Internet DRAFT - draft-ietf-pce-stateful-pce-p2mp
draft-ietf-pce-stateful-pce-p2mp
PCE Working Group U. Palle
Internet-Draft D. Dhody
Intended status: Standards Track Huawei Technologies
Expires: October 14, 2019 Y. Tanaka
NTT Communications
V. Beeram
Juniper Networks
April 12, 2019
Path Computation Element (PCE) Protocol Extensions for Stateful PCE
usage for Point-to-Multipoint Traffic Engineering Label Switched Paths
draft-ietf-pce-stateful-pce-p2mp-13
Abstract
The Path Computation Element (PCE) has been identified as an
appropriate technology for the determination of the paths of point-
to-multipoint (P2MP) TE Label Switched Paths (LSPs). This document
provides extensions required for Path Computation Element
Communication Protocol (PCEP) so as to enable the usage of a stateful
PCE capability in supporting P2MP TE LSPs.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on October 14, 2019.
Copyright Notice
Copyright (c) 2019 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Supporting P2MP TE LSPs for Stateful PCE . . . . . . . . . . 4
3.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Objectives . . . . . . . . . . . . . . . . . . . . . . . 5
4. Functions to Support P2MP TE LSPs for Stateful PCEs . . . . . 5
5. Architectural Overview of Protocol Extensions . . . . . . . . 6
5.1. Extension of PCEP Messages . . . . . . . . . . . . . . . 6
5.2. Capability Advertisement . . . . . . . . . . . . . . . . 6
5.3. IGP Extensions for Stateful PCE P2MP Capabilities
Advertisement . . . . . . . . . . . . . . . . . . . . . . 7
5.4. State Synchronization . . . . . . . . . . . . . . . . . . 8
5.5. LSP Delegation . . . . . . . . . . . . . . . . . . . . . 8
5.6. LSP Operations . . . . . . . . . . . . . . . . . . . . . 8
5.6.1. Passive Stateful PCE . . . . . . . . . . . . . . . . 8
5.6.2. Active Stateful PCE . . . . . . . . . . . . . . . . . 9
5.6.3. PCE-Initiated LSP . . . . . . . . . . . . . . . . . . 9
5.6.3.1. P2MP TE LSPs Instantiation . . . . . . . . . . . 9
5.6.3.2. P2MP TE LSPs Deletion . . . . . . . . . . . . . . 9
5.6.3.3. Adding and Pruning Leaves for the P2MP TE LSP . . 10
5.6.3.4. P2MP TE LSPs Delegation and Cleanup . . . . . . . 10
6. PCEP Message Extensions . . . . . . . . . . . . . . . . . . . 10
6.1. The PCRpt Message . . . . . . . . . . . . . . . . . . . . 10
6.2. The PCUpd Message . . . . . . . . . . . . . . . . . . . . 13
6.3. The PCReq Message . . . . . . . . . . . . . . . . . . . . 14
6.4. The PCRep Message . . . . . . . . . . . . . . . . . . . . 14
6.5. The PCInitiate message . . . . . . . . . . . . . . . . . 15
6.6. Example . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.6.1. P2MP TE LSPs Update Request . . . . . . . . . . . . . 17
6.6.2. P2MP TE LSP Report . . . . . . . . . . . . . . . . . 17
6.6.3. P2MP TE LSPs Initiation Request . . . . . . . . . . . 18
7. PCEP Object Extensions . . . . . . . . . . . . . . . . . . . 19
7.1. Extension of LSP Object . . . . . . . . . . . . . . . . . 19
7.1.1. P2MP-LSP-IDENTIFIERS TLV . . . . . . . . . . . . . . 19
7.2. S2LS Object . . . . . . . . . . . . . . . . . . . . . . . 22
8. Message Fragmentation . . . . . . . . . . . . . . . . . . . . 23
8.1. Report Fragmentation Procedure . . . . . . . . . . . . . 23
8.2. Update Fragmentation Procedure . . . . . . . . . . . . . 24
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8.3. PCIntiate Fragmentation Procedure . . . . . . . . . . . . 24
9. Non-Support of P2MP TE LSPs for Stateful PCE . . . . . . . . 24
10. Manageability Considerations . . . . . . . . . . . . . . . . 25
10.1. Control of Function and Policy . . . . . . . . . . . . . 25
10.2. Information and Data Models . . . . . . . . . . . . . . 25
10.3. Liveness Detection and Monitoring . . . . . . . . . . . 26
10.4. Verify Correct Operations . . . . . . . . . . . . . . . 26
10.5. Requirements On Other Protocols . . . . . . . . . . . . 26
10.6. Impact On Network Operations . . . . . . . . . . . . . . 26
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
11.1. PCE Capabilities in IGP Advertisements . . . . . . . . . 26
11.2. STATEFUL-PCE-CAPABILITY TLV . . . . . . . . . . . . . . 27
11.3. LSP Object . . . . . . . . . . . . . . . . . . . . . . . 27
11.4. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 28
11.5. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 29
11.6. PCEP object . . . . . . . . . . . . . . . . . . . . . . 29
11.7. S2LS object . . . . . . . . . . . . . . . . . . . . . . 29
12. Security Considerations . . . . . . . . . . . . . . . . . . . 30
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 31
14.1. Normative References . . . . . . . . . . . . . . . . . . 31
14.2. Informative References . . . . . . . . . . . . . . . . . 33
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
1. Introduction
As per [RFC4655], the Path Computation Element (PCE) is an entity
that is capable of computing a network path or route based on a
network graph and applying computational constraints. A Path
Computation Client (PCC) may make requests to a PCE for paths to be
computed.
[RFC4875] describes how to set up point-to-multipoint (P2MP) Traffic
Engineering Label Switched Paths (TE LSPs) for use in Multiprotocol
Label Switching (MPLS) and Generalized MPLS (GMPLS) networks.
[RFC5671] examines the applicability of PCE for the path computation
for P2MP TE LSPs.
The PCEP is designed as a communication protocol between PCCs and
PCEs for point-to-point (P2P) path computations and is defined in
[RFC5440]. The extensions of PCEP to request path computation for
P2MP TE LSPs are described in [RFC8306].
Stateful PCEs are shown to be helpful in many application scenarios,
in both MPLS and GMPLS networks, as illustrated in [RFC8051]. These
scenarios apply equally to P2P and P2MP TE LSPs. [RFC8231] provides
the fundamental extensions to PCEP needed for stateful PCE to support
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general functionality for P2P TE LSP. [RFC8281] provides extensions
to PCEP needed for stateful PCE-initiated P2P TE LSP. This document
complements that work by focusing on PCEP extensions that are
necessary in order for the deployment of stateful PCEs to support
P2MP TE LSPs. This document describes the setup, maintenance, and
teardown of PCE-initiated P2MP LSPs under the stateful PCE model.
