Internet DRAFT - draft-ietf-pce-pcep-stateful-pce-gmpls
draft-ietf-pce-pcep-stateful-pce-gmpls
PCE Working Group Y. Lee
Internet-Draft Samsung
Intended status: Standards Track H. Zheng
Expires: 21 February 2024 Huawei Technologies
O. Gonzalez de Dios
Telefonica
V. Lopez
Nokia
Z. Ali
Cisco
20 August 2023
Path Computation Element Communication Protocol (PCEP) Extensions for
Stateful PCE Usage in GMPLS-controlled Networks
draft-ietf-pce-pcep-stateful-pce-gmpls-23
Abstract
The PCE communication Protocol (PCEP) has been extended to support
stateful PCE functions where the Stateful PCE maintains information
about paths and resource usage within a network, but these extensions
do not cover all requirements for GMPLS networks.
This document provides the extensions required for PCEP so as to
enable the usage of a stateful PCE capability in GMPLS-controlled
networks.
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 21 February 2024.
Lee, et al. Expires 21 February 2024 [Page 1]
Internet-Draft Stateful PCEP for GMPLS August 2023
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/
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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions Used in this Document . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. General Context of Stateful PCE and PCEP for GMPLS . . . . . 4
4. Main Requirements . . . . . . . . . . . . . . . . . . . . . . 5
5. Overview of Stateful PCEP Extensions for GMPLS Networks . . . 6
5.1. Capability Advertisement for Stateful PCEP in GMPLS . . . 6
5.2. LSP Synchronization . . . . . . . . . . . . . . . . . . . 6
5.3. LSP Delegation and Cleanup . . . . . . . . . . . . . . . 7
5.4. LSP Operations . . . . . . . . . . . . . . . . . . . . . 7
6. PCEP Object Extensions . . . . . . . . . . . . . . . . . . . 7
6.1. Existing Extensions used for Stateful GMPLS . . . . . . . 7
6.2. New Extensions . . . . . . . . . . . . . . . . . . . . . 8
6.2.1. GMPLS-CAPABILITY TLV in OPEN Object . . . . . . . . . 8
6.2.2. New LSP Exclusion Sub-object in the XRO . . . . . . . 9
6.2.3. New flags in the LSP-EXTENDED-FLAG TLV in LSP
Object . . . . . . . . . . . . . . . . . . . . . . . 11
7. Update to Error Handling . . . . . . . . . . . . . . . . . . 11
7.1. Error Handling in PCEP Capabilities Advertisement . . . . 11
7.2. Error Handling in LSP Re-optimization . . . . . . . . . . 12
7.3. Error Handling in Route Exclusion . . . . . . . . . . . . 12
7.4. Error Handling for generalized END-POINTS . . . . . . . . 13
8. Implementation . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Huawei Technologies . . . . . . . . . . . . . . . . . . . 14
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9.1. title=New Flags in GMPLS-CAPABILITY TLV . . . . . . . . . 14
9.2. New Sub-object for the Exclude Route Object . . . . . . . 14
9.3. Flags Field for LSP exclusion Sub-object . . . . . . . . 15
9.4. New Flags in the LSP-EXTENDED-FLAGS TLV . . . . . . . . . 15
9.5. New PCEP Error Codes . . . . . . . . . . . . . . . . . . 16
10. Manageability Considerations . . . . . . . . . . . . . . . . 16
10.1. Control of Function through Configuration and Policy . . 17
Lee, et al. Expires 21 February 2024 [Page 2]
Internet-Draft Stateful PCEP for GMPLS August 2023
10.2. Information and Data Models . . . . . . . . . . . . . . 17
10.3. Liveness Detection and Monitoring . . . . . . . . . . . 17
10.4. Verifying Correct Operation . . . . . . . . . . . . . . 18
10.5. Requirements on Other Protocols and Functional
Components . . . . . . . . . . . . . . . . . . . . . . . 18
10.6. Impact on Network Operation . . . . . . . . . . . . . . 18
11. Security Considerations . . . . . . . . . . . . . . . . . . . 18
12. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 18
13. Nomative References . . . . . . . . . . . . . . . . . . . . . 18
14. Informative References . . . . . . . . . . . . . . . . . . . 20
Appendix A. Contributors' Address . . . . . . . . . . . . . . . 22
Appendix B. PCEP Messages . . . . . . . . . . . . . . . . . . . 23
B.1. The PCRpt Message . . . . . . . . . . . . . . . . . . . . 24
B.2. The PCUpd Message . . . . . . . . . . . . . . . . . . . . 25
B.3. The PCInitiate Message . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
1. Introduction
[RFC4655] presents the architecture of a Path Computation Element
(PCE)-based model for computing Multiprotocol Label Switching (MPLS)
and Generalized MPLS (GMPLS) Traffic Engineering Label Switched Paths
(TE LSPs). To perform such a constrained computation, a PCE stores
the network topology (i.e., TE links and nodes) and resource
information (i.e., TE attributes) in its TE Database (TED). A PCE
that only maintains TED is referred to as a stateless PCE. [RFC5440]
describes the Path Computation Element Communication Protocol (PCEP)
for interaction between a Path Computation Client (PCC) and a PCE, or
between two PCEs, enabling computation of TE LSPs. PCEP is further
extended to support GMPLS-controlled networks as per [RFC8779].
Stateful PCEs are shown to be helpful in many application scenarios,
in both MPLS and GMPLS networks, as illustrated in [RFC8051].
Further discussion of concept of a stateful PCE can be found in
[RFC7399]. In order for these applications to able to exploit the
capability of stateful PCEs, extensions to stateful PCEP for GMPLS
are required.
[RFC8051] describes how a stateful PCE can be applicable to solve
various problems for MPLS-TE and GMPLS networks and the benefits it
brings to such deployments.
