Path Computation Element Communication Protocol (PCEP) Extensions for Associated Bidirectional Segment Routing (SR) Paths
draft-ietf-pce-sr-bidir-path-12
| Document | Type | Active Internet-Draft (pce WG) | |
|---|---|---|---|
| Authors | Cheng Li , Mach Chen , Weiqiang Cheng , Rakesh Gandhi , Quan Xiong | ||
| Last updated | 2023-09-09 | ||
| Replaces | draft-li-pce-sr-bidir-path | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-pce-sr-bidir-path-12
PCE Working Group C. Li
Internet-Draft M. Chen
Intended status: Standards Track Huawei Technologies
Expires: 12 March 2024 W. Cheng
China Mobile
R. Gandhi
Cisco Systems, Inc.
Q. Xiong
ZTE Corporation
9 September 2023
Path Computation Element Communication Protocol (PCEP) Extensions for
Associated Bidirectional Segment Routing (SR) Paths
draft-ietf-pce-sr-bidir-path-12
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 or 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."
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This Internet-Draft will expire on 12 March 2024.
Copyright Notice
Copyright (c) 2023 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/
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Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Bidirectional SR Policy Association . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Double-Sided Bidirectional with Reverse LSP
Association . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.1. Bidirectional LSP Association Group TLV . . . . . . . 6
4. PCEP Procedures . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. PCE-Initiated Associated Bidirectional SR Paths . . . . . 7
4.2. PCC-Initiated Associated Bidirectional SR Paths . . . . . 8
4.3. Stateless PCE . . . . . . . . . . . . . . . . . . . . . . 11
4.4. Bidirectional (B) Flag . . . . . . . . . . . . . . . . . 11
4.5. PLSP-ID Usage . . . . . . . . . . . . . . . . . . . . . . 11
4.6. State Synchronization . . . . . . . . . . . . . . . . . . 12
4.7. Error Handling . . . . . . . . . . . . . . . . . . . . . 12
5. Implementation Status . . . . . . . . . . . . . . . . . . . . 12
5.1. Huawei's Commercial Delivery . . . . . . . . . . . . . . 13
5.2. ZTE's Commercial Delivery . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7. Manageability Considerations . . . . . . . . . . . . . . . . 14
7.1. Control of Function and Policy . . . . . . . . . . . . . 14
7.2. Information and Data Models . . . . . . . . . . . . . . . 14
7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 14
7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 14
7.5. Requirements On Other Protocols . . . . . . . . . . . . . 14
7.6. Impact On Network Operations . . . . . . . . . . . . . . 15
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
8.1. Association Type . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
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9.1. Normative References . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . 16
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 18
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
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] and
[I-D.ietf-spring-srv6-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. This grouping can then be used to define associations between
sets of LSPs or between a set of LSPs and a set of attributes, and it
is equally applicable to the stateful PCE (active and passive modes)
[RFC8231] and the stateless PCE [RFC5440].
For bidirectional SR paths, there are use-cases such as directed BFD
[I-D.ietf-mpls-bfd-directed] and Performance Measurement (PM)
[I-D.ietf-spring-stamp-srpm] those require ingress node (PCC) to be
aware of the reverse direction SR Path. For such use-cases, the
reverse SR Paths need to be communicated to the ingress node (PCCs)
using PCEP mechanisms. This allows both endpoint ingress nodes to be
aware of the SR Paths in both directions, including their status and
all other path related information.
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[RFC9059] defines PCEP extensions for grouping two unidirectional
Resource Reservation Protocol - Traffic Engineering (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. Specifically, it defines 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 paths
by specifying PCEP extensions for grouping two unidirectional SR
Paths into an associated bidirectional SR Path. Note that the
procedure for using the association group defined in this document is
specific to the associated bidirectional SR Paths. 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.
1.1. Bidirectional SR Policy Association
An SR Policy contains one or more SR Policy Candidate Paths (CPs)
[RFC9256] where one or more such Candidate Paths can be computed via
PCE. Each Candidate Path maps to a unique PLSP-ID in PCEP. Multiple
Candidate Paths can be associated together into a single SR Policy,
via the use of the PCEP Association object with the "SR Policy
Association" type as specified in [RFC9256]. The two such
unidirectional Candidate Paths can be associated to form a
bidirectional Candidate Path using the procedure defined in this
document.