1.1. 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.
2. Terminology
Terminology used in this document is the same as terminology used in
[RFC8231], [RFC8281], and [RFC8306].
3. Supporting P2MP TE LSPs for Stateful PCE
3.1. Motivation
[RFC8051] presents several use cases, demonstrating scenarios that
benefit from the deployment of a stateful PCE including optimization,
recovery, etc., which are equally applicable to P2MP TE LSPs.
[RFC8231] defines the extensions to PCEP needed for stateful
operation of P2P TE LSPs. This document complements the previous
work by focusing on extensions that are necessary in order for the
deployment of stateful PCEs to support P2MP TE LSPs.
In addition to that, the stateful nature of a PCE simplifies the
information conveyed in PCEP messages since it is possible to refer
to the LSPs via a PCEP-specific LSP identifier (PLSP-ID) ([RFC8231]).
For P2MP, where the size of message is much larger, this is an added
advantage. When using a stateless PCE, a request to modify an
existing P2MP tree requires that all the leaves are presented in the
PCEP messages along with all the path information. But when using a
stateful PCE, the PCEP messages can use a PLSP-ID to represent all
information about the LSP that has previously been exchanged in PCEP
messages, and it is only necessary to encode the modifications (such
as new or removed leaf nodes). The PLSP-ID provides an index into
the LSP-DB at the PCE, and identifies the LSP at the PCC.
In environments where the P2MP TE LSPs placement needs to change in
response to application demands, it is useful to support dynamic
creation and tear down of P2MP TE LSPs. The ability for a PCE to
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trigger the creation of P2MP TE LSPs on demand can be seamlessly
integrated into a controller-based network architecture, where
intelligence in the controller can determine when and where to set up
paths. Section 3 of [RFC8281] further describes the motivation
behind the PCE-Initiation capability, which is equally applicable to
P2MP TE LSPs.
3.2. Objectives
The objectives for the protocol extensions to support P2MP TE LSPs
for stateful PCE are same as the objectives described in section 3.2
of [RFC8231].
4. Functions to Support P2MP TE LSPs for Stateful PCEs
[RFC8231] specifies new functions to support a stateful PCE. It also
specifies that a function can be initiated either from a PCC towards
a PCE (C-E) or from a PCE towards a PCC (E-C).
This document extends these functions to support P2MP TE LSPs.
Capability Advertisement (E-C,C-E): both the PCC and the PCE must
announce during PCEP session establishment that they support
Stateful PCE extensions for P2MP using mechanisms defined in
Section 5.2.
LSP State Synchronization (C-E): after the session between the PCC
and a stateful PCE with P2MP capability is initialized, the PCE
must learn the state of a PCC's P2MP TE LSPs before it can perform
path computations or update LSP attributes in a PCC.
LSP Update Request (E-C): a stateful PCE with P2MP capability
requests modification of attributes on a PCC's P2MP TE LSPs.
LSP State Report (C-E): a PCC sends an LSP state report to a PCE
whenever the state of a P2MP TE LSP changes.
LSP Control Delegation (C-E,E-C): a PCC grants to a PCE the right to
update LSP attributes on one or more P2MP TE LSPs; the PCE becomes
the authoritative source of the LSP's attributes as long as the
delegation is in effect (See Section 5.7 of [RFC8231]); the PCC
may withdraw the delegation or the PCE may give up the delegation
at any time.
PCE-initiated LSP instantiation (E-C): a PCE sends an LSP Initiate
Message to a PCC to instantiate or delete a P2MP TE LSP [RFC8281].
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5. Architectural Overview of Protocol Extensions
5.1. Extension of PCEP Messages
New PCEP messages are defined in [RFC8231] to support stateful PCE
for P2P TE LSPs. In this document these messages are extended to
support P2MP TE LSPs.
Path Computation State Report (PCRpt): Each P2MP TE LSP State Report
in a PCRpt message contains the actual P2MP TE LSP path
attributes, the LSP status, etc. An LSP State Report carried in a
PCRpt message is also used in delegation or revocation of control
of a P2MP TE LSP to/from a PCE. The extension of PCRpt message is
described in Section 6.1.
Path Computation Update Request (PCUpd): Each P2MP TE LSP Update
Request in a PCUpd message MUST contain all LSP parameters that a
PCE wishes to set for a given P2MP TE LSP. An LSP Update Request
carried in a PCUpd message is also used to return LSP delegations
if at any point PCE no longer desires control of a P2MP TE LSP.
The PCUpd message is described in Section 6.2.
A PCEP message is defined in [RFC8281] to support stateful PCE
instantiation of P2P TE LSPs. In this document this message is
extended to support P2MP TE LSPs.
Path Computation LSP Initiate Message (PCInitiate): PCInitiate is a
PCEP message sent by a PCE to a PCC to trigger P2MP TE LSPs
instantiation or deletion. The PCInitiate message is described in
Section 6.5.
The Path Computation Request (PCReq) and Path Computation Reply
(PCRep) messages are also extended to support passive stateful PCE
for P2P TE LSP in [RFC8231]. In this document these messages are
extended to support P2MP TE LSPs as well.
5.2. Capability Advertisement
During PCEP Initialization Phase, as per Section 7.1.1 of [RFC8231],
PCEP speakers advertise Stateful capability via the STATEFUL-PCE-
CAPABILITY TLV in the OPEN object. Various flags are defined for the
STATEFUL-PCE-CAPABILITY TLV defined in [RFC8231] and updated in
[RFC8281] and [RFC8232].
Three new flags N (P2MP-CAPABILITY), M (P2MP-LSP-UPDATE-CAPABILITY),
and P (P2MP-LSP-INSTANTIATION-CAPABILITY) are added in this document:
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N (P2MP-CAPABILITY flag - 1 bit): if set to 1 by a PCC, the N Flag
indicates that the PCC is willing to send P2MP LSP State Reports
whenever any parameters or operational status change of the P2MP
LSP; if set to 1 by a PCE, the N Flag indicates that the PCE is
interested in receiving LSP State Reports whenever there is any
parameters or operational status change of the P2MP LSP. The
P2MP-CAPABILITY Flag MUST be advertised by both a PCC and a PCE
for PCRpt messages P2MP extension to be allowed on a PCEP session.