[RFC8231] specifies a set of extensions to PCEP to enable stateful
control of TE LSPs where they are configured on the PCC, and control
over them could be delegated to the PCE. Furthermore, [RFC8281]
describes the setup and teardown of PCE-initiated LSPs under the
active stateful PCE model, without the need for local configuration
on the PCC. However, both documents omit the specification for
Lee, et al. Expires 21 February 2024 [Page 3]
Internet-Draft Stateful PCEP for GMPLS August 2023
technology-specific objects/TLVs, and do not cover GMPLS-controlled
networks (e.g., Wavelength Switched Optical Network (WSON), Optical
Transport Network (OTN), Synchronous Optical Network
(SONET)/Synchronous Digital Hierarchy (SDH), etc. technologies).
This document focuses on the extensions that are necessary in order
for the deployment of stateful PCEs and the requirements for PCE-
initiated LSPs in GMPLS-controlled networks. Section 3 provides a
general context of the usage of Stateful PCE and PCEP for GMPLS. The
various requirements for stateful GMPLS, including PCE-initiation for
GMPLS LSPs, are provided in Section 4. An overview of the PCEP
extensions is specified in Section 5, and a solution to address such
requirements with PCEP object extensions in Section 6.
1.1. Conventions Used in this Document
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.
2. Terminology
Terminology used in this document is the same as terminology used in
[RFC5440], [RFC8231], [RFC8281], and [RFC8779].
3. General Context of Stateful PCE and PCEP for GMPLS
This section is built on the basis of Stateful PCE specified in
[RFC8231] and PCEP for GMPLS specified in [RFC8779].
The operation for Stateful PCE on LSPs can be divided into two types,
active stateful PCE and passive stateful PCE as described in
[RFC8051].
For active stateful PCE, a Path Computation Update Request (PCUpd)
message is sent from PCE to PCC to update the LSP state for the LSPs
delegated to the PCE. Any changes to the delegated LSPs generate a
Path Computation State Report (PCRpt) message from the PCC to PCE to
convey the changes of the LSPs. Any modifications to the Objects/
TLVs that are identified in this document to support GMPLS
technology-specific attributes will be carried in the PCRpt and PCUpd
messages.
For passive stateful PCEs, Path Computation Request (PCReq)/ Path
Computation Reply (PCRep) messages are used to request for path
computation. GMPLS-technology specific Objects and TLVs are defined
Lee, et al. Expires 21 February 2024 [Page 4]
Internet-Draft Stateful PCEP for GMPLS August 2023
in [RFC8779], this document builds on it and adds the stateful PCE
aspects where applicable. Passive Stateful PCE makes use of PCRpt
messages when reporting LSP State changes sent by PCCs to PCEs. Any
modifications to the Objects/TLVs that are identified in this
document to support GMPLS technology-specific attributes will be
carried in the PCRpt message.
Furthermore, the LSP Initiation function of PCEP is defined in
[RFC8281] to allow the PCE to initiate LSP establishment after the
path is computed. An LSP Initiate Request (PCInitiate) message is
used to trigger the end node to set up the LSP. Any modifications to
the Objects/TLVs that are identified in this document to support
GMPLS technology-specific attributes will be carried in the
PCInitiate messages.
[RFC8779] defines GMPLS-technology specific Objects/TLVs in stateless
PCEP, and this document makes use of these Objects/TLVs without
modifications where applicable. Where these Objects/TLVs require
modifications to incorporate stateful PCE, they are described in this
document. PCE-Initiated LSPs follow the principle specified in
[RFC8281], and the GMPLS-specific extensions are also included in
this document.
4. Main Requirements
This section notes the main functional requirements for PCEP
extensions to support stateful PCE for use in GMPLS-controlled
networks, based on the description in [RFC8051]. Many requirements
are common across a variety of network types (e.g., MPLS-TE networks
and GMPLS networks) and the protocol extensions to meet the
requirements are already described in [RFC8231], such as LSP update,
delegation and state synchronization/report. Protection context
information that describes the GMPLS requirement can also follow the
description in [RFC8745]. This document does not repeat the
description of those protocol extensions. This document presents
protocol extensions for a set of requirements which are specific to
the use of a stateful PCE in a GMPLS-controlled network.
The requirements for GMPLS-specific stateful PCE are as follows:
* Advertisement of the stateful PCE capability. This generic
requirement is covered in Section 5.4 of [RFC8231]. The GMPLS-
CAPABILITY TLV specified in section 2.1 of [RFC8779] and its
extension in this document needs to be advertised as well.
* All the PCEP messages need to be capable of indicating GMPLS-
specific switching capabilities. GMPLS LSP creation/modification/
deletion requires knowledge of LSP switching capability (e.g.,
Lee, et al. Expires 21 February 2024 [Page 5]
Internet-Draft Stateful PCEP for GMPLS August 2023
Time-Division Multiplex Capable (TDM), Layer 2 Switch Capable
(L2SC), OTN-TDM, Lambda Switch Capable (LSC), etc.) and the
generalized payload (G-PID) to be used according to [RFC3471],
[RFC3473]. It also requires the specification of data flow
specific traffic parameters (also known as Traffic Specification
(Tspec)), which are technology specific. Such information would
need to be included in various PCEP messages.
* In some technologies, path calculation is tightly coupled with
label selection along the route. For example, path calculation in
a Wavelength Division Multiplexing (WDM) network may include
lambda continuity and/or lambda feasibility constraints and hence
a path computed by the PCE is associated with a specific lambda
(label). Hence, in such networks, the label information needs to
be provided to a PCC in order for a PCE to initiate GMPLS LSPs
under the active stateful PCE model, i.e., explicit label control
may be required.
* Stateful PCEP messages also need to indicate the protection
context information for the LSP specified by GMPLS, as defined in
[RFC4872], [RFC4873].
5. Overview of Stateful PCEP Extensions for GMPLS Networks
5.1. Capability Advertisement for Stateful PCEP in GMPLS
Capability Advertisement has been specified in [RFC8231], and can be
achieved by using the "STATEFUL-PCE-CAPABILITY TLV" in the Open
message. Another GMPLS-CAPABILITY TLV has been defined in [RFC8779].
