Path Computation Element (PCE) Protocol Extensions for Stateful PCE usage for Point-to-Multipoint Traffic Engineering Label Switched Paths
draft-palle-pce-stateful-pce-p2mp-06
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Udayasree Palle , Dhruv Dhody , Yosuke Tanaka , Yuji Kamite , Zafar Ali , Vishnu Pavan Beeram | ||
| Last updated | 2015-04-23 | ||
| Replaced by | draft-ietf-pce-stateful-pce-p2mp, RFC 8623 | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-palle-pce-stateful-pce-p2mp-06
PCE Working Group U. Palle
Internet-Draft D. Dhody
Intended status: Standards Track Huawei Technologies
Expires: October 25, 2015 Y. Tanaka
Y. Kamite
NTT Communications
Z. Ali
Cisco Systems
V. Beeram
Juniper Networks
April 23, 2015
Path Computation Element (PCE) Protocol Extensions for Stateful PCE
usage for Point-to-Multipoint Traffic Engineering Label Switched Paths
draft-palle-pce-stateful-pce-p2mp-06
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 LSPs. This document provides extensions
required for PCEP so as to enable the usage of a stateful PCE
capability in supporting point-to-multipoint (P2MP) TE LSPs.
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 http://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 October 25, 2015.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Supporting P2MP TE LSP for Stateful PCE . . . . . . . . . . . 4
3.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Objectives . . . . . . . . . . . . . . . . . . . . . . . 4
4. Functions to Support P2MP TE LSPs for Stateful PCEs . . . . . 4
5. Architectural Overview of Protocol Extensions . . . . . . . . 5
5.1. Extension of PCEP Messages . . . . . . . . . . . . . . . 5
5.2. Capability Advertisement . . . . . . . . . . . . . . . . 6
5.3. State Synchronization . . . . . . . . . . . . . . . . . . 6
5.4. LSP Delegation . . . . . . . . . . . . . . . . . . . . . 6
5.5. LSP Operations . . . . . . . . . . . . . . . . . . . . . 6
5.5.1. Passive Stateful PCE . . . . . . . . . . . . . . . . 7
5.5.2. Active Stateful PCE . . . . . . . . . . . . . . . . . 7
6. PCEP Object Extensions . . . . . . . . . . . . . . . . . . . 7
6.1. Extension of LSP Object . . . . . . . . . . . . . . . . . 7
6.2. P2MP-LSP-IDENTIFIER TLV . . . . . . . . . . . . . . . . . 8
6.3. S2LS Object . . . . . . . . . . . . . . . . . . . . . . . 10
7. PCEP Message Extensions . . . . . . . . . . . . . . . . . . . 11
7.1. The PCRpt Message . . . . . . . . . . . . . . . . . . . . 11
7.2. The PCUpd Message . . . . . . . . . . . . . . . . . . . . 13
7.3. The PCReq Message . . . . . . . . . . . . . . . . . . . . 14
7.4. The PCRep Message . . . . . . . . . . . . . . . . . . . . 15
7.5. Example . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.5.1. P2MP TE LSP Update Request . . . . . . . . . . . . . 16
7.5.2. P2MP TE LSP Report . . . . . . . . . . . . . . . . . 16
7.6. Report and Update Message Fragmentation . . . . . . . . . 17
7.6.1. Report Fragmentation Procedure . . . . . . . . . . . 18
7.6.2. Update Fragmentation Procedure . . . . . . . . . . . 18
8. Non-Support of P2MP TE LSPs for Stateful PCE . . . . . . . . 18
9. Manageability Considerations . . . . . . . . . . . . . . . . 19
9.1. Control of Function and Policy . . . . . . . . . . . . . 19
9.2. Information and Data Models . . . . . . . . . . . . . . . 19
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 19
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 19
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9.5. Requirements On Other Protocols . . . . . . . . . . . . . 20
9.6. Impact On Network Operations . . . . . . . . . . . . . . 20
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
10.1. STATEFUL-PCE-CAPABILITY TLV . . . . . . . . . . . . . . 20
10.2. Extension of LSP Object . . . . . . . . . . . . . . . . 20
10.3. Extension of PCEP-Error Object . . . . . . . . . . . . . 21
10.4. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 21
11. Security Considerations . . . . . . . . . . . . . . . . . . . 22
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
13.1. Normative References . . . . . . . . . . . . . . . . . . 22
13.2. Informative References . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
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.