M (P2MP-LSP-UPDATE-CAPABILITY flag - 1 bit): if set to 1 by a PCC,
the M Flag indicates that the PCC allows modification of P2MP LSP
parameters; if set to 1 by a PCE, the M Flag indicates that the
PCE is capable of updating P2MP LSP parameters. The P2MP-LSP-
UPDATE-CAPABILITY Flag MUST be advertised by both a PCC and a PCE
for PCUpd messages P2MP extension to be allowed on a PCEP session.
P (P2MP-LSP-INSTANTIATION-CAPABILITY flag - 1 bit): If set to 1 by a
PCC, the P Flag indicates that the PCC allows instantiation of a
P2MP LSP by a PCE. If set to 1 by a PCE, the P flag indicates
that the PCE supports P2MP LSP instantiation. The P2MP-LSP-
INSTANTIATION-CAPABILITY flag MUST be set by both PCC and PCE in
order to support PCE-initiated P2MP LSP instantiation.
A PCEP speaker should continue to advertise the basic P2MP capability
via mechanisms as described in [RFC8306].
5.3. IGP Extensions for Stateful PCE P2MP Capabilities Advertisement
When PCC is a Label Switching Router (LSR), participating in the IGP
(OSPF or IS-IS), and PCEs are either LSRs or servers also
participating in the IGP, an effective mechanism for PCE discovery
within an IGP routing domain consists of utilizing IGP
advertisements. Extensions for the advertisement of PCE Discovery
Information are defined for OSPF and for IS-IS in [RFC5088] and
[RFC5089] respectively.
The PCE-CAP-FLAGS sub-TLV, defined in [RFC5089], is an optional sub-
TLV used to advertise PCE capabilities. It MAY be present within the
PCE Discovery (PCED) TLV carried by OSPF or IS-IS. [RFC5088] and
[RFC5089] provide the description and processing rules for this sub-
TLV when carried within OSPF and IS-IS, respectively.
The format of the PCE-CAP-FLAGS sub-TLV is included below for easy
reference:
Type: 5
Length: Multiple of 4.
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Value: This contains an array of units of 32 bit flags with the most
significant bit as 0. Each bit represents one PCE capability.
PCE capability bit flags are defined in [RFC5088]. This document
defines new capability bits (early allocated by IANA) for the
stateful PCE with P2MP as follows:
Bit Capability
13 Active Stateful PCE with P2MP
14 Passive Stateful PCE with P2MP
15 PCE-Initiation with P2MP
Note that while active, passive or initiation stateful PCE with P2MP
capabilities may be advertised during discovery, PCEP Speakers that
wish to use stateful PCEP MUST advertise stateful PCEP capabilities
during PCEP session setup, as specified in the current document. A
PCC MAY initiate stateful PCEP P2MP capability advertisement at PCEP
session setup even if it did not receive any IGP PCE capability
advertisements.
5.4. State Synchronization
State Synchronization operations (described in Section 5.6 of
[RFC8231]) are applicable for the P2MP TE LSPs as well. The
optimizations described in [RFC8232] can also be applied for P2MP TE
LSPs.
5.5. LSP Delegation
LSP delegation operations (described in Section 5.7 of [RFC8231]) are
applicable for P2MP TE LSPs as well.
5.6. LSP Operations
5.6.1. Passive Stateful PCE
LSP operations for passive stateful PCE (described in Section 5.8.1
of [RFC8231]) are applicable for P2MP TE LSPs as well.
The PCReq and PCRep message format for P2MP TE LSPs is described in
Section 3.4 and Section 3.5 of [RFC8306] respectively.
The PCReq and PCRep message for P2MP TE LSPs are extended to support
encoding of LSP object, so that it is possible to refer to an LSP
with a unique identifier and simplify the PCEP message exchange. For
example, in case of modification of one leaf in a P2MP tree, there
should be no need to carry the full P2MP tree in PCReq message.
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The extension for the Request and Response message for passive
stateful operations on P2MP TE LSPs are described in Section 6.3 and
Section 6.4. The extension for the Path Computation LSP State Report
(PCRpt) message is described in Section 6.1.
5.6.2. Active Stateful PCE
LSP operations for active stateful PCE (described in Section 5.8.2 of
[RFC8231]) are applicable for P2MP TE LSPs as well.
The extension for the Path Computation LSP Update (PCUpd) message for
active stateful operations on P2MP TE LSPs are described in
Section 6.2.
5.6.3. PCE-Initiated LSP
As per section 5.1 of [RFC8281], the PCE sends a Path Computation LSP
Initiate Request (PCInitiate) message to the PCC to suggest
instantiation or deletion of a P2P TE LSP. This document extends the
PCInitiate message to support P2MP TE LSPs (see details in
Section 6.5).
The P2MP TE LSPs suggested instantiation and deletion operations are
same as for P2P LSP as described in section 5.3 and 5.4 of [RFC8281].
5.6.3.1. P2MP TE LSPs Instantiation
The Instantiation operation of P2MP TE LSPs is the same as defined in
section 5.3 of [RFC8281], including handling of PLSP-ID, SYMBOLIC-
PATH-NAME TLV, etc. The rules for processing and use of error codes
remains unchanged. The N (P2MP) flag (Section 7.1) MUST be set in
the LSP object in PCInitiate message by the PCE to specify that the
instantiation is for P2MP TE LSPs. Like the PLSP-ID (as per
[RFC8281]), the P2MP-LSP-IDENTIFIERS TLV SHOULD NOT be included in
the LSP object in PCIntiitate messages and MUST be ignored on
receipt. These identifiers are generated by the PCC on receipt of
PCIntiitate message and reported via PCRpt message to the PCE.
5.6.3.2. P2MP TE LSPs Deletion
The deletion operation of P2MP TE LSPs is the same as defined in
section 5.4 of [RFC8281] by sending an LSP Initiate Message with an
LSP object carrying the PLSP-ID of the LSP to be removed and an SRP
object with the R flag set (LSP-REMOVE as per section 5.2 of
[RFC8281]). Rules of processing and error codes remains unchanged.
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5.6.3.3. Adding and Pruning Leaves for the P2MP TE LSP
Adding of new leaves and Pruning of old Leaves for the PCE initiated
P2MP TE LSP MUST be carried in PCUpd message as per Section 6.2 for
P2MP TE LSP extensions. As defined in [RFC8306], leaf type = 1 for
adding of new leaves, leaf type = 2 for pruning of old leaves of P2MP
END-POINTS Object are used in PCUpd message.
PCC MAY use the Incremental State Update mechanism as described in
[RFC4875] to signal adding and pruning of leaves.
