLS) as purpose of computation of Traffic Engineering (TE) Label Switched
well as Generalized MPLS (GMPLS) Traffic Engineering Label Switched Paths (LSP). [RFC8231] specifies a set of extensions to PCEP to
Path (TE LSP) characteristics. enable stateful control of TE LSPs within and across PCEP sessions.
The mode of operation where LSPs are initiated from the PCE is
[RFC8231] specifies a set of extensions to PCEP to enable stateful described in [RFC8281].
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 [RFC8408] specifies extensions to the Path Computation Element
create a grouping of LSPs which can then be used to define Protocol (PCEP) [RFC5440] for SR networks, that allow a stateful PCE
associations between a set of LSPs and/or a set of attributes, for to compute and initiate SR TE paths, as well as a PCC to request,
example primary and secondary LSP associations, and is equally report or delegate them.
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, [RFC8697] introduces a generic mechanism to create a grouping of LSPs
bidirectional SR Paths are required in some networks, for example, in which can then be used to define associations between a set of LSPs
mobile backhaul transport networks. The requirement of bidirectional and/or a set of attributes, and is equally applicable to the active
SR Path is specified in [I-D.ietf-spring-mpls-path-segment]. and passive modes of a Stateful PCE [RFC8231] or a stateless PCE
[RFC5440].
[I-D.ietf-pce-association-bidir] defines PCEP extensions for grouping [I-D.ietf-pce-association-bidir] defines PCEP extensions for grouping
two reverse unidirectional MPLS TE LSPs into an Associated two unidirectional RSVP-TE LSPs into an Associated Bidirectional LSP
Bidirectional LSP when using a Stateful PCE for both PCE-Initiated when using a Stateful PCE for both PCE-Initiated and PCC-Initiated
and PCC-Initiated LSPs as well as when using a Stateless PCE. LSPs as well as when using a Stateless PCE. It specifies the
procedure for Double-sided Bidirectional LSP Association, where the
This document extends the bidirectional association to segment PCE creates the association and provisions the forward LSPs at their
routing by specifying PCEP extensions for grouping two reverse ingress nodes. The RSVP-TE signals the forward LSPs to the egress
unidirectional SR Paths into a bidirectional SR Path. nodes. Thus, both endpoints learn the reverse LSPs forming the
bidirectional LSP association.
[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 This document extends the bidirectional LSP association to SR by
Identifier (PSID) in PCEP for SR using PATH-SEGMENT TLV. The PSID specifying PCEP extensions for grouping two unidirectional SR Paths
can be a Path Segment Identifier in SR-MPLS into a bidirectional SR Path. For bidirectional SR, there are use
[I-D.ietf-spring-mpls-path-segment]. The PSID can be used for an cases such as directed BFD [I-D.ietf-mpls-bfd-directed] and SR
associated bidirectional SR Path for identifying the SR Path. performance measurement [I-D.gandhi-spring-twamp-srpm] those 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 SR Paths in both directions,
including their status and all other path related information.
2. Terminology 2. Terminology
This document makes use of the terms defined in This document makes use of the terms defined in [RFC8408]. The
[I-D.ietf-pce-segment-routing]. The reader is assumed to be familiar reader is assumed to be familiar with the terminology defined in
with the terminology defined in [RFC5440], [RFC8231], [RFC8281], [RFC5440], [RFC8231], [RFC8281], [RFC8697], and
[I-D.ietf-pce-association-group] and
[I-D.ietf-pce-association-bidir]. [I-D.ietf-pce-association-bidir].
2.1. Requirements Language 2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. PCEP Extension for Bidirectional SR Path 3. PCEP Extensions
As per [I-D.ietf-pce-association-group], LSPs are associated by As per [RFC8697], TE LSPs are associated by adding them to a common
adding them to a common association group. association group by a PCEP peer. [I-D.ietf-pce-association-bidir]
[I-D.ietf-pce-association-bidir] specifies PCEP extensions for uses the the association group object and the procedures as specified
grouping two reverse unidirectional MPLS-TE LSPs into an Associated in [RFC8697] to group two unidirectional RSVP-TE LSPs. Similarly,
Bidirectional LSP for both single-sided and double-sided initiation two SR Paths can also be associated using similar technique. This
cases by defining two new Bidirectional LSP Association Groups. 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 Bidirectional SR
Path Association Group defined in this document for PCEP messages.