A subregistry to manage the Flag field of the GMPLS-CAPABILITY TLV is
created by the IANA as requested by [RFC8779]. The following bits
are introduced by this document in the GMPLS-CAPABILITY TLV as flags
to indicate the capability for LSP report, update and initiation in
GMPLS networks: LSP-REPORT-CAPABILITY(TBDa), LSP-UPDATE-CAPABILITY
(TBD1), and LSP-INSTANTIATION-CAPABILITY (TBD2).
5.2. LSP Synchronization
After the session between the PCC and a stateful PCE is initialized,
the PCE must learn the state of a PCC's LSPs (including its
attributes) before it can perform path computations or update LSP
attributes in a PCC. This process is known as LSP state
synchronization. The LSP attributes including bandwidth, associated
route, and protection information etc., are stored by the PCE in the
LSP database (LSP-DB). Note that, as described in [RFC8231], the LSP
state synchronization covers both the bulk reporting of LSPs at
initialization as well the reporting of new or modified LSPs during
normal operation. Incremental LSP-DB synchronization may be desired
Lee, et al. Expires 21 February 2024 [Page 6]
Internet-Draft Stateful PCEP for GMPLS August 2023
in a GMPLS-controlled network and it is specified in [RFC8232].
The format of the PCRpt message is specified in [RFC8231] and
extended in [RFC8623] to include the END-POINTS object. The END-
POINTS object is extended for GMPLS in [RFC8779]. The END-POINTS
object can be carried in the PCRpt message as specified in [RFC8623].
The END-POINTS object type for GMPLS is included in the PCRpt message
as per the same.
The BANDWIDTH, LSP Attributes (LSPA), Include Route Object (IRO) and
Exclude Route Object (XRO) objects are extended for GMPLS in
[RFC8779] and are also used in the PCRpt in the same manner. These
objects are carried in the PCRpt message as specified in [RFC8231]
(as the attribute-list defined in Section 6.5 of [RFC5440] and
extended by many other documents that define PCEP extensions for
specific scenarios).
The SWITCH-LAYER object is defined in [RFC8282]. This object is
carried in PCRpt message as specified in section 3.2 of [RFC8282].
5.3. LSP Delegation and Cleanup
LSP delegation and cleanup procedure specified in [RFC8231] are
equally applicable to GMPLS LSPs and this document does not modify
the associated usage.
5.4. LSP Operations
Both passive and active stateful PCE mechanisms in [RFC8231] are
applicable in GMPLS-controlled networks. Remote LSP Initiation in
[RFC8281] is also applicable in GMPLS-controlled networks.
6. PCEP Object Extensions
6.1. Existing Extensions used for Stateful GMPLS
Existing extensions defined in [RFC8779] can be used in Stateful PCEP
with no or slight changes for GMPLS network control, including the
following:
* END-POINTS: Generalized END-POINTS was specified in [RFC8779] to
include GMPLS capabilities. All Stateful PCEP messages MUST
include the END-POINTS with Generalized Endpoint object type,
containing the LABEL-REQUEST TLV. Further note that:
Lee, et al. Expires 21 February 2024 [Page 7]
Internet-Draft Stateful PCEP for GMPLS August 2023
- As per [RFC8779] for stateless GMPLS path computation, the
Generalized END-POINTS object may contain a LABEL-REQUEST and/
or LABEL-SET TLV. In this document, only the LABEL-REQUEST TLV
is used to specify the switching type, encoding type and G-PID
of the LSP.
- If unnumbered endpoint addresses are used for the LSP, the
UNNUMBERED-ENDPOINT TLV [RFC8779] MUST be used to specify the
unnumbered endpoint addresses.
- The Generalized END-POINTS MAY contain other TLVs defined in
[RFC8779].
* RP: RP object extension, together with the Routing Granularity
(RG) flag defined in [RFC8779], are applicable in the Stateful
PCEP for GMPLS networks.
* BANDWIDTH: Generalized BANDWIDTH was specified in [RFC8779] to
represent GMPLS features, including asymmetric bandwidth and G-PID
information.
* LSPA: LSPA Extensions in Section 2.8 of [RFC8779] is applicable in
Stateful PCEP for GMPLS networks.
* IRO: IRO Extensions in Section 2.6 of [RFC8779] is applicable in
Stateful PCEP for GMPLS networks.
* XRO: XRO Extensions in Section 2.7 of [RFC8779] is applicable in
Stateful PCEP for GMPLS networks. A new flag is defined in
Section 6.2.3 of this document.
* ERO: The Explicit Route Object (ERO) was not extended in
[RFC8779], nor is it in this document.
* SWITCH-LAYER: SWITCHING-LAYER definition in Section 3.2 of
[RFC8282] is applicable in Stateful PCEP messages for GMPLS
networks.
6.2. New Extensions
6.2.1. GMPLS-CAPABILITY TLV in OPEN Object
In [RFC8779], IANA has allocated value 45 (GMPLS-CAPABILITY) from the
"PCEP TLV Type Indicators" sub-registry. The specifcation add three
flags to the flag field of this TLV to indicate the Report, Update,
and Initiation capabilities.
Lee, et al. Expires 21 February 2024 [Page 8]
Internet-Draft Stateful PCEP for GMPLS August 2023
R (LSP-REPORT-CAPABILITY(TBDa) -- 1 bit): if set to 1 by a PCC, the R
flag indicates that the PCC is capable of reporting the current state
of a GMPLS LSP, whenever there's a change to the parameters or
operational status of the GMPLS LSP; if set to 1 by a PCE, the R Flag
indicates that the PCE is interested in receiving GMPLS LSP State
Reports whenever there is a parameter or operational status change to
the LSP. The LSP-REPORT-CAPABILITY flag must be advertised by both a
PCC and a PCE for PCRpt messages to be allowed on a PCEP session for
GMPLS LSP.