[RFC4857] 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. The
PCE has been identified as a suitable application for the computation
of paths for P2MP TE LSPs ([RFC5671]).
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 [RFC6006].
Stateful PCEs are shown to be helpful in many application scenarios,
in both MPLS and GMPLS networks, as illustrated in
[I-D.ietf-pce-stateful-pce-app]. These scenarios apply equally to
P2P and P2MP TE LSPs. [I-D.ietf-pce-stateful-pce] provides the
fundamental extensions needed for stateful PCE to support general
functionality for P2P TE LSP. Complementarily, this document focuses
on the extensions that are necessary in order for the deployment of
stateful PCEs to support P2MP TE LSPs.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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2. Terminology
Terminology used in this document is same as terminology used in
[I-D.ietf-pce-stateful-pce] and [RFC6006].
3. Supporting P2MP TE LSP for Stateful PCE
3.1. Motivation
[I-D.ietf-pce-stateful-pce-app] 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. [I-D.ietf-pce-stateful-pce] defines the
extensions to PCEP for P2P TE LSPs. Complementarily, this document
focuses on the 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 PLSP-ID. For P2MP this is an added advantage, where
the size of message is much larger. Incase of stateless PCE, a
modification of P2MP tree requires encoding of all leaves along with
the paths in PCReq message, but using a stateful PCE with P2MP
capability, the PCEP message can be used to convey only the
modifications (the other information can be retrieved from the P2MP
LSP identifier in the LSP database (LSPDB)).
3.2. Objectives
The objectives for the protocol extensions to support P2MP TE LSP for
stateful PCE are same as the objectives described in section 3.2 of
[I-D.ietf-pce-stateful-pce].
4. Functions to Support P2MP TE LSPs for Stateful PCEs
[I-D.ietf-pce-stateful-pce] 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 PCEP
Stateful PCE extensions for P2MP using mechanisms defined in
Section 5.2.
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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 LSP.
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 5.5 of
[I-D.ietf-pce-stateful-pce]); the PCC may withdraw the delegation
or the PCE may give up the delegation at any time.
[Editor's Note - An update to [I-D.sivabalan-pce-disco-stateful] is
needed to support autodiscovery of stateful PCEs with P2MP
capability. This can be undertaken after WG adoption.]
5. Architectural Overview of Protocol Extensions
5.1. Extension of PCEP Messages
New PCEP messages are defined in [I-D.ietf-pce-stateful-pce] 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 can contain actual P2MP TE LSP path attributes,
LSP status, etc. An LSP State Report carried on 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 7.1.
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 on 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 7.2.
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5.2. Capability Advertisement
During PCEP Initialization Phase, as per Section 7.1.1 of
[I-D.ietf-pce-stateful-pce], PCEP speakers advertises Stateful
capability via Stateful PCE Capability TLV in open message. Two new
flags are defined for the STATEFUL-PCE-CAPABILITY TLV defined in
[I-D.ietf-pce-stateful-pce] and updated in
[I-D.ietf-pce-pce-initiated-lsp] and
[I-D.ietf-pce-stateful-sync-optimizations].
Two new bits N (P2MP-CAPABILITY) and M (P2MP-LSP-UPDATE-CAPABILITY)
are added in this document:
N (P2MP-CAPABILITY - 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 P2MP LSP parameters or operational status changes.; if
set to 1 by a PCE, the N Flag indicates that the PCE is interested
in receiving LSP State Reports whenever LSP parameters or
operational status changes. 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 - 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.
A PCEP speaker should continue to advertise the basic P2MP capability
via mechanisms as described in [RFC6006].
5.3. State Synchronization
State Synchronization operations described in Section 5.4 of
[I-D.ietf-pce-stateful-pce] are applicable for P2MP TE LSPs as well.
5.4. LSP Delegation
LSP delegation operations described in Section 5.5 of
[I-D.ietf-pce-stateful-pce] are applicable for P2MP TE LSPs as well.
5.5. LSP Operations
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5.5.1. Passive Stateful PCE
LSP operations for passive stateful PCE described in Section 5.6.1 of
[I-D.ietf-pce-stateful-pce] are applicable for P2MP TE LSPs as well.