Each Candidate Path of an SR Policy can contain one or more Segment
Lists (SLs) [RFC9256]. When a Candidate Path is computed by the PCE,
it means that the PCE computed all SLs of that Candidate Path.
[I-D.ietf-pce-multipath] defines procedure for carrying multiple SLs
in a Candidate Path. That procedure works at the SL level to
identify the forward and the reverse direction SLs in a Candidate
Path as shown in an Example in Section 7.4 (Opposite Direction
Tunnels) in [I-D.ietf-pce-multipath]. Whereas the procedure defined
in this document works at the Candidate Path level to identify the
forward and the reverse direction Candidate Paths in a bidirectional
SR Policy.
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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 [RFC9059].
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. [RFC9059] uses the association
group object and the procedures as specified in [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 SR-MPLS PSID is
defined in [I-D.ietf-spring-mpls-path-segment] and SRv6 PSID is
defined in [I-D.ietf-spring-srv6-path-segment]. The PSID can be used
for identifying the SR Path of an associated bidirectional SR Path.
The PATH-SEGMENT TLV MAY be included for the SR Path in the LSP
object to support the use-cases as required. 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
For associating two unidirectional SR Paths, this document defines a
new Association Type called 'Double-Sided Bidirectional with Reverse
LSP Association' for Association Group object (Class-Value 40) as
follows:
* Association Type (TBD1 to be assigned by IANA) = Double-Sided
Bidirectional with Reverse LSP Association
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The bidirectional association is considered to be both dynamic and
operator-configured in nature. As per [RFC8697], the association
group could be manually created by the operator on the PCEP peers,
and the LSPs belonging to this association are conveyed via PCEP
messages to the PCEP peer; alternately, the association group could
be created dynamically by the PCEP speaker, and both the association
group information and the LSPs belonging to the association group are
conveyed to the PCEP peer. The Operator-configured Association Range
MUST be set for this Association Type to mark a range of Association
Identifiers that are used for operator-configured associations to
avoid any Association Identifier clash within the scope of the
Association Source (Refer to [RFC8697]). Specifically, for the PCE-
initiated associated bidirectional SR Paths, the Association Type is
dynamically created by the PCE on the PCE peers.
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 [RFC9059].
[RFC8697] specifies the mechanism for the capability advertisement of
the Association Types supported by a PCEP speaker by defining an
ASSOC-Type-List TLV (value 35) to be carried within an OPEN object.
This capability exchange for the Bidirectional Association MUST be
done before using the Bidirectional Association Type. Thus, the PCEP
speaker MUST include the bidirectional Association Type in the ASSOC-
Type-List TLV and MUST receive the same from the PCEP peer before
using the Bidirectional Association in PCEP messages.
A member of the 'Double-Sided Bidirectional with Reverse LSP
Association' can take the role of a forward or reverse direction SR
Path and follow the similar rules defined in [RFC9059] for LSPs.
* An SR Path (forward or reverse) MUST NOT be part of more than one
'Double-Sided Bidirectional with Reverse LSP Association'.
* The endpoint nodes of the SR Paths in 'Double-Sided Bidirectional
with Reverse LSP Association' MUST be matching in the reverse
directions.
3.1.1. Bidirectional LSP Association Group TLV
In 'Double-Sided Bidirectional with Reverse LSP Association', for
properties such as forward and reverse direction and co-routed path,
it uses the 'Bidirectional LSP Association Group TLV' defined in
[RFC9059]. All fields and processing rules are as per [RFC9059].
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4. PCEP Procedures
For an associated bidirectional SR Path, an ingress node PCC is aware
of the forward direction SR Path beginning from itself to the egress
node PCC using the existing PCEP procedures. For the use-cases which
require the ingress node PCC to be aware of the reverse direction SR
Path, PCE informs the reverse SR Path to the ingress node PCC. To
achieve this, a PCInitiate message for the reverse SR Path is sent to
the ingress node PCC and a PCInitiate message for the forward SR Path
is sent to the egress node PCC (with the matching association group).
These PCInitiate message MUST NOT trigger initiation of SR Paths on
PCCs.
The PCEP procedure defined in this document is applicable to the
following three scenarios:
* Neither unidirectional LSP exists, and both must be established.