U (LSP-UPDATE-CAPABILITY(TBD1) -- 1 bit): if set to 1 by a PCC, the U
flag indicates that the PCC allows modification of GMPLS LSP
parameters; if set to 1 by a PCE, the U flag indicates that the PCE
is capable of updating GMPLS LSP parameters. The LSP-UPDATE-
CAPABILITY flag must be advertised by both a PCC and a PCE for PCUpd
messages to be allowed on a PCEP session for GMPLS LSP.
I (LSP-INSTANTIATION-CAPABILITY(TBD2) -- 1 bit): If set to 1 by a
PCC, the I flag indicates that the PCC allows instantiation of a
GMPLS LSP by a PCE. If set to 1 by a PCE, the I flag indicates that
the PCE supports instantiating GMPLS LSPs. The LSP-INSTANTIATION-
CAPABILITY flag must be set by both the PCC and PCE in order to
enable PCE-initiated LSP instantiation.
6.2.2. New LSP Exclusion Sub-object in the XRO
[RFC5521] defines a mechanism for a PCC to request or demand that
specific nodes, links, or other network resources are excluded from
paths computed by a PCE. A PCC may wish to request the computation
of a path that avoids all links and nodes traversed by some other
LSP.
To this end this document defines a new sub-object for use with route
exclusion defined in [RFC5521]. The LSP exclusion sub-object is as
follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X|Type (TBD3) | Length | Reserved | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Symbolic Path Name //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Lee, et al. Expires 21 February 2024 [Page 9]
Internet-Draft Stateful PCEP for GMPLS August 2023
Figure 1: New LSP Exclusion Sub-object Format
X: Same as the X-bit defined in the XRO sub-objects in Section 2.1.1
of [RFC5521] where it says: "The X-bit indicates whether the
exclusion is mandatory or desired. 0 indicates that the resource
specified MUST be excluded from the path computed by the PCE. 1
indicates that the resource specified SHOULD be excluded from the
path computed by the PCE, but MAY be included subject to PCE policy
and the absence of a viable path that meets the other constraints and
excludes the resource.".
Type: Sub-object Type for an LSP exclusion sub-object. Value of
TBD3. To be assigned by IANA.
Length: The Length contains the total length of the sub-object in
bytes, including the Type and Length fields.
Reserved: MUST be set to zero on transmission and ignored on receipt.
Flags: This field may be used to further specify the exclusion
constraint with regard to the LSP. Currently, no flags are defined.
Symbolic Path Name: This is the identifier given to an LSP. Its
syntax and semantics are identical to those of the Symbolic Path Name
field defined in Section 7.3.2 of [RFC8231] where it says: "symbolic
name for the LSP, unique in the PCC. It SHOULD be a string of
printable ASCII characters, without a NULL terminator." The Symbolic
Path Name in the LSP Exclusion Sub-object MUST only vary from being a
string of printable ASCII characters without a NULL terminator when
it is matching the value contained in another subobject. It is worth
noting that given that the Symbolic Path Name is unique in the
context of the headnode, only LSPs that share the same headnode/PCC
could be excluded.
This sub-object MAY be present multiple times in the exclude route
object (XRO) to exclude resources from multiple LSPs. When a
stateful PCE receives a PCReq message carrying this sub-object, it
MUST search for the identified LSP in its LSP-DB and then exclude
from the new path computation all resources used by the identified
LSP.
Note that this XRO Sub-object could also be used by non-GMPLS LSPs.
The description by usage of non-GMPLS LSPs is not in the scope of
this document.
Lee, et al. Expires 21 February 2024 [Page 10]
Internet-Draft Stateful PCEP for GMPLS August 2023
6.2.3. New flags in the LSP-EXTENDED-FLAG TLV in LSP Object
The LSP Object is defined in Section 7.3 of [RFC8231], and the new
extended flags TLV is defined in [RFC9357]. This TLV is used in
PCUpd, PCRpt and PCInitiate messages for GMPLS, with the following
flags defined in this document.
* G (GMPLS LSP(TBDb) -- 1 bit) : If set to 1, it indicates the LSP
is a GMPLS LSP.
* B (Bidirectional LSP(TBD4) -- 1 bit): If set to 0, it indicates a
request to create a uni-directional LSP. If set to 1, it
indicates a request to create a bidirectional co-routed LSP.
* RG (Routing Granularity(TBDc) -- 2 bits) : RG flag for GMPLS is
also defined in the LSP-EXTENDED-FLAG TLV. The value are defined
as per [RFC8779]:
00: reserved
01: node
10: link
11: label
7. Update to Error Handling
A PCEP-ERROR object is used to report a PCEP error and is
characterized by an Error-Type that specifies the type of error and
an Error-value that provides additional information about the error.
This section adds additional error handling procedures to those
specified in Section 3 of [RFC8779]. Please note that all error
handling specified in Section 3 of [RFC8779] is applicable and MUST
be supported for a stateful PCE in GMPLS networks.
7.1. Error Handling in PCEP Capabilities Advertisement
The PCEP extensions described in this document for stateful PCEs with
GMPLS capability MUST NOT be used if the PCE has not advertised its
capabilities with GMPLS as per Section 6.2.1.
Lee, et al. Expires 21 February 2024 [Page 11]
Internet-Draft Stateful PCEP for GMPLS August 2023
If the PCC understands the U flag that indicates the stateful LSP-
UPDATE-CAPABILITY, but did not advertise this capability, then upon
receipt of a PCUpd message for GMPLS LSP from the PCE, it SHOULD
generate a PCErr with error-type 19 ("Invalid Operation"), error-
value TBDx ("Attempted LSP Update Request for GMPLS if stateful PCE
capability for GMPLS was not advertised"), and terminate the PCEP
session. Such a PCC MAY decide to utilize the capability even though
it did not advertise support for it.