This document extends the procedure for associated bidirectional SR Note that the association group defined in this document is specific
Paths by defining a new bidirectional association group (Double-sided to the bidirectional SR Paths. The procedure for this association
Bidirectional SR Path Association Group). The document further group is different than the RSVP-TE bidirectional association groups
describes the mechanism for associating two unidirectional SR Paths defined in [I-D.ietf-pce-association-bidir].
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-
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 [I-D.ietf-pce-sr-path-segment] defines a mechanism for communicating
procedures specific to SR Paths (and the procedures are different Path Segment Identifier (PSID) in PCEP for SR. The PSID is defined
than the RSVP-TE bidirectional association groups defined in for SR-MPLS in [I-D.ietf-spring-mpls-path-segment]. The PSID can be
[I-D.ietf-pce-association-bidir]). 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 SR Path Association Group Object 3.1. Double-sided Bidirectional SR Path Association Group
As defined in [I-D.ietf-pce-association-bidir], two LSPs are For associating two unidirectional SR paths, this document defines a
associated as a bidirectional MPLS-TE LSP by a common bidirectional new Association Type called 'Double-sided Bidirectional SR Path
LSP association group. For associating two SR paths, this document Association Group' for Association Group Object (Class-Value 40) as
defines a new association group called 'Double-sided Bidirectional SR follows:
Path Association Group' as follows:
o Association Type (TBD1 to be assigned by IANA) = Double-sided o Association Type (TBD1 to be assigned by IANA) = Double-sided
Bidirectional SR Path Association Group Bidirectional SR Path Association Group
Similar to other bidirectional associations, this Association Type is Similar to RSVP-TE bidirectional LSP associations, this Association
operator-configured in nature and statically created by the operator Type is operator-configured in nature and statically created by the
on the PCEP peers. The paths belonging to this association is operator on the PCEP peers. The paths belonging to this association
conveyed via PCEP messages to the PCEP peer. Operator-configured is conveyed via PCEP messages to the PCEP peer. Operator-configured
Association Range TLV [I-D.ietf-pce-association-group] MUST NOT be Association Range TLV [RFC8697] MUST NOT be sent for these
sent for these Association Types, and MUST be ignored, so that the Association Types, and MUST be ignored, so that the entire range of
entire range of association ID can be used for them. The handling of association ID can be used for them. The handling of the Association
the Association ID, Association Source, optional Global Association ID, Association Source, optional Global Association Source and
Source and optional Extended Association ID in this association are optional Extended Association ID in this association are set in the
set in the same way as [I-D.ietf-pce-association-bidir]. same way as [I-D.ietf-pce-association-bidir].
A member of the 'Double-sided Bidirectional SR Path Association A member of the 'Double-sided Bidirectional SR Path Association
Group' can take the role of a forward or reverse SR Path and follow 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 the similar rules defined in [I-D.ietf-pce-association-bidir] for
LSPs. LSPs.
o An SR Path (forward or reverse) can not be part of more than one o An SR Path (forward or reverse) cannot be part of more than one
'Double-sided Bidirectional SR Path Association Group'. 'Double-sided Bidirectional SR Path Association Group'.
o The endpoints of the SR Paths in this associations cannot be o The endpoints of the SR Paths in this associations cannot be
different. different.
For describing the SR Paths in this association group, such as 3.1.1. Bidirectional LSP Association Group TLV
direction and co-routed information, this association group reuses
the Bidirectional LSP Association Group TLV defined in In Bidirectional SR 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 [I-D.ietf-pce-association-bidir]. All fields and processing rules
are as per [I-D.ietf-pce-association-bidir]. are as per [I-D.ietf-pce-association-bidir].
4. Bidirectional Flag 4. PCEP Procedures
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 For bidirectional SR path, an ingress PCC is aware of the forward
direction SR paths. The PCE SHOULD inform the reverse SR Paths to direction SR path beginning from itself to the egress PCC using the
the ingress PCCs and vice versa. To achieve this, a PCInitiate existing PCEP procedures. For the use-cases which require the
message for the reverse SR Path is sent to the ingress PCC and a ingress PCC to be aware of the reverse direction SR path, PCE informs
PCInitiate message for the forward SR Path is sent to the egress PCC the reverse SR Path to the ingress PCC. To achieve this, a
(with the same association group). These PCInitiate message MUST NOT PCInitiate message for the reverse SR Path is sent to the ingress PCC
trigger initiation of SR Paths. The reverse direction SR Path can be and a PCInitiate message for the forward SR Path is sent to the
used for several use-cases, such as directed BFD egress PCC (with the matching association group). These PCInitiate
[I-D.ietf-mpls-bfd-directed]. message MUST NOT trigger initiation of SR Paths on PCCs.