Section 3.10 of [RFC8306] defines the error-handling procedures when
adding new leaves to or removing old leaves from the existing P2MP
tree for PCReq message. The same error handling and error-codes are
also applicable to the stateful PCE messages as described in this
document.
5.6.3.4. P2MP TE LSPs Delegation and Cleanup
P2MP TE LSPs delegation and cleanup operations are same as defined in
section 6 of [RFC8281]. Rules of processing and error codes remains
unchanged.
6. PCEP Message Extensions
Message formats in this section, as those in [RFC8231], [RFC8281],
and [RFC5440], are presented using Routing Backus-Naur Format (RBNF)
as specified in [RFC5511].
6.1. The PCRpt Message
As per Section 6.1 of [RFC8231], PCRpt message is used to report the
current state of a P2P TE LSP. This document extends the PCRpt
message in reporting the status of P2MP TE LSPs.
The format of PCRpt message is as follows:
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<PCRpt Message> ::= <Common Header>
<state-report-list>
Where:
<state-report-list> ::= <state-report>
[<state-report-list>]
<state-report> ::= [<SRP>]
<LSP>
<path>
Where:
<path> ::= <end-point-intended-path-pair-list>
[<actual-attribute-list>
<end-point-actual-path-pair-list>]
[<intended-attribute-list>]
<end-point-intended-path-pair-list>::=
[<END-POINTS>]
[<S2LS>]
<intended-path>
[<end-point-intended-path-pair-list>]
<end-point-actual-path-pair-list>::=
[<END-POINTS>]
[<S2LS>]
<actual-path>
[<end-point-actual-path-pair-list>]
<intended-path> ::= (<ERO>|<SERO>)
[<intended-path>]
<actual-path> ::= (<RRO>|<SRRO>)
[<actual-path>]
<intended-attribute-list> is defined in [RFC5440] and
extended by PCEP extensions.
<actual-attribute-list> consists of the actual computed and
signaled values of the <BANDWIDTH> and <metric-lists>
objects defined in [RFC5440].
The P2MP END-POINTS object defined in [RFC8306] is mandatory for
specifying address of P2MP leaves, grouped by leaf types.
o New leaves to add (leaf type = 1)
o Old leaves to remove (leaf type = 2)
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o Old leaves whose path can be modified/reoptimized (leaf type = 3)
o Old leaves whose path must be left unchanged (leaf type = 4)
When reporting the status of a P2MP TE LSP, the destinations MUST be
grouped in END-POINTS object based on the operational status (O field
in S2LS object) and leaf type (in END-POINTS). This way, leaves of
the same type that share the same operational status can be grouped
together. For reporting the status of delegated P2MP TE LSPs leaf
type = 3 is used, whereas for non-delegated P2MP TE LSPs, leaf type =
4 is used.
For a delegated P2MP TE LSP configuration changes are reported via
PCRpt message. For example, adding of new leaves END-POINTS (leaf
type = 1) is used, and removing of old leaves (leaf type = 2) is
used.
Note that the compatibility with the [RFC8231] definition of <state-
report> is preserved. At least one instance of <END-POINTS> MUST be
present in this message for P2MP LSP.
Note that the ordering of <end-point-intended-path-pair-list>,
<actual-attribute-list>, <end-point-actual-path-pair-list>, and
<intended-attribute-list> is done to retain compatibility with state
reports for the P2P LSPs as per [RFC8231].
During state synchronization, the PCRpt message reports the status of
the full P2MP tree.
The S2LS object MUST be carried in PCRpt message along with END-
POINTS object when N (P2MP) flag is set in LSP object for P2MP TE
LSPs. If the S2LS object is missing, the receiving PCE MUST send a
PCErr message with Error-type=6 ("Mandatory Object missing") and
Error-value=13 (early allocated by IANA) ("S2LS object missing"). If
the END-POINTS object is missing, the receiving PCE MUST send a PCErr
message with Error-type=6 ("Mandatory Object missing") and Error-
value=3 ("END-POINTS object missing") (defined in [RFC5440].
The S2LS object could be used in conjunction with the intended-path
(ERO) as well as the actual-path (RRO); for the same leaf, the state
encoded in the S2LS object associated with the actual-path MUST be
used over the intended-path.
If the E-bit (ERO-Compress bit) was set to 1 in the report, then the
path will be formed by an ERO followed by a list of SEROs or RRO
followed by a list of SRROs.
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6.2. The PCUpd Message
As per Section 6.2 of [RFC8231], PCUpd message is used to update P2P
TE LSP attributes. This document extends the PCUpd message in
updating the attributes of a P2MP TE LSP.
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>
<path>
Where:
<path> ::= <end-point-path-pair-list>
<intended-attribute-list>
<end-point-path-pair-list>::=
[<END-POINTS>]
<intended-path>
[<end-point-path-pair-list>]
<intended-path> ::= (<ERO>|<SERO>)
[<intended-path>]
<intended-attribute-list> is the attribute-list
defined in [RFC5440] and extended by PCEP extensions.
Note that the compatibility with the [RFC8231] definition of <update-
request> is preserved.
The PCC SHOULD use the make-before-break or sub-group-based
procedures described in [RFC4875] based on a local policy decision.
The END-POINTS object MUST be carried in PCUpd message when N flag is
set in LSP object for a P2MP TE LSP. If the END-POINTS object is
missing, the receiving PCC MUST send a PCErr message with Error-
type=6 ("Mandatory Object missing") and Error-value=3 ("END-POINTS
object missing") (defined in [RFC5440]).
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6.3. The PCReq Message
As per Section 3.4 of [RFC8306], PCReq message is used for a P2MP
Path Computation Request. This document extends the PCReq message
such that a PCC MAY include the LSP object in the PCReq message if
the stateful PCE P2MP capability has been negotiated on a PCEP
session between the PCC and a PCE.
The format of PCReq message is as follows:
<PCReq Message>::= <Common Header>
[<svec-list>]
<request-list>
where:
<svec-list>::= <SVEC>
[<OF>]
[<metric-list>]
[<svec-list>]
<request-list>::=<request>[<request-list>]
<request>::= <RP>
<end-point-rro-pair-list>
[<LSP>]
[<OF>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>|<BNC>]
[<LOAD-BALANCING>]
<end-point-rro-pair-list>::= <END-POINTS>
[<RRO-List>[<BANDWIDTH>]]
[<end-point-rro-pair-list>]
<RRO-List>::=(<RRO>|<SRRO>)[<RRO-List>]
<metric-list>::=<METRIC>[<metric-list>]
6.4. The PCRep Message
As per Section 3.5 of [RFC8306], PCRep message is used for a P2MP
Path Computation Reply. This document extends the PCRep message such
that a PCE MAY include the LSP object in the PCRep message if the
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stateful PCE P2MP capability has been negotiated on a PCEP session
between the PCC and a PCE.