The Path Computation Request and Response message format for P2MP TE
LSPs is described in Section 3.4 and Section 3.5 of [RFC6006]
respectively.
The Request and Response message for P2MP TE LSPs are extended to
support encoding of LSP object, so that it is possible to refer to a
LSP with a unique identifier and simplify the PCEP message exchange.
For example, incase of modification of one leaf in a P2MP tree, there
should be no need to carry the full P2MP tree in PCReq message.
The extension for the Request and Response message for passive
stateful operations on P2MP TE LSPs are described in Section 7.3 and
Section 7.4. The extension for the Path Computation LSP State Report
(PCRpt) message is described in Section 7.1.
5.5.2. Active Stateful PCE
LSP operations for active stateful PCE described in Section 5.6.2 of
[I-D.ietf-pce-stateful-pce] 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 7.2.
6. PCEP Object Extensions
The PCEP TLV defined in this document is compliant with the PCEP TLV
format defined in [RFC5440].
6.1. Extension of LSP Object
LSP Object is defined in Section 7.3 of [I-D.ietf-pce-stateful-pce].
It specifies PLSP-ID to uniquely identify an LSP that is constant for
the life time of a PCEP session. Similarly for P2MP tunnel, PLSP-ID
identify a P2MP TE LSP uniquely. This document adds the following
flags to the LSP Object:
N (P2MP bit): If the bit is set to 1, it specifies the message is
for P2MP TE LSP which MUST be set in PCRpt or PCUpd message for a
P2MP TE LSP.
F (Fragmentation bit): If the bit is set to 1, it specifies the
message is fragmented.
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If P2MP bit is set, the following P2MP-LSP-IDENTIFIER TLV MUST be
present in LSP object.
6.2. P2MP-LSP-IDENTIFIER TLV
The P2MP LSP Identifier TLV MUST be included in the LSP object in
PCRpt message for RSVP-signaled P2MP TE LSPs. If the TLV is missing,
the PCE will generate an error with error-type 6 (mandatory object
missing) and error-value TBD (P2MP-LSP-IDENTIFIERS TLV missing) and
close the PCEP session.
The P2MP LSP Identifier TLV MAY be included in the LSP object in
PCUpd message for RSVP-signaled P2MP TE LSPs. The special value of
all zeros for this TLV is used to refer to all paths pertaining to a
particular PLSP-ID.
There are two P2MP LSP Identifier TLVs, one for IPv4 and one for
IPv6.
The format of the IPV4-P2MP-LSP-IDENTIFIER TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length=16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Tunnel Sender Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP ID | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| P2MP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: IPV4-P2MP-LSP-IDENTIFIER TLV format
The type of the TLV is [TBD] and it has a fixed length 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.
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LSP ID: contains the 16-bit 'LSP ID' identifier defined in
[RFC3209], Section 4.6.2.1 for the LSP_TUNNEL_IPv4 Sender Template
Object.
Tunnel ID: contains the 16-bit 'Tunnel ID' identifier defined in
[RFC3209], Section 4.6.1.1 for the LSP_TUNNEL_IPv4 Session Object.
Tunnel ID remains constant over the life time of a tunnel.
Extended Tunnel ID: contains the 32-bit 'Extended Tunnel ID'
identifier defined in [RFC3209], Section 4.6.1.1 for the
LSP_TUNNEL_IPv4 Session Object.
P2MP ID: contains the 32-bit '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-IDENTIFIER TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length=40 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| IPv6 tunnel sender address |
+ (16 octets) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP ID | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| Extended Tunnel ID |
+ (16 octets) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| P2MP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: IPV6-P2MP-LSP-IDENTIFIER TLV format
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The type of the TLV is [TBD] and it 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.
LSP ID: contains the 16-bit 'LSP ID' identifier defined in
[RFC3209], Section 4.6.2.2 for the LSP_TUNNEL_IPv6 Sender Template
Object.
Tunnel ID: contains the 16-bit 'Tunnel ID' identifier defined in
[RFC3209], Section 4.6.1.2 for the LSP_TUNNEL_IPv6 Session Object.
Tunnel ID remains constant over the life time of a tunnel.
Extended Tunnel ID: contains the 128-bit '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.