For a bidirectional LSP computation when using both direction LSPs on For a bidirectional LSP computation when using both direction LSPs on
a node, the same LSP would need to be identified using 2 different 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 PLSP-IDs based on the PCEP session to the ingress or the egress node.
other words, the LSP will have a PLSP-ID A at the ingress node while Note that the PLSP-ID space is independent at each PCC, the PLSP-ID
it will have the PLSP-ID B at the egress node. The PCE will maintain allocated by the egress PCC cannot be used for the LSP at the ingress
the two PLSP-IDs for the same LSP. For instance, an ingress PCC PCC (PLSP-ID conflict may occur). As per normal PCInitiate
requests a bidirectional SR Path computation, and the PCE computes a operations, PCC assigns the PLSP-IDs for the local LSPs. Hence, when
forward LSP1 with PLSP-ID say 100. The reverse LSP2 from the egress the PCE notifies an ingress PCC of the reverse LSP, it does so by
to the ingress with PLSP-ID say 200 is allocated by the egress PCC. using PCInitiate operations and sets PLSP-ID to zero and sets the R
Since the PLSP-ID space is independent at each PCC, the PLSP-ID bit in the Bidirectional LSP Association Group TLV in the association
allocated by the egress PCC can not be used for the LSP at the object to indicate that this PCInitiate LSP is a reverse LSP. The
ingress PCC (PLSP-ID conflict may occur). Hence, the PCE needs to PCC upon receiving the PCInitiate MUST locally assign a new PLSP-ID
allocate a PLSP-ID for LSP2 from the ingress PCC's PLSP-ID space , and it MUST issue a PCRpt to PCE for this LSP containing the new
say 101. Similarly for LSP1, it has PLSP-ID 100 at the ingress, and PLSP-ID. This reverse direction LSP MUST NOT be instantiated on the
may have say PLSP-ID 201 at the egress node. PCC.
5.1. PCE Initiated Associated Bidirectional SR Paths 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).
As specified in [I-D.ietf-pce-association-group], Bidirectional SR 4.1. PCE Initiated Associated Bidirectional SR Paths
Path Association Group can be created by a Stateful PCE.
As specified in [RFC8697], Bidirectional SR Path Association Group
can be created by a Stateful PCE as shown in Figure 1.
o Stateful PCE can create and update the forward and reverse SR o Stateful PCE can create and update the forward and reverse SR
Paths independently for a 'Double-sided Bidirectional SR Path Paths independently for 'Double-sided Bidirectional SR Path
Association Group'. Association Group'.
o Stateful PCE can establish and remove the association relationship o Stateful PCE can establish and remove the association relationship
on a per SR Path basis. on a per SR Path basis.
o Stateful PCE can create and update the SR Path and the association o Stateful PCE can create and update the SR Path and the association
on a PCC via PCInitiate and PCUpd messages, respectively, using on a PCC via PCInitiate and PCUpd messages, respectively, using
the procedures described in [I-D.ietf-pce-association-group]. the procedures described in [RFC8697].
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 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 D as shown in Figure 1) SHOULD be informed by the PCE via
matching association group. 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 | | PCE |
+-----+ +-----+
PCInitiate/PCUpd: / \ PCInitiate/PCUpd: PCInitiate/PCUpd: / \ PCInitiate/PCUpd:
Tunnel 1 (F) / \ Tunnel 2 (F) Tunnel 1 (F) / \ Tunnel 2 (F)
(LSP1 (F), LSP2 (R)) / \ (LSP2 (F), LSP1 (R)) (LSP1 (F), LSP2 (R)) / \ (LSP2 (F), LSP1 (R))
Association #1 / \ Association #1 Association #1 / \ Association #1
/ \ / \
v v v v
+-----+ LSP1 +-----+ +-----+ LSP1 +-----+
| S |------------>| D | | S |------------>| D |
| |<------------| | | |<------------| |
+-----+ LSP2 +-----+ +-----+ LSP2 +-----+
<no signaling> <no signaling>
Figure 1: PCE-Initiated Double-sided Bidirectional SR Path Figure 1: PCE-Initiated Double-sided Bidirectional SR Path
with Forward and Reverse Direction SR Paths with Forward and Reverse Direction SR Paths
5.2. PCC Initiated Associated Bidirectional SR Paths 4.2. PCC Initiated Associated Bidirectional SR Paths
As specified in [I-D.ietf-pce-association-group], Bidirectional SR As specified in [RFC8697], Bidirectional SR Path Association Group
Path Association Group can also be created by a PCC. can also be created by a PCC as shown in Figure 2a and 2b.