The format of PCRep message is as follows:
<PCRep Message>::= <Common Header>
<response-list>
where:
<response-list>::=<response>[<response-list>]
<response>::=<RP>
[<end-point-path-pair-list>]
[<LSP>]
[<NO-PATH>]
[<UNREACH-DESTINATION>]
[<attribute-list>]
<end-point-path-pair-list>::= [<END-POINTS>]
<path>
[<end-point-path-pair-list>]
<path> ::= (<ERO>|<SERO>) [<path>]
<attribute-list>::=[<OF>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>]
6.5. The PCInitiate message
As defined in section 5.1 of [RFC8281], PCE sends a PCInitiate
message to a PCC to recommend instantiation of a P2P TE LSP. This
document extends the format of PCInitiate message for the creation of
P2MP TE LSPs but the creation and deletion operations of P2MP TE LSPs
are same to the P2P TE LSPs.
The format of PCInitiate message is as follows:
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<PCInitiate Message> ::= <Common Header>
<PCE-initiated-lsp-list>
Where:
<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-point-path-pair-list>
[<attribute-list>]
<PCE-initiated-lsp-deletion> ::= <SRP>
<LSP>
Where:
<end-point-path-pair-list>::=
[<END-POINTS>]
<intended-path>
[<end-point-path-pair-list>]
<intended-path> ::= (<ERO>|<SERO>)
[<intended-path>]
<attribute-list> is defined in [RFC5440] and extended
by PCEP extensions.
The PCInitiate message with an LSP object with N flag (P2MP) set is
used to convey operation on a P2MP TE LSP. The SRP object is used to
correlate between initiation requests sent by the PCE and the error
reports and state reports sent by the PCC as described in [RFC8231].
The END-POINTS object MUST be carried in PCInitiate message when N
flag is set in LSP object for a P2MP TE LSP. If the END-POINTS
object is missing, the receiving PCC MUST send a PCErr message with
Error-type=6 ("Mandatory Object missing") and Error-value=3 ("END-
POINTS object missing") (defined in [RFC5440]).
6.6. Example
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6.6.1. P2MP TE LSPs Update Request
An LSP Update Request message is sent by an active stateful PCE to
update the P2MP TE LSPs parameters or attributes. An example of a
PCUpd message for P2MP TE LSPs is described below:
Common Header
SRP
LSP with P2MP flag set
END-POINTS for leaf type 3
ERO list
In this example, a stateful PCE requests an update of the path taken
to some of the leaves in a P2MP tree. The update request uses the
END-POINT type 3 (modified/reoptimized). The ERO list represents the
source to leaves path after modification. The update message does
not need to encode the full P2MP tree in this case.
6.6.2. P2MP TE LSP Report
The LSP State Report message is sent by a PCC to report or delegate
the P2MP TE LSP. The leaves of the P2MP TE LSP are grouped in the
END-POINTS object based on the operational status and the leaf type.
An example of a PCRpt message for a delegated P2MP TE LSPs is
described below to add new leaves to an existing P2MP TE LSP:
Common Header
LSP with P2MP flag set
END-POINTS for leaf type 1 (add)
S2LS (O=DOWN)
ERO list (empty)
An example of a PCRpt message for a P2MP TE LSP is described below to
prune leaves from an existing P2MP TE LSP:
Common Header
LSP with P2MP flag set
END-POINTS for leaf type 2 (remove)
S2LS (O=UP)
ERO list (empty)
An example of a PCRpt message for a delegated P2MP TE LSP is
described below to report status of leaves in an existing P2MP TE
LSP:
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Common Header
SRP
LSP with P2MP flag set
END-POINTS for leaf type 3 (modify)
S2LS (O=UP)
RRO list
END-POINTS for leaf type 3 (modify)
S2LS (O=DOWN)
ERO list (empty)
In this example, the PCRpt message is in response to a PCUpd message
(with corresponding SRP) object indicating some leaves that are up
(with the actual path) and some are down.
An example of a PCRpt message for a non-delegated P2MP TE LSP is
described below to report status of leaves:
Common Header
LSP with P2MP flag set
END-POINTS for leaf type 4 (unchanged)
S2LS (O=ACTIVE)
RRO list
END-POINTS for leaf type 4 (unchanged)
S2LS (O=DOWN)
ERO list (empty)
6.6.3. P2MP TE LSPs Initiation Request
An LSP Initiation Request message is sent by an stateful PCE to
create a P2MP TE LSP. An example of a PCInitiate message for a P2MP
TE LSP is described below:
Common Header
SRP
LSP with P2MP flag set
END-POINTS for leaf type 1 (add)
ERO list
In this example, a stateful PCE request creation of a P2MP TE LSP.
The initiation request uses the END-POINT type 1 (new leaves). The
ERO list represents the source to leaves path. The initiate message
encodes the full P2MP tree in this case.
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7. PCEP Object Extensions
The new PCEP TLVs defined in this document are in compliance with the
PCEP TLV format defined in [RFC5440].
7.1. Extension of LSP Object
The LSP Object is defined in Section 7.3 of [RFC8231]. It specifies
the PLSP-ID to uniquely identify an LSP that is constant for the life
time of a PCEP session. Similarly for a P2MP tunnel, the PLSP-ID
identify a P2MP TE LSP uniquely. This document adds the following
flags to the LSP Object:
N (P2MP flag - 1 bit): If the N flag is set to 1, it indicates that
the message is for a P2MP TE LSP.
F (Fragmentation flag - 1 bit): If the F flag is unset (0), it
indicates that the LSP is not fragmented or it is the last piece
of the fragmented LSP. If the F flag is set to 1, it indicates
that the LSP is fragmented and this is not the last piece of the
fragmented LSP. The receiver needs to wait for additional
fragments until it receives an LSP with the same PLSP-ID and with
the F-bit set to 0. See Section 8 for further details.
E (ERO-compression flag - 1 bit): If the E flag is set to 1, it
indicates the route is in compressed format (that is, Secondary
Explicit Route Object (SERO) and Secondary Record Route Object
(SRRO) objects [RFC8306] are in use).
The flags defined in this section (N, F, E flags) are used in PCRpt,
PCUpd, or PCInitiate message. In case of PCReq and PCRep message,
these flags have no meaning and thus MUST be ignored. The
corresponding flags in the RP (Request Parameters) object are used as
described in [RFC8306].