* Both unidirectional LSPs exist, but the association must be
established.
* One LSP exists, but the reverse associated LSP must be
established.
4.1. PCE-Initiated Associated Bidirectional SR Paths
As specified in [RFC8697], associated bidirectional SR Paths can be
created and updated by a Stateful PCE as shown in Figure 1.
* Stateful PCE MAY create and update the forward and reverse SR
Paths independently for the 'Double-Sided Bidirectional with
Reverse LSP Association'.
* Stateful PCE MAY establish and remove the association relationship
on a per SR Path basis.
* Stateful PCE MUST create and update the SR Path and the
association on a PCC via PCInitiate and PCUpd messages,
respectively, using the procedures described in [RFC8697].
* 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>
Legends: F = Forward LSP, R = Reverse LSP, (0) = PLSP-IDs
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>
Legends: F=Forward LSP, R = Reverse LSP, (100,200,300,400)=PLSP-IDs
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 and updated by a PCC as shown in Figure 2a and 2b.
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* PCC MAY create and update the forward SR Path and update the
reverse SR Path independently for the 'Double-Sided Bidirectional
with Reverse LSP Association'.
* PCC MUST NOT instantiate a reverse SR Path in a bidirectional SR
Path.
* PCC MAY establish and remove the association relationship on a per
SR Path basis.
* PCC MUST report the change in the association group of an SR Path
to PCE(s) via PCRpt message.
* PCC reports the forward and reverse SR Paths independently to
PCE(s) via PCRpt message.
* PCC MAY delegate the forward and reverse SR Paths independently to
a Stateful PCE, where PCE would control the SR Paths.
* Stateful PCE updates the SR Paths in the 'Double-Sided
Bidirectional with Reverse LSP Association' via PCUpd message,
using the procedures described in [RFC8697].
* 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>
Legends: F = Forward LSP, R = Reverse LSP, (100,200) = PLSP-IDs
Figure 2a: Step 1: PCC-Initiated Associated Bidirectional SR
Path with Forward Direction SR Paths
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+-----+
| PCE |
+-----+
PCInitiate: / \ PCInitiate:
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>
Legends: F = Forward LSP, R = Reverse LSP, (0,100,200) = PLSP-IDs
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>
Legends: F=Forward LSP, R = Reverse LSP, (100,200,300,400)=PLSP-IDs
Figure 2c: Step 3: PCC-Reported Associated Bidirectional SR
Path with Reverse Direction SR Paths
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4.3. Stateless PCE
As defined in [RFC9059], 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 [RFC8697]. A PCC can request co-routed or
non-co-routed forward and reverse direction paths from a stateless
PCE for a bidirectional SR Path.
4.4. Bidirectional (B) Flag
The Bidirectional (B) flag in Request Parameters (RP) object
[RFC5440] and Stateful PCE Request Parameter (SRP) object
[I-D.ietf-pce-pcep-stateful-pce-gmpls] follow the procedure defined
in [RFC9059].
4.5. PLSP-ID Usage
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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For an associated bidirectional SR Path, LSP-IDENTIFIERS TLV
[RFC8231] MUST be included in all forward and reverse LSPs.
4.6. State Synchronization
During state synchronization, a PCC MUST report all the existing
Bidirectional Associations to the Stateful PCE as per [RFC8697].
After the state synchronization, the PCE MUST remove all stale
Bidirectional Associations.
4.7. Error Handling
The error handling as described in section 5.7 of [RFC9059] continue
to apply.
The PCEP Path Setup Type (PST) for SR is set to 'TE Path is Setup
using Segment Routing' [RFC8408] or 'Path is setup using SRv6'
[RFC9256].
If a PCEP speaker receives a different PST value for the 'Double-
Sided Bidirectional with Reverse LSP Association', the PCE speaker
MUST return a PCErr message with Error-Type = 26 (Association Error)
and Error-value = '16: Path Setup Type not supported' defined in
[RFC9059].
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.
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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".
5.1. Huawei's Commercial Delivery
The feature is developing based on Huawei VRP8.
* Organization: Huawei
* Implementation: Huawei's Commercial Delivery implementation based
on VRP8.
* Description: The implementation is under development.