o PCC can create and update the forward and reverse SR Paths o PCC can create and update the forward SR Path and update the
independently for a 'Double-sided Bidirectional SR Path reverse SR Path independently for a 'Double-sided Bidirectional SR
Association Group'. Path Association Group'.
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 o PCC can establish and remove the association relationship on a per
SR Path basis. SR Path basis.
o PCC MUST report the change in the association group of an SR Path o PCC MUST report the change in the association group of an SR Path
to PCE(s) via PCRpt message. to PCE(s) via PCRpt message.
o PCC can report the forward and reverse SR Paths independently to o PCC can report the forward and reverse SR Paths independently to
PCE(s) via PCRpt message. PCE(s) via PCRpt message.
o PCC can delegate the forward and reverse SR Paths independently to o PCC can delegate the forward and reverse SR Paths independently to
a Stateful PCE, where PCE would control the SR Paths. a Stateful PCE, where PCE would control the SR Paths.
o Stateful PCE can update the SR Paths in the 'Double-sided o Stateful PCE can update the SR Paths in the 'Double-sided
Bidirectional SR Path Association Group' via PCUpd message, using Bidirectional SR Path Association Group' via PCUpd message, using
the procedures described in [I-D.ietf-pce-association-group]. the procedures described in [RFC8697].
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 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 D as shown in Figure 2b) SHOULD be informed by the PCE via
matching association group. 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 | | PCE |
+-----+ +-----+
Report/Delegate: ^ ^ Report/Delegate: Report/Delegate: ^ ^ Report/Delegate:
Tunnel 1 (F) / \ Tunnel 2 (F) Tunnel 1 (F) / \ Tunnel 2 (F)
(LSP1 (F)) / \ (LSP2 (F)) (LSP1 (F)) / \ (LSP2 (F))
Association #2 / \ Association #2 Association #2 / \ Association #2
/ \ / \
/ \ / \
+-----+ LSP1 +-----+ +-----+ LSP1 +-----+
| S |------------>| D | | S |------------>| D |
| |<------------| | | |<------------| |
+-----+ LSP2 +-----+ +-----+ LSP2 +-----+
<no signaling> <no signaling>
Figure 2a: Step 1: PCC-Initiated Double-sided Bidirectional SR Path Figure 2a: Step 1: PCC-Initiated Double-sided Bidirectional
with Forward Direction SR Paths SR Path with Forward Direction SR Paths
+-----+ +-----+
| PCE | | PCE |
+-----+ +-----+
PCUpd/PCInitiate: / \ PCUpd/PCInitiate: PCUpd/PCInitiate: / \ PCUpd/PCInitiate:
Tunnel 1 (F) / \ Tunnel 2 (F) Tunnel 1 (F) / \ Tunnel 2 (F)
(LSP1 (F), LSP2 (R)) / \ (LSP2 (F), LSP1 (R)) (LSP1 (F), LSP2 (R)) / \ (LSP2 (F), LSP1 (R))
Association #2 / \ Association #2 Association #2 / \ Association #2
/ \ / \
v v v v
+-----+ LSP1 +-----+ +-----+ LSP1 +-----+
| S |------------>| D | | S |------------>| D |
| |<------------| | | |<------------| |
+-----+ LSP2 +-----+ +-----+ LSP2 +-----+
<no signaling> <no signaling>
Figure 2b: Step 2: PCE-Upd/Initiated Double-sided Bidirectional Path Figure 2b: Step 2: PCE-Updated/Initiated Double-sided Bidirectional
Along with Reverse Direction SR Paths SR Path with Reverse Direction SR Paths
5.3. Error Handling 4.3. Stateless PCE
The error handling as described in section 5.5 of 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
As defined in [RFC5440], the Bidirectional (B) flag in Request
Parameters (RP) object MUST be set when the PCC specifies that the
path computation request relates to a bidirectional TE LSP. The
B-flag also MUST be set when the PCC specifies that the path
computation request relates to an associated bidirectional SR Path.