7.1.1. P2MP-LSP-IDENTIFIERS TLV
[RFC8231] specify the LSP-IDENTIFIERS TLVs to be included in the LSP
object. For P2MP TE LSP, this document defines P2MP-LSP-IDENTIFIERS
TLVs for the LSP object. There are two P2MP-LSP-IDENTIFIERS TLVs,
one for IPv4 and one for IPv6. The P2MP-LSP-IDENTIFIERS TLV MUST be
included in the LSP object in PCRpt message for P2MP TE LSPs. If the
N bit is set in the LSP object in the PCRpt message but the P2MP-LSP-
IDENTIFIER TLV is absent, the PCE MUST respond with a PCErr message
carrying error-type 6 ("mandatory object missing") and error-value 14
(early allocated by IANA) ("P2MP-LSP-IDENTIFIER TLV missing") and
close the PCEP session.
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The P2MP-LSP-IDENTIFIERS TLV MAY be included in the LSP object in the
PCUpd message for P2MP TE LSPs. The special value of all zeros for
all the fields in the value portion of the TLV is used to refer to
all paths pertaining to a particular PLSP-ID. The length of the TLV
remains fixed based on the IP version.
The P2MP-LSP-IDENTIFIERS TLV SHOULD NOT be used in PCInitiate (see
Section 5.6.3.1) and MAY optionally be included in the LSP object in
the PCReq and the PCRep message for P2MP TE LSP.
The format of the IPV4-P2MP-LSP-IDENTIFIERS TLV is shown in the
Figure 6:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=32 | Length=16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Tunnel Sender Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP ID | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| P2MP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: IPV4-P2MP-LSP-IDENTIFIERS TLV format
The type (16-bits) of the TLV is 32 (early allocated by IANA). The
length (16-bits) has a fixed value of 16 octets. The value contains
the following fields:
IPv4 Tunnel Sender Address: contains the sender node's IPv4 address,
as defined in [RFC3209], Section 4.6.2.1 for the LSP_TUNNEL_IPv4
Sender Template Object.
LSP ID: contains the 16-bits 'LSP ID' identifier defined in
[RFC3209], Section 4.6.2.1 for the LSP_TUNNEL_IPv4 Sender Template
Object.
Tunnel ID: contains the 16-bits 'Tunnel ID' identifier defined in
[RFC3209], Section 4.6.1.1 for the LSP_TUNNEL_IPv4 Session Object.
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Extended Tunnel ID: contains the 32-bits 'Extended Tunnel ID'
identifier defined in [RFC3209], Section 4.6.1.1 for the
LSP_TUNNEL_IPv4 Session Object.
P2MP ID: contains the 32-bits 'P2MP ID' identifier defined in
Section 19.1.1 of [RFC4875] for the P2MP LSP Tunnel IPv4 SESSION
Object.
The format of the IPV6-P2MP-LSP-IDENTIFIERS TLV is shown in the
Figure 7:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=33 | Length=40 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| IPv6 tunnel sender address |
+ (16 octets) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP ID | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| Extended Tunnel ID |
+ (16 octets) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| P2MP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: IPV6-P2MP-LSP-IDENTIFIERS TLV format
The type (16-bits) of the TLV is 33 (early allocated by IANA). The
length (16-bits) has a fixed length of 40 octets. The value contains
the following fields:
IPv6 Tunnel Sender Address: contains the sender node's IPv6 address,
as defined in [RFC3209], Section 4.6.2.2 for the LSP_TUNNEL_IPv6
Sender Template Object.
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LSP ID: contains the 16-bits 'LSP ID' identifier defined in
[RFC3209], Section 4.6.2.2 for the LSP_TUNNEL_IPv6 Sender Template
Object.
Tunnel ID: contains the 16-bits 'Tunnel ID' identifier defined in
[RFC3209], Section 4.6.1.2 for the LSP_TUNNEL_IPv6 Session Object.
Extended Tunnel ID: contains the 128-bits 'Extended Tunnel ID'
identifier defined in [RFC3209], Section 4.6.1.2 for the
LSP_TUNNEL_IPv6 Session Object.
P2MP ID: As defined above in IPV4-P2MP-LSP-IDENTIFIERS TLV.
Tunnel ID remains constant over the life time of a tunnel.
7.2. S2LS Object
The S2LS (Source-to-Leaves) Object is used to report state of one or
more destinations (leaves) encoded within the END-POINTS object for a
P2MP TE LSP. It MUST be carried in PCRpt message along with END-
POINTS object when N flag is set in LSP object.
S2LS Object-Class is 41 (Early allocated by IANA).
S2LS Object-Types is 1.
The format of the S2LS object is shown in the following figure:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | O|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Optional TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: S2LS object format
Flags(32-bits): the following flags are currently defined -
O(Operational - 3 bits) the O Field represents the operational
status of the group of destinations. The values are as per
Operational field in LSP object defined in Section 7.3 of
[RFC8231].
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Unassigned bits are reserved for future uses. They MUST be set to 0
on transmission and MUST be ignored on receipt.
When N flag is set in LSP object then the O field in LSP object
represents the operational status of the full P2MP TE LSP and the O
field in S2LS object represents the operational status of a group of
destinations encoded within the END-POINTS object. If there is a
conflict between the O field in the LSP and the S2LS object (for
example, O field in LSP corresponds to down whereas the O field in
S2LS is up), the PCEP speaker MUST generate an error with error-type
10 ("Reception of an invalid object") and error-value TBD1 (to be
allocated by IANA) ("Mis-match of O field in S2LS and LSP object").
Future documents might define optional TLVs that could be included in
the S2LS Object.
8. Message Fragmentation
The total PCEP message length, including the common header, is
(2^16)-1 bytes. In certain scenarios the P2MP report and update
request may not fit into a single PCEP message (e.g. initial report
or update). The F flag is used in the LSP object to signal that the
initial report, update, or initiate message was too large to fit into
a single message and will be fragmented into multiple messages. In
order to identify the single report or update each message will use
the same PLSP-ID. In order to identify that a series of PCInitiate
messages represents a single Initiate, each message will use the same
PLSP-ID (in this case 0) and SRP-ID-number.
The fragmentation procedure described below for report or update
message is similar to [RFC8306] which describes request and response
message fragmentation.
8.1. Report Fragmentation Procedure
If the initial report is too large to fit into a single report
message, the PCC will split the report over multiple messages. Each
message sent to the PCE, except the last one, will have the F flag
set in the LSP object to signify that the report has been fragmented
into multiple messages. In order to identify that a series of report
messages represents a single report, each message will use the same
PLSP-ID.