If the PCE understands the R flag that indicates the stateful LSP-
REPORT-CAPABILITY, but did not advertise this capability, then upon
receipt of a PCRpt message for GMPLS LSP from the PCC, it SHOULD
generate a PCErr with error-type 19 ("Invalid Operation"), error-
value TBDy ("Attempted LSP Report Request for GMPLS if stateful PCE
capability for GMPLS was not advertised"), and terminate the PCEP
session. Such a PCE MAY decide to utilize the capability even though
it did not advertise support for it.
If the PCC understands the I flag that indicates LSP-INSTANTIATION-
CAPABILITY, but did not advertise this capability, then upon receipt
of a PCInitiate message for GMPLS LSP from the PCE, it SHOULD
generate a PCErr with error-type 19 ("Invalid Operation"), error-
value TBDz ("Attempted LSP Instantiation Request for GMPLS if
stateful PCE instantiation capability for GMPLS was not advertised"),
and terminate the PCEP session. Such a PCC MAY decide to utilize the
capability even though it did not advertise support for it.
7.2. Error Handling in LSP Re-optimization
A stateful PCE is expected to perform an LSP re-optimization when
receiving a message with the R bit set in the RP object. If no LSP
state information is available to carry out re-optimization, the
stateful PCE SHOULD report the error "LSP state information
unavailable for the LSP re-optimization" (Error Type = 19, Error
value= TBD6), although such a PCE MAY consider the re-optimization to
have successfully completed. Note that this error message could also
be used by non-GMPLS LSPs.
7.3. Error Handling in Route Exclusion
The LSP exclusion sub-object in XRO is defined in Section 6.2.2 of
this document MAY be present multiple times. When a stateful PCE
receives a PCEP message carrying this sub-object, it searches for the
identified LSP in its LSP-DB and then excludes from the new path
computation all the resources used by the identified LSP. If the
stateful PCE cannot recognize the symbolic path name of the
identified LSP, it SHOULD send an error message PCErr reporting
Error-type = 19 ("Invalid Operation"), Error-value = TBD7 ("The LSP
Lee, et al. Expires 21 February 2024 [Page 12]
Internet-Draft Stateful PCEP for GMPLS August 2023
state information for route exclusion purpose cannot be found").
Optionally, it MAY also provide with the unrecognized symbolic path
name information to the requesting PCC using the error reporting
techniques described in [RFC5440]. An implementation MAY choose to
ignore the requested exclusion when the LSP cannot be found because
it could claim it that it has avoided using all resources associated
with an LSP that doesn't exist.
7.4. Error Handling for generalized END-POINTS
Note that the END-POINTS object in the Stateful PCEP messages was
introduced for P2MP [RFC8623]. Similarly, the END-POINTS object MUST
be carried for the GMPLS LSP. If the END-POINTS object is missing
and the GMPLS flag in LSP-EXTENDED-FLAG is set, the receiving PCE or
PCC MUST send a PCErr message with Error-type=6 ("Mandatory Object
missing") and Error-value=3 ("END-POINTS object missing") (defined in
[RFC5440]). Similarly, if the END-POINTS object with the Generalized
Endpoint object type is received but if the LSP-EXTENDED-FLAG TLV is
missing in the LSP object or if the G flag in the LSP-EXTENDED-FLAG
TLV is not set, the receiving PCE or PCC MUST send a PCErr message
with Error-type = 19 ("Invalid Operation"), Error-value = TBD9 ("Use
of Generalized Endpoint object type for non-GMPLS LSP").
If the END-POINTS object with Generalized Endpoint Object Type is
missing the LABEL-REQUEST TLV, the receiving PCE or PCC MUST send a
PCErr message with Error-type=6 ("Mandatory Object missing") and
Error-value=TBD8 ("LABEL-REQUEST TLV missing").
8. Implementation
[NOTE TO RFC EDITOR : This whole section and the reference to RFC
7942 is to be removed before publication as an RFC]
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.
Lee, et al. Expires 21 February 2024 [Page 13]
Internet-Draft Stateful PCEP for GMPLS August 2023
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".
8.1. Huawei Technologies
* Organization: Huawei Technologies, Co. LTD
* Implementation: Huawei NCE-T
* Description: PCRpt, PCUpd and PCInitiate messages for GMPLS
Network
* Maturity Level: Production
* Coverage: Full
* Contact: zhenghaomian@huawei.com
9. IANA Considerations
9.1. title=New Flags in GMPLS-CAPABILITY TLV
[RFC8779] defines the GMPLS-CAPABILITY TLV; per that RFC, IANA
created a registry to manage the value of the GMPLS-CAPABILITY TLV's
Flag field. This document requests IANA to allocate new bits in the
GMPLS-CAPABILITY TLV Flag Field registry, as follows. IANA is
requested to make allocations starting from the least significant bit
(31).
Bit | Description | Reference
-----+----------------------------------+------------
TBDa | LSP-REPORT-CAPABILITY (R) | [This.I-D]
TBD1 | LSP-UPDATE-CAPABILITY (U) | [This.I-D]
TBD2 | LSP-INSTANTIATION-CAPABILITY (I) | [This.I-D]
9.2. New Sub-object for the Exclude Route Object
IANA maintains the various XRO Subobjects types within the "XRO
Subobjects" subregistry of the PCEP Numbers registry. IANA is
requested to allocate a codepoint for another XRO subobject as
follows:
Lee, et al. Expires 21 February 2024 [Page 14]
Internet-Draft Stateful PCEP for GMPLS August 2023
Value | Description | Reference
--------+------------------------------+-------------
TBD3 | LSP | [This.I-D]
9.3. Flags Field for LSP exclusion Sub-object
IANA is requested to create a registry named "LSP Exclusion Sub-
Object Flag Field", within the "Path Computation Element Protocol
(PCEP) Numbers" group, to manage the Flag field of the LSP Exclusion
sub-object in the XRO. No Flag is currently defined for this flag
field in this document.