Note that the B-flag defined in Stateful PCE Request Parameter (SRP)
object [I-D.ietf-pce-pcep-stateful-pce-gmpls] is not required for
associated bidirectional SR path as association group is used to
indicate that the path is bidirectional.
4.5. State Synchronization
During state synchronization, a PCC MUST report all the existing
Bidirectional SR Association Groups to the Stateful PCE as per
[RFC8697]. After the state synchronization, the PCE MUST remove all
stale Bidirectional SR Associations.
4.6. Error Handling
The error handling as described in section 5.7 of
[I-D.ietf-pce-association-bidir] continue to apply. [I-D.ietf-pce-association-bidir] continue to apply.
The PCEP Path Setup Type (PST) MUST be set to 'TE Path is Setup using The PCEP Path Setup Type (PST) for SR is set to 'TE Path is Setup
Segment Routing' [I-D.ietf-pce-segment-routing] for the LSP belonging using Segment Routing' [RFC8408]. If a PCEP speaker receives a
to the 'Double-sided Bidirectional SR Path Association Group'. In different PST value for Bidirectional SR Path association group and
case a PCEP speaker receives a different PST value for this it does not support; it MUST send a PCErr message with Error-Type =
association group, it MUST send a PCErr message with Error-Type = 29 26 (Association Error) and Error-Value = TBD2 (Bidirectional LSP
(Early allocation by IANA) (Association Error) and Error-Value = TBD2 Association - Path Setup Type Not Supported).
(Bidirectional LSP Association - Path Setup Type Mismatch).
6. Implementation Status 5. Implementation Status
[Note to the RFC Editor - remove this section before publication, as [Note to the RFC Editor - remove this section before publication, as
well as remove the reference to [RFC7942]. well as remove the reference to [RFC7942].
This section records the status of known implementations of the This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942]. Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation RFCs. Please note that the listing of any individual implementation
skipping to change at page 10, line 32 skipping to change at page 10, line 22
features. Readers are advised to note that other implementations may features. Readers are advised to note that other implementations may
exist. exist.
According to [RFC7942], "this will allow reviewers and working groups According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature. and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as It is up to the individual working groups to use this information as
they see fit". they see fit".
6.1. Huawei's Commercial Delivery 5.1. Huawei's Commercial Delivery
The feature is developing based on Huawei VRP8. The feature is developing based on Huawei VRP8.
o Organization: Huawei o Organization: Huawei
o Implementation: Huawei's Commercial Delivery implementation based o Implementation: Huawei's Commercial Delivery implementation based
on VRP8. on VRP8.
o Description: The implementation is under development. o Description: The implementation is under development.
o Maturity Level: Product o Maturity Level: Product
o Contact: tanren@huawei.com o Contact: tanren@huawei.com
6.2. ZTE's Commercial Delivery 5.2. ZTE's Commercial Delivery
o Organization: ZTE o Organization: ZTE
o Implementation: ZTE's Commercial Delivery implementation based on o Implementation: ZTE's Commercial Delivery implementation based on
Rosng v8. Rosng v8.
o Description: The implementation is under development. o Description: The implementation is under development.
o Maturity Level: Product o Maturity Level: Product
o Contact: zhan.shuangping@zte.com.cn o Contact: zhan.shuangping@zte.com.cn
7. IANA Considerations 6. Security 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], The security considerations described in [RFC5440], [RFC8231],
[RFC8281], and [I-D.ietf-pce-segment-routing] apply to the extensions [RFC8281], and [RFC8408] apply to the extensions defined in this
defined in this document as well. document as well.
A new Association Type for the Association Object, 'Double-sided A new Association Type for the Association Object, 'Double-sided
Associated Bidirectional SR Path Association Group' is introduced in Associated Bidirectional SR Path Association Group' is introduced in
this document. Additional security considerations related to LSP this document. Additional security considerations related to LSP
associations due to a malicious PCEP speaker is described in associations due to a malicious PCEP speaker is described in
[I-D.ietf-pce-association-group] and apply to this Association Type. [RFC8697] and apply to this Association Type. Hence, securing the
Hence, securing the PCEP session using Transport Layer Security (TLS) PCEP session using Transport Layer Security (TLS) [RFC8253] is
[RFC8253] is recommended. recommended.