The Error-Type value 18 ("P2MP Fragmentation Error") is used to
report any error associated with the fragmentation of a P2MP PCEP
message. A new error-value 2 (early allocated by IANA) indicates
"Fragmented report failure" and is used if a PCE does not receive the
last part of the fragmented message.
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8.2. Update Fragmentation Procedure
Once the PCE computes and updates a path for some or all leaves in a
P2MP TE LSP, an update message is sent to the PCC. If the update is
too large to fit into a single update message, the PCE will split the
update over multiple messages. Each update message sent by the PCE,
except the last one, will have the F flag set in the LSP object to
signify that the update has been fragmented into multiple messages.
In order to identify that a series of update messages represents a
single update, each message will use the same PLSP-ID and SRP-ID-
number.
The Error-Type value 18 ("P2MP Fragmentation Error") is used to
report any error associated with the fragmentation of a P2MP PCEP
message. A new error-value 3 (early allocated by IANA) indicates
"Fragmented update failure" and is used if a PCC does not receive the
last part of the fragmented message.
8.3. PCIntiate Fragmentation Procedure
Once the PCE initiates to set up a P2MP TE LSP, a PCInitiate message
is sent to the PCC. If the PCInitiate is too large to fit into a
single PCInitiate message, the PCE will split the PCInitiate over
multiple messages. Each PCInitiate message sent by the PCE, except
the last one, will have the F flag set in the LSP object to signify
that the PCInitiate has been fragmented into multiple messages. In
order to identify that a series of PCInitiate messages represents a
single Initiate, each message will use the same PLSP-ID (in this case
0) and SRP-ID-number.
The Error-Type value 18 ("P2MP Fragmentation Error") is used to
report any error associated with the fragmentation of a P2MP PCEP
message. A new error-value 4 (early allocated by IANA) indicates
"Fragmented instantiation failure" and is used if a PCC does not
receive the last part of the fragmented message.
9. Non-Support of P2MP TE LSPs for Stateful PCE
The PCEP extensions described in this document for stateful PCEs with
P2MP capability MUST NOT be used if PCE has not advertised its
stateful capability with P2MP as per Section 5.2. If the PCC
supports the extensions as per this document (understands the N
(P2MP-CAPABILITY) and M (P2MP-LSP-UPDATE-CAPABILITY) flags in the LSP
object) but did not advertise this capability, then upon receipt of
PCUpd message from the PCE, it SHOULD generate a PCErr with error-
type 19 ("Invalid Operation"), error-value 12 (early allocated by
IANA) ("Attempted LSP Update Request for P2MP if active stateful PCE
capability for P2MP was not advertised") and terminate the PCEP
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session. If the PCE supports the extensions as per this document
(understands the N (P2MP-CAPABILITY) flag in the LSP object) but did
not advertise this capability, then upon receipt of a PCRpt message
from the PCC, it SHOULD generate a PCErr with error-type 19 ("Invalid
Operation"), error-value 11 (early allocated by IANA) ("Attempted LSP
State Report for P2MP if stateful PCE capability for P2MP was not
advertised") and it SHOULD terminate the PCEP session.
If a Stateful PCE receives a P2MP TE LSP report message and the PCE
does not understand the N (P2MP-CAPABILITY) flag in the LSP object,
and therefore the PCEP extensions described in this document, then
the Stateful PCE would act as per Section 6.1 of [RFC8231] (and
consider the PCRpt message as invalid).
The PCEP extensions described in this document for PCC or PCE with
instantiation capability for P2MP TE LSPs MUST NOT be used if PCC or
PCE has not advertised its stateful capability with Instantiation and
P2MP capability as per Section 5.2. If the PCC supports the
extensions as per this document (understands the P (P2MP-LSP-
INSTANTIATION-CAPABILITY) flag) but did not advertise this
capability, then upon receipt of PCInitiate message from the PCE, it
SHOULD generate a PCErr with error-type 19 ("Invalid Operation"),
error-value 13 (early allocated by IANA) ("Attempted LSP
Instantiation Request for P2MP if stateful PCE instantiation
capability for P2MP was not advertised") and terminate the PCEP
session..
10. Manageability Considerations
All manageability requirements and considerations listed in
[RFC5440], [RFC8306], [RFC8231], and [RFC8281] apply to PCEP
extensions defined in this document. In addition, requirements and
considerations listed in this section apply.
10.1. Control of Function and Policy
A PCE or PCC implementation MUST allow configuring the stateful PCEP
capability, the LSP Update capability, and the LSP Initiation
capability for P2MP LSPs.
10.2. Information and Data Models
The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to
include advertised P2MP stateful capabilities, P2MP synchronization
status, and delegation status of P2MP LSP etc. The statistics module
should also count P2MP LSP related data.
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10.3. 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].
10.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440], [RFC8306], [RFC8231], and [RFC8281].
10.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
10.6. Impact On Network Operations
Mechanisms defined in this document do not have any impact on network
operations in addition to those already listed in [RFC5440],
[RFC8306], [RFC8231], and [RFC8281].
Stateful PCE feature for P2MP LSP would help with network operations.
11. IANA Considerations
This document requests IANA to confirm the early allocation of the
code-points for the protocol elements defined in this document.
11.1. PCE Capabilities in IGP Advertisements
IANA is requested to confirm the early allocation for the new bits in
the OSPF Parameters "PCE Capability Flags" registry, as follows:
Bit Meaning Reference
13 Active Stateful [This.I-D]
PCE with P2MP
14 Passive Stateful [This.I-D]
PCE with P2MP
15 Stateful PCE [This.I-D]
Initiation with P2MP
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11.2. STATEFUL-PCE-CAPABILITY TLV
The STATEFUL-PCE-CAPABILITY TLV is defined in [RFC8231] and the
'STATEFUL-PCE-CAPABILITY TLV Flag Field' subregistry was created to
manage the flags in the TLV. IANA is requested to confirm the early
allocation of the following code-points in the aforementioned
registry.
Bit Description Reference
25 P2MP-CAPABILITY [This.I-D]
24 P2MP-LSP-UPDATE- [This.I-D]
CAPABILITY
23 P2MP-LSP- [This.I-D]
INSTANTIATION-
CAPABILITY
11.3. LSP Object
The LSP object is defined in [RFC8231] and the 'LSP Object Flag
Field' subregistry was created to manage the Flags field of the LSP
object.
IANA is requested to confirm the early allocation of the following
code-points in the aforementioned registry.
Bit Description Reference
3 P2MP [This.I-D]
2 Fragmentation [This.I-D]
Additionally, IANA is requested to allocate an additional code-point
in this registry.