Codespace of the Flag field (LSP Exclusion sub-object)
Bit | Description | Reference
------+-------------------+-------------
0-7 | Unassigned | [This.I-D]
New values are to be assigned by Standards Action [RFC8126]. Each
bit should be tracked with the following qualities:
* Bit number (counting from bit 0 as the most significant bit)
* Capability description
* Defining RFC
9.4. New Flags in the LSP-EXTENDED-FLAGS TLV
[I-D.ietf-pce-lsp-extended-flags] requested IANA to create a
subregistry, named the "LSP-EXTENDED-FLAG TLV Flag Field", within the
"Path Computation Element Protocol (PCEP) Numbers" registry, to
manage the Flag field of the LSP-EXTENDED-FLAG TLV.
IANA is requested to make assignments from this registry as follows:
Bit | Description | Reference
------+----------------------------------+------------
TBDb | GMPLS LSP (G) | [This.I-D]
TBD4 | Bi-directional co-routed LSP (B) | [This.I-D]
TBDc* | Routing Granularity Flag (RG) | [This.I-D]
* - 2 bits need to be allocated
Lee, et al. Expires 21 February 2024 [Page 15]
Internet-Draft Stateful PCEP for GMPLS August 2023
9.5. New PCEP Error Codes
IANA is requested to make the following allocation in the "PCEP-ERROR
Object Error Types and Values" registry.
+===========+================+=========================+===========+
| Error-Type| Meaning | Error-value | Reference |
+===========+================+=========================+===========+
| 6 | Mandatory |TBD8: LABEL-REQUEST TLV | This I-D |
| | Object missing |missing | |
|-----------|----------------+-------------------------+-----------+
|19 | Invalid |TBD6: LSP state info | This I-D |
| | Operation |unavailable for the | |
| | |Re-optimization | |
| | +-------------------------+-----------+
| | |TBD7: LSP state info for | This I-D |
| | |route exclusion not found| |
| | +-------------------------+-----------+
| | |TBDx: Attempted LSP | This I-D |
| | |Update Request for GMPLS | |
| | |if stateful PCE | |
| | |capability not advertised| |
| | +-------------------------+-----------+
| | |TBDy: Attempted LSP State| This I-D |
| | |Report for GMPLS if | |
| | |stateful PCE capability | |
| | |not advertised | |
| | +-------------------------+-----------+
| | |TBDz: Attempted LSP | This I-D |
| | |Instantiation Request for| |
| | |GMPLS if stateful PCE | |
| | |instantiation capability | |
| | |not advertised | |
| | +-------------------------+-----------+
| | |TBD9: use of Generalized | This I-D |
| | |Endpoint object type for | |
| | |non-GMPLS LSP | |
+-----------+----------------+-------------------------+-----------+
10. Manageability Considerations
General PCE management considerations are discussed in [RFC4655] and
[RFC5440], and GMPLS specific PCEP management considerations are
described in [RFC8779]. In this document the management
considerations for stateful PCEP extension in GMPLS are described.
Lee, et al. Expires 21 February 2024 [Page 16]
Internet-Draft Stateful PCEP for GMPLS August 2023
This section follows the guidance of [RFC6123].
10.1. Control of Function through Configuration and Policy
In addition to the parameters already listed in Section 8.1 of
[RFC5440], a PCEP implementation SHOULD allow configuration of the
following PCEP session parameters on a PCC, however, an
implementation MAY choose to make these features available on all
PCEP sessions:
* The ability to send stateful PCEP messages for GMPLS LSPs.
* The ability to use path computation constraints (e.g., XRO).
In addition to the parameters already listed in Section 8.1 of
[RFC5440], a PCEP implementation SHOULD allow configuration of the
following PCEP session parameters on a PCE:
* The ability to compute paths in a stateful manner in GMPLS
networks.
* A set of GMPLS-specific constraints.
These parameters may be configured as default parameters for any PCEP
session the PCEP speaker participates in, or they may apply to a
specific session with a given PCEP peer or a specific group of
sessions with a specific group of PCEP peers.
10.2. Information and Data Models
The YANG model in [I-D.ietf-pce-pcep-yang] can be used to configure
and monitor PCEP states and messages. To make sure that the YANG
model is useful for the extensions as described in this document, it
would need to include advertised GMPLS stateful capabilities etc. A
future version of [I-D.ietf-pce-pcep-yang] will include this.
As described in [I-D.ietf-teas-yang-path-computation], a YANG-based
interface can be used in some cases to request GMPLS path
computations, instead of PCEP. Refer
[I-D.ietf-teas-yang-path-computation] for details.
10.3. Liveness Detection and Monitoring
This document makes no change to the basic operation of PCEP, so
there are no changes to the requirements for liveness detection and
monitoring in [RFC4657] and Section 8.3 of [RFC5440].
Lee, et al. Expires 21 February 2024 [Page 17]
Internet-Draft Stateful PCEP for GMPLS August 2023
10.4. Verifying Correct Operation
This document makes no change to the basic operations of PCEP and the
considerations described in Section 8.4 of [RFC5440]. New errors
defined by this document should satisfy the requirement to log error
events.
10.5. Requirements on Other Protocols and Functional Components
When the detailed route information is included for LSP state
synchronization (either at the initial stage or during LSP state
report process), this requires the ingress node of an LSP to carry
the RRO object in order to enable the collection of such information.
10.6. Impact on Network Operation
The management considerations concerning the impact on network
operations described in Section 4.6 of [RFC8779] apply here.
11. Security Considerations
The security considerations elaborated in [RFC5440] apply to this
document. The PCEP extensions to support GMPLS-controlled networks
should be considered under the same security as for MPLS networks, as
noted in [RFC7025]. So the PCEP extension to support GMPLS specified
in [RFC8779] is used as the foundation of this document and the
security considerations in [RFC8779] should also be applicable to
this document. The secure transport of PCEP specified in [RFC8253]
allows the usage of Transport Layer Security (TLS). The same can
also be used by the PCEP extension defined in this document.