9. Manageability Considerations 7. Manageability Considerations
All manageability requirements and considerations listed in All manageability requirements and considerations listed in
[RFC5440], [RFC8231], and [RFC8281] apply to PCEP protocol extensions [RFC5440], [RFC8231], and [RFC8281] apply to PCEP protocol extensions
defined in this document. In addition, requirements and defined in this document. In addition, requirements and
considerations listed in this section apply. considerations listed in this section apply.
9.1. Control of Function and Policy 7.1. Control of Function and Policy
The mechanisms defined in this document do not imply any control or The mechanisms defined in this document do not imply any control or
policy requirements in addition to those already listed in [RFC5440], policy requirements in addition to those already listed in [RFC5440],
[RFC8231], and [RFC8281]. [RFC8231], and [RFC8281].
9.2. Information and Data Models 7.2. Information and Data Models
[RFC7420] describes the PCEP MIB, there are no new MIB Objects [RFC7420] describes the PCEP MIB, there are no new MIB Objects
defined for Bidirectional SR Path associations. The PCEP YANG module defined for Bidirectional SR Path associations. The PCEP YANG module
[I-D.ietf-pce-pcep-yang] defines data model for Bidirectional SR Path [I-D.ietf-pce-pcep-yang] defines data model for Bidirectional SR Path
associations. associations.
9.3. Liveness Detection and Monitoring 7.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already detection and monitoring requirements in addition to those already
listed in [RFC5440], [RFC8231], and [RFC8281]. listed in [RFC5440], [RFC8231], and [RFC8281].
9.4. Verify Correct Operations 7.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in verification requirements in addition to those already listed in
[RFC5440], [RFC8231], and [I-D.ietf-pce-segment-routing] . [RFC5440], [RFC8231], and [RFC8408].
9.5. Requirements On Other Protocols 7.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements Mechanisms defined in this document do not imply any new requirements
on other protocols. on other protocols.
9.6. Impact On Network Operations 7.6. 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.
10. Contributors
The following people have substantially contributed to this document: Mechanisms defined in [RFC5440], [RFC8231], and [RFC8408] also apply
to PCEP extensions defined in this document.
Dhruv Dhody 8. IANA Considerations
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com 8.1. Association Type
Zhenbin Li This document defines a new Association Type for the Association
Huawei Technologies Object (Class Value 40) defined [RFC8697]. IANA is requested to make
Huawei Campus, No. 156 Beiqing Rd. the assignment of a type for the sub-registry "ASSOCIATION Type" as
Beijing 100095 follows:
China
Email: lizhenbin@huawei.com Type Name Reference
-------------------------------------------------------------------
TBD1 Double-sided Bidirectional SR Path This document
Association Group
Jie Dong 8.2. PCEP Errors
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: jie.dong@huawei.com This document defines new Error value for Error Type 26 (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:
11. Acknowledgments Error Type Description Reference
-------------------------------------------------------------------
26 Association Error
Many thanks to Marina Fizgeer for detailed review and comments. Error value: TBD2 This document
Bidirectional LSP Association -
Path Setup Type Not Supported
12. References 9. References
12.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440, Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009, DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>. <https://www.rfc-editor.org/info/rfc5440>.
skipping to change at page 14, line 21 skipping to change at page 13, line 26
Extensions for Stateful PCE", RFC 8231, Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017, DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>. <https://www.rfc-editor.org/info/rfc8231>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP) Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>. <https://www.rfc-editor.org/info/rfc8281>.
[I-D.ietf-pce-association-group] [RFC8697] Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Dhody, D., and Y. Tanaka, "Path Computation Element Dhody, D., and Y. Tanaka, "Path Computation Element
Communication Protocol (PCEP) Extensions for Establishing Communication Protocol (PCEP) Extensions for Establishing
Relationships Between Sets of Label Switched Paths Relationships between Sets of Label Switched Paths
(LSPs)", draft-ietf-pce-association-group-10 (work in (LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020,
progress), August 2019. <https://www.rfc-editor.org/info/rfc8697>.