Bit Description Reference
TBD ERO-compression [This.I-D]
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11.4. PCEP-Error Object
IANA is requested to confirm the early allocation of the new error
values within the "PCEP-ERROR Object Error Types and Values" sub-
registry of the PCEP Numbers registry, as follows:
Error-Type Meaning
6 Mandatory Object missing [RFC5440]
Error-value=13: S2LS object missing
Error-value=14: P2MP-LSP-IDENTIFIERS TLV missing
18 P2MP Fragmentation Error [RFC8306]
Error-value= 2. Fragmented Report
failure
Error-value= 3. Fragmented Update
failure
Error-value= 4. Fragmented Instantiation
failure
19 Invalid Operation [RFC8231]
Error-value= 11. Attempted LSP State Report
for P2MP if stateful PCE capability
for P2MP was not advertised
Error-value= 12. Attempted LSP Update Request
for P2MP if active stateful PCE capability
for P2MP was not advertised
Error-value= 13. Attempted LSP Instantiation
Request for P2MP if stateful PCE
instantiation capability for P2MP was not
advertised
Reference for all new Error-Value above is [This.I-D].
Additionally, IANA is requested to allocate an additional code-point
in this registry.
Error-Type Meaning
10 Reception of an invalid object [RFC5440]
Error-value=TBD1: Mis-match of O field in S2LS
and LSP object
Reference for all new Error-Value above is [This.I-D].
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11.5. PCEP TLV Type Indicators
IANA is requested to confirm the early allocation of the following
code-points in the existing "PCEP TLV Type Indicators" registry as
follows:
Value Meaning Reference
32 P2MP-IPV4-LSP-IDENTIFIERS [This.I-D]
33 P2MP-IPV6-LSP-IDENTIFIERS [This.I-D]
11.6. PCEP object
IANA is requested to confirm the early allocation for the new object-
class values and object types within the "PCEP Objects" sub-registry
of the PCEP Numbers registry, as follows.
Object-Class Value Name Reference
41 S2LS [This.I-D]
Object-Type
0: Reserved
1: S2LS
11.7. S2LS object
This document requests that a new sub-registry, named "S2LS Object
Flag Field", is created within the "Path Computation Element Protocol
(PCEP) Numbers" registry to manage the 32-bits Flag field of the S2LS
object. New values are to be assigned by Standards Action [RFC8126].
Each bit should be tracked with the following qualities:
o Bit number (counting from bit 0 as the most significant bit)
o Capability description
o Defining RFC
The following values are defined in this document:
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Bit Description Reference
29-31 Operational (3-bits) [This.I-D]
0-28 Unassigned
12. Security Considerations
The stateful operations on P2MP TE LSPs are more CPU-intensive and
also utilize more bandwidth on wire (in comparison to P2P TE LSPs).
If a rogue PCC were able to request unauthorized stateful PCE
operations then it may be able to mount a DoS attack against a PCE,
which would disrupt the network and deny service to other PCCs.
Similarly an attacker may flood the PCC with PCUpd messages at a rate
that exceeds either the PCC's ability to process them or the
network's ability to signal the changes, by either spoofing messages
or compromising the PCE itself.
Consequently, it is important that implementations conform to the
relevant security requirements as listed below -
o As per [RFC8231], it is RECOMMENDED that these PCEP extensions
only be activated on authenticated and encrypted sessions across
PCEs and PCCs belonging to the same administrative authority,
using Transport Layer Security (TLS) [RFC8253], as per the
recommendations and best current practices in [RFC7525] (unless
explicitly set aside in [RFC8253]).
o Security considerations for path computation requests and
responses are as per [RFC8306].
o Security considerations for stateful operations (such as state
report, synchronization, delegation, update, etc.) are as per
[RFC8231].
o Security considerations for LSP instantiation mechanism are as per
[RFC8231].
o Security considerations as stated in Section 10.1, Section 10.6,
and Section 10.7 of [RFC5440] continue to apply.
13. Acknowledgments
Thanks to Quintin Zhao, Avantika and Venugopal Reddy for the review
comments.
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Thanks to Adrian Farrel (and Jonathan Hardwick) for the review as
document shepherds.
Thanks to Andy Malis for the RTGDIR review. Thanks to Donald
Eastlake for the SECDIR review. Thanks to David Schinazi for the
GENART review.
Thanks to Suresh Krishnan, Mirja Kuhlewind, Roman Danyliw, and
Benjamin Kaduk for the IESG reviews.
14. References
14.1. 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>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
Yasukawa, Ed., "Extensions to Resource Reservation
Protocol - Traffic Engineering (RSVP-TE) for Point-to-
Multipoint TE Label Switched Paths (LSPs)", RFC 4875,
DOI 10.17487/RFC4875, May 2007,
<https://www.rfc-editor.org/info/rfc4875>.
[RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "OSPF Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088,
January 2008, <https://www.rfc-editor.org/info/rfc5088>.
[RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5089, DOI 10.17487/RFC5089,
January 2008, <https://www.rfc-editor.org/info/rfc5089>.
[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>.
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[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>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[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>.
[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>.
[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>.
[RFC8306] Zhao, Q., Dhody, D., Ed., Palleti, R., and D. King,
"Extensions to the Path Computation Element Communication
Protocol (PCEP) for Point-to-Multipoint Traffic
Engineering Label Switched Paths", RFC 8306,
DOI 10.17487/RFC8306, November 2017,
<https://www.rfc-editor.org/info/rfc8306>.
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14.2. Informative References
[RFC4655] Farrel, A., Vasseur, J., 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>.
[RFC5671] Yasukawa, S. and A. Farrel, Ed., "Applicability of the
Path Computation Element (PCE) to Point-to-Multipoint
(P2MP) MPLS and GMPLS Traffic Engineering (TE)", RFC 5671,
DOI 10.17487/RFC5671, October 2009,
<https://www.rfc-editor.org/info/rfc5671>.
[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>.
[I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep-
yang-11 (work in progress), March 2019.
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Appendix A. Contributor Addresses
Yuji Kamite
NTT Communications Corporation
Granpark Tower
3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
EMail: y.kamite@ntt.com
Authors' Addresses
Udayasree Palle
Huawei Technologies
EMail: udayasreereddy@gmail.com
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: dhruv.ietf@gmail.com
Yosuke Tanaka
NTT Communications Corporation
Granpark Tower
3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
EMail: yosuke.tanaka@ntt.com
Vishnu Pavan Beeram
Juniper Networks
EMail: vbeeram@juniper.net
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