This document provides additional extensions to PCEP so as to
facilitate stateful PCE usage in GMPLS-controlled networks, on top of
[RFC8231] and [RFC8281]. Security issues caused by the extension in
[RFC8231] and [RFC8281] are not altered by the additions in this
document. The security considerations in [RFC8231] and [RFC8281],
including both issues and solutions, apply to this document as well.
12. Acknowledgement
We would like to thank Adrian Farrel, Cyril Margaria, George Swallow,
Jan Medved, Sue Hares, and John Scudder for the useful comments and
discussions.
Thanks to Dhruv Dhody for Shepherding this document and providing
useful comments.
13. Nomative References
Lee, et al. Expires 21 February 2024 [Page 18]
Internet-Draft Stateful PCEP for GMPLS August 2023
[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>.
[RFC5521] Oki, E., Takeda, T., and A. Farrel, "Extensions to the
Path Computation Element Communication Protocol (PCEP) for
Route Exclusions", RFC 5521, DOI 10.17487/RFC5521, April
2009, <https://www.rfc-editor.org/info/rfc5521>.
[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>.
[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>.
[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>.
[RFC8779] Margaria, C., Ed., Gonzalez de Dios, O., Ed., and F.
Zhang, Ed., "Path Computation Element Communication
Protocol (PCEP) Extensions for GMPLS", RFC 8779,
DOI 10.17487/RFC8779, July 2020,
<https://www.rfc-editor.org/info/rfc8779>.
[RFC9357] Xiong, Q., "Label Switched Path (LSP) Object Flag
Extension for Stateful PCE", RFC 9357,
DOI 10.17487/RFC9357, February 2023,
<https://www.rfc-editor.org/info/rfc9357>.
Lee, et al. Expires 21 February 2024 [Page 19]
Internet-Draft Stateful PCEP for GMPLS August 2023
14. Informative References
[I-D.ietf-pce-lsp-extended-flags]
Xiong, Q., "Label Switched Path (LSP) Object Flag
Extension for Stateful PCE", Work in Progress, Internet-
Draft, draft-ietf-pce-lsp-extended-flags-09, 23 October
2022, <https://datatracker.ietf.org/doc/html/draft-ietf-
pce-lsp-extended-flags-09>.
[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-teas-yang-path-computation]
Busi, I., Belotti, S., de Dios, O. G., Sharma, A., and Y.
Shi, "A YANG Data Model for requesting path computation",
Work in Progress, Internet-Draft, draft-ietf-teas-yang-
path-computation-21, 7 July 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-teas-
yang-path-computation-21>.
[RFC3471] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description",
RFC 3471, DOI 10.17487/RFC3471, January 2003,
<https://www.rfc-editor.org/info/rfc3471>.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
DOI 10.17487/RFC3473, January 2003,
<https://www.rfc-editor.org/info/rfc3473>.
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC4657] Ash, J., Ed. and J.L. 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>.
Lee, et al. Expires 21 February 2024 [Page 20]
Internet-Draft Stateful PCEP for GMPLS August 2023
[RFC4872] Lang, J.P., Ed., Rekhter, Y., Ed., and D. Papadimitriou,
Ed., "RSVP-TE Extensions in Support of End-to-End
Generalized Multi-Protocol Label Switching (GMPLS)
Recovery", RFC 4872, DOI 10.17487/RFC4872, May 2007,
<https://www.rfc-editor.org/info/rfc4872>.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
"GMPLS Segment Recovery", RFC 4873, DOI 10.17487/RFC4873,
May 2007, <https://www.rfc-editor.org/info/rfc4873>.
[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in Various Routing Protocol
Specifications", RFC 5511, DOI 10.17487/RFC5511, April
2009, <https://www.rfc-editor.org/info/rfc5511>.
[RFC6123] Farrel, A., "Inclusion of Manageability Sections in Path
Computation Element (PCE) Working Group Drafts", RFC 6123,
DOI 10.17487/RFC6123, February 2011,
<https://www.rfc-editor.org/info/rfc6123>.
[RFC7025] Otani, T., Ogaki, K., Caviglia, D., Zhang, F., and C.
Margaria, "Requirements for GMPLS Applications of PCE",
RFC 7025, DOI 10.17487/RFC7025, September 2013,
<https://www.rfc-editor.org/info/rfc7025>.
[RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path
Computation Element Architecture", RFC 7399,
DOI 10.17487/RFC7399, October 2014,
<https://www.rfc-editor.org/info/rfc7399>.
[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>.
[RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
Stateful Path Computation Element (PCE)", RFC 8051,
DOI 10.17487/RFC8051, January 2017,
<https://www.rfc-editor.org/info/rfc8051>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
Lee, et al. Expires 21 February 2024 [Page 21]
Internet-Draft Stateful PCEP for GMPLS August 2023
[RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X.,
and D. Dhody, "Optimizations of Label Switched Path State
Synchronization Procedures for a Stateful PCE", RFC 8232,
DOI 10.17487/RFC8232, September 2017,
<https://www.rfc-editor.org/info/rfc8232>.
[RFC8282] Oki, E., Takeda, T., Farrel, A., and F. Zhang, "Extensions
to the Path Computation Element Communication Protocol
(PCEP) for Inter-Layer MPLS and GMPLS Traffic
Engineering", RFC 8282, DOI 10.17487/RFC8282, December
2017, <https://www.rfc-editor.org/info/rfc8282>.
[RFC8623] Palle, U., Dhody, D., Tanaka, Y., and V. Beeram, "Stateful
Path Computation Element (PCE) Protocol Extensions for
Usage with Point-to-Multipoint TE Label Switched Paths
(LSPs)", RFC 8623, DOI 10.17487/RFC8623, June 2019,
<https://www.rfc-editor.org/info/rfc8623>.