[I-D.ietf-pce-association-bidir] [I-D.ietf-pce-association-bidir]
Gandhi, R., Barth, C., and B. Wen, "PCEP Extensions for Gandhi, R., Barth, C., and B. Wen, "PCEP Extensions for
Associated Bidirectional Label Switched Paths (LSPs)", Associated Bidirectional Label Switched Paths (LSPs)",
draft-ietf-pce-association-bidir-05 (work in progress), draft-ietf-pce-association-bidir-05 (work in progress),
February 2020. February 2020.
[I-D.ietf-pce-pcep-stateful-pce-gmpls] [I-D.ietf-pce-sr-path-segment]
Lee, Y., Zheng, H., Dios, O., Lopezalvarez, V., and Z. Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong,
Ali, "Path Computation Element (PCE) Protocol Extensions "Path Computation Element Communication Protocol (PCEP)
for Stateful PCE Usage in GMPLS-controlled Networks", Extension for Path Segment in Segment Routing (SR)",
draft-ietf-pce-pcep-stateful-pce-gmpls-12 (work in draft-ietf-pce-sr-path-segment-00 (work in progress),
progress), October 2019. 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.
12.2. Informative References
[RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation 9.2. Informative References
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, [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the "PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)", Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017, RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>. <https://www.rfc-editor.org/info/rfc8253>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
skipping to change at page 15, line 34 skipping to change at page 14, line 21
Code: The Implementation Status Section", BCP 205, Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016, RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>. <https://www.rfc-editor.org/info/rfc7942>.
[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Communication Protocol Hardwick, "Path Computation Element Communication Protocol
(PCEP) Management Information Base (MIB) Module", (PCEP) Management Information Base (MIB) Module",
RFC 7420, DOI 10.17487/RFC7420, December 2014, RFC 7420, DOI 10.17487/RFC7420, December 2014,
<https://www.rfc-editor.org/info/rfc7420>. <https://www.rfc-editor.org/info/rfc7420>.
[I-D.ietf-pce-segment-routing] [RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J.
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., Hardwick, "Conveying Path Setup Type in PCE Communication
and J. Hardwick, "PCEP Extensions for Segment Routing", Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408,
draft-ietf-pce-segment-routing-16 (work in progress), July 2018, <https://www.rfc-editor.org/info/rfc8408>.
March 2019.
[I-D.ietf-mpls-bfd-directed] [I-D.ietf-mpls-bfd-directed]
Mirsky, G., Tantsura, J., Varlashkin, I., and M. Chen, Mirsky, G., Tantsura, J., Varlashkin, I., and M. Chen,
"Bidirectional Forwarding Detection (BFD) Directed Return "Bidirectional Forwarding Detection (BFD) Directed Return
Path", draft-ietf-mpls-bfd-directed-13 (work in progress), Path", draft-ietf-mpls-bfd-directed-13 (work in progress),
December 2019. December 2019.
[I-D.gandhi-spring-twamp-srpm]
Gandhi, R., Filsfils, C., Voyer, D., Chen, M., and B.
Janssens, "Performance Measurement Using TWAMP Light for
Segment Routing Networks", draft-gandhi-spring-twamp-
srpm-05 (work in progress), December 2019.
[I-D.ietf-spring-mpls-path-segment] [I-D.ietf-spring-mpls-path-segment]
Cheng, W., Li, H., Chen, M., Gandhi, R., and R. Zigler, Cheng, W., Li, H., Chen, M., Gandhi, R., and R. Zigler,
"Path Segment in MPLS Based Segment Routing Network", "Path Segment in MPLS Based Segment Routing Network",
draft-ietf-spring-mpls-path-segment-01 (work in progress), draft-ietf-spring-mpls-path-segment-01 (work in progress),
September 2019. September 2019.
[I-D.ietf-pce-pcep-yang] [I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep- Communications Protocol (PCEP)", draft-ietf-pce-pcep-
yang-13 (work in progress), October 2019. yang-13 (work in progress), October 2019.
[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.
Acknowledgments
Many thanks to Marina Fizgeer, Adrian Farrel, and Andrew Stone for
the detailed review of this document and providing many useful
comments.
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
Authors' Addresses Authors' Addresses
Cheng Li Cheng Li
Huawei Technologies Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd. Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095 Beijing 100095
China China
Email: chengli13@huawei.com Email: chengli13@huawei.com
 End of changes. 77 change blocks. 
349 lines changed or deleted 364 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/