* Maturity Level: Product
* Contact: tanren@huawei.com
5.2. ZTE's Commercial Delivery
* Organization: ZTE
* Implementation: ZTE's Commercial Delivery implementation based on
Rosng v8.
* Description: The implementation is under development.
* Maturity Level: Product
* 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.
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A new Association Type for the Association object, 'Double-Sided
Bidirectional with Reverse LSP Association' is introduced in this
document. Additional security considerations related to LSP
associations due to a malicious PCEP speaker are 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.
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
Associations'. 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.
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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, originally described in
[RFC8697]. IANA is requested to assign the following new value in
the "ASSOCIATION Type Field" subregistry [RFC8697] within the "Path
Computation Element Protocol (PCEP) Numbers" registry:
Type Name Reference
---------------------------------------------------------------------
TBD1 Double-Sided Bidirectional with Reverse [This document]
LSP Association
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>.
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[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>.
[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>.
[RFC9059] Gandhi, R., Ed., Barth, C., and B. Wen, "Path Computation
Element Communication Protocol (PCEP) Extensions for
Associated Bidirectional Label Switched Paths (LSPs)",
RFC 9059, DOI 10.17487/RFC9059, June 2021,
<https://www.rfc-editor.org/info/rfc9059>.
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>.
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[RFC9256] Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
A., and P. Mattes, "Segment Routing Policy Architecture",
RFC 9256, DOI 10.17487/RFC9256, July 2022,
<https://www.rfc-editor.org/info/rfc9256>.
[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)", Work
in Progress, Internet-Draft, draft-ietf-pce-sr-path-
segment-08, 24 August 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-pce-sr-
path-segment-08>.
[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)", Work in
Progress, Internet-Draft, draft-ietf-mpls-bfd-directed-24,
2 July 2023, <https://datatracker.ietf.org/doc/html/draft-
ietf-mpls-bfd-directed-24>.
[I-D.ietf-spring-stamp-srpm]
Gandhi, R., Filsfils, C., Voyer, D., Chen, M., and R. F.
Foote, "Performance Measurement Using Simple TWAMP (STAMP)
for Segment Routing Networks", Work in Progress, Internet-
Draft, draft-ietf-spring-stamp-srpm-09, 7 August 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
stamp-srpm-09>.
[I-D.ietf-spring-mpls-path-segment]
Cheng, W., Li, H., Li, C., Gandhi, R., and R. Zigler,
"Path Segment in MPLS Based Segment Routing Network", Work
in Progress, Internet-Draft, draft-ietf-spring-mpls-path-
segment-11, 29 August 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
mpls-path-segment-11>.
[I-D.ietf-spring-srv6-path-segment]
Li, C., Cheng, W., Chen, M., Dhody, D., and Y. Zhu, "Path
Segment for SRv6 (Segment Routing in IPv6)", Work in
Progress, Internet-Draft, draft-ietf-spring-srv6-path-
segment-06, 4 May 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
srv6-path-segment-06>.
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[I-D.ietf-pce-pcep-yang]
Dhody, D., Beeram, V. P., Hardwick, J., and J. Tantsura,
"A YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", Work in Progress,
Internet-Draft, draft-ietf-pce-pcep-yang-21, 6 March 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-pce-
pcep-yang-21>.
[I-D.ietf-pce-pcep-stateful-pce-gmpls]
Lee, Y., Zheng, H., de Dios, O. G., Lopez, V., and Z. Ali,
"Path Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE Usage in GMPLS-controlled
Networks", Work in Progress, Internet-Draft, draft-ietf-
pce-pcep-stateful-pce-gmpls-23, 20 August 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-pce-
pcep-stateful-pce-gmpls-23>.
[I-D.ietf-pce-multipath]
Koldychev, M., Sivabalan, S., Saad, T., Beeram, V. P.,
Bidgoli, H., Yadav, B., Peng, S., and G. S. Mishra, "PCEP
Extensions for Signaling Multipath Information", Work in
Progress, Internet-Draft, draft-ietf-pce-multipath-09, 24
July 2023, <https://datatracker.ietf.org/doc/html/draft-
ietf-pce-multipath-09>.
Acknowledgments
Many thanks to Marina Fizgeer, Adrian Farrel, Andrew Stone, Tarek
Saad, and Mike Koldychev 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: c.l@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
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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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