[RFC8745] Ananthakrishnan, H., Sivabalan, S., Barth, C., Minei, I.,
and M. Negi, "Path Computation Element Communication
Protocol (PCEP) Extensions for Associating Working and
Protection Label Switched Paths (LSPs) with Stateful PCE",
RFC 8745, DOI 10.17487/RFC8745, March 2020,
<https://www.rfc-editor.org/info/rfc8745>.
Appendix A. Contributors' Address
Lee, et al. Expires 21 February 2024 [Page 22]
Internet-Draft Stateful PCEP for GMPLS August 2023
Xian Zhang
Huawei Technologies
Email: zhang.xian@huawei.com
Dhruv Dhody
Huawei Technology
India
Email: dhruv.ietf@gmail.com
Yi Lin
Huawei Technologies
Email: yi.lin@huawei.com
Fatai Zhang
Huawei Technologies
Email: zhangfatai@huawei.com
Ramon Casellas
CTTC
Av. Carl Friedrich Gauss n7
Castelldefels, Barcelona 08860
Spain
Email: ramon.casellas@cttc.es
Siva Sivabalan
Cisco Systems
Email: msiva@cisco.com
Clarence Filsfils
Cisco Systems
Email: cfilsfil@cisco.com
Robert Varga
Pantheon Technologies
Email: nite@hq.sk
Appendix B. PCEP Messages
This section uses the Routing Backus-Naur Form (RBNF) [RFC5511] to
illustrate the PCEP messages. The RBNF in this section is reproduced
for informative purposes. It is also expanded to show the GMPLS
specific objects.
Lee, et al. Expires 21 February 2024 [Page 23]
Internet-Draft Stateful PCEP for GMPLS August 2023
B.1. The PCRpt Message
According to [RFC8231], the PCRpt Message is used to report the
current state of an LSP. This document extends the message in
reporting the status of LSPs with GMPLS characteristics.
The format of the PCRpt message is as follows:
<PCRpt Message> ::= <Common Header>
<state-report-list>
Where:
<state-report-list> ::= <state-report>[<state-report-list>]
<state-report> ::= [<SRP>]
<LSP>
[<END-POINTS>]
<path>
Where:
<path> ::= <intended-path>
[<actual-attribute-list><actual-path>]
<intended-attribute-list>
<actual-attribute-list> ::=[<BANDWIDTH>]
[<metric-list>]
Where:
* The END-POINTS object MUST be carried in a PCRpt message when the
G flag is set in the LSP-EXTENDED-FLAG TLV in the LSP object for a
GMPLS LSP.
* <intended-path> is represented by the ERO object defined in
Section 7.9 of [RFC5440], augmented in [RFC8779] with explicit
label control (ELC) and Path Keys.
* <actual-attribute-list> consists of the actual computed and
signaled values of the <BANDWIDTH> and <metric-lists> objects
defined in [RFC5440].
Lee, et al. Expires 21 February 2024 [Page 24]
Internet-Draft Stateful PCEP for GMPLS August 2023
* <actual-path> is represented by the RRO object defined in
Section 7.10 of [RFC5440].
* <intended-attribute-list> is the attribute-list defined in
Section 6.5 of [RFC5440] and extended by many other documents that
define PCEP extensions for specific scenarios as shown below:
<attribute-list> ::= [<of-list>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>][<XRO>]
[<INTER-LAYER>]
[<SWITCH-LAYER>]
[<REQ-ADAP-CAP>]
[<SERVER-INDICATION>]
B.2. The PCUpd Message
The format of a PCUpd message is as follows:
<PCUpd Message> ::= <Common Header>
<update-request-list>
Where:
<update-request-list> ::= <update-request>[<update-request-list>]
<update-request> ::= <SRP>
<LSP>
[<END-POINTS>]
<path>
Where:
<path> ::= <intended-path><intended-attribute-list>
Where:
* The END-POINTS object MUST be carried in a PCUpd message for the
GMPLS LSP.
Lee, et al. Expires 21 February 2024 [Page 25]
Internet-Draft Stateful PCEP for GMPLS August 2023
* <intended-path> is represented by the ERO object defined in
Section 7.9 of [RFC5440], augmented in [RFC8779] with explicit
label control (ELC) and Path Keys.
* <intended-attribute-list> is the attribute-list defined in
[RFC5440] and extended by many other documents that define PCEP
extensions for specific scenarios and as shown for PCRpt above.
B.3. The PCInitiate Message
According to [RFC8281], the PCInitiate Message is used allow LSP
Initiation. This document extends the message in initiating LSPs
with GMPLS characteristics. The format of a PCInitiate message is as
follows:
<PCInitiate Message> ::= <Common Header>
<PCE-initiated-lsp-list>
Where:
<Common Header> is defined in <xref target="RFC5440" />.
<PCE-initiated-lsp-list> ::= <PCE-initiated-lsp-request>
[<PCE-initiated-lsp-list>]
<PCE-initiated-lsp-request> ::= (<PCE-initiated-lsp-instantiation>|
<PCE-initiated-lsp-deletion>)
<PCE-initiated-lsp-instantiation> ::= <SRP>
<LSP>
[<END-POINTS>]
<ERO>
[<attribute-list>]
<PCE-initiated-lsp-deletion> ::= <SRP>
<LSP>
The format of the PCInitiate message is unchanged from Section 5.1 of
[RFC8281]. All fields are similar to the PCRpt and the PCUpd
message.
Authors' Addresses
Young Lee
Samsung
Email: younglee.tx@gmail.com
Lee, et al. Expires 21 February 2024 [Page 26]
Internet-Draft Stateful PCEP for GMPLS August 2023
Haomian Zheng
Huawei Technologies
Email: zhenghaomian@huawei.com
Oscar Gonzalez de Dios
Telefonica
Email: oscar.gonzalezdedios@telefonica.com
Victor Lopez
Nokia
Email: victor.lopez@nokia.com
Zafar Ali
Cisco
Email: zali@cisco.com
Lee, et al. Expires 21 February 2024 [Page 27]