6.3. S2LS Object
The S2LS (Source-to-Leaves) Object is used to report RSVP-TE state of
one or more destiantions (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 bit is set in LSP object.
S2LS Object-Class is [TBD].
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 3: S2LS object format
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Flags(32 bits):
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
[I-D.ietf-pce-stateful-pce].
When N bit 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.
Future documents MAY define optional TLVs that MAY be included in the
S2LS Object.
7. PCEP Message Extensions
7.1. The PCRpt Message
As per Section 6.1 of [I-D.ietf-pce-stateful-pce], 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 LSP.
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>
<end-point-path-pair-list>
<attribute-list>
Where:
<end-point-path-pair-list>::=
[<END-POINTS>]
[<S2LS>]
<path>
[<end-point-path-pair-list>]
<path> ::= (<ERO>|<SERO>)
[<RRO>]
[<path>]
<attribute-list> is defined in [RFC5440] and
extended by PCEP extensions.
The P2MP END-POINTS object defined in [RFC6006]is mandatory for
specifying address of P2MP leaves grouped based on leaf types.
o New leaves to add (leaf type = 1)
o Old leaves to remove (leaf type = 2)
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 are
grouped in END-POINTS object based on the operational status (O field
in S2LS object) and leaf type (in END-POINTS). This way the leaves
that share the same operational status are grouped together. For
reporing the status of delegated P2MP TE LSP, leaf-type = 3, where as
for non-delegated P2MP TE LSP, leaf-type = 4 is used.
For delegated P2MP TE LSP configuration changes are reported via
PCRpt message. For example, adding of new leaves END-POINTS (leaf-
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type = 1) is used where as removing of old leaves (leaf-type = 2) is
used.
Note that we preserve compatibility with the
[I-D.ietf-pce-stateful-pce] definition of <state-report>. At least
one instance of <END-POINTS> MUST be present in this message for P2MP
LSP.
During state synchronization, the PCRpt message must report the
status of the full P2MP TE LSP.
The S2LS object MUST be carried in PCRpt message along with END-
POINTS object when N bit is set in LSP object for P2MP TE LSP. If
the S2LS object is missing, the receiving PCE MUST send a PCErr
message with Error-type=6 (Mandatory Object missing) and Error-
value=TBD (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].
7.2. The PCUpd Message
As per Section 6.2 of [I-D.ietf-pce-stateful-pce], PCUpd message is
used to update P2P TE LSP attributes. This document extends the
PCUpd message in updating the attributes of P2MP TE LSP.
The format of a PCUpd message is as follows:
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<PCUpd Message> ::= <Common Header>
<update-request-list>
Where:
<update-request-list> ::= <update-request>
[<update-request-list>]
<update-request> ::= <SRP>
<LSP>
<end-point-path-pair-list>
<attribute-list>
Where:
<end-point-path-pair-list>::=
[<END-POINTS>]
<path>
[<end-point-path-pair-list>]
<path> ::= (<ERO>|<SERO>)
[<path>]
<attribute-list> is defined in [RFC5440] and
extended by PCEP extensions.
Note that we preserve compatibility with the
[I-D.ietf-pce-stateful-pce] definition of <update-request>.
The PCC MAY 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 bit is
set in LSP object for 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].
7.3. The PCReq Message
As per Section 3.4 of [RFC6006], 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:
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<PCReq Message>::= <Common Header>
<request>
where:
<request>::= <RP>
<end-point-rro-pair-list>
[<LSP>]
[<OF>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>]
[<LOAD-BALANCING>]
where:
<end-point-rro-pair-list>::=<END-POINTS>[<RRO-List>][<BANDWIDTH>]
[<end-point-rro-pair-list>]
<RRO-List>::=<RRO>[<BANDWIDTH>][<RRO-List>]
<metric-list>::=<METRIC>[<metric-list>]
7.4. The PCRep Message
As per Section 3.5 of [RFC6006], 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
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:
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<PCRep Message>::= <Common Header>
<response>
<response>::=<RP>
[<end-point-path-pair-list>]
[<NO-PATH>]
[<attribute-list>]
where:
<end-point-path-pair-list>::=
[<END-POINTS>]<path>[<end-point-path-pair-list>]
<path> ::= (<ERO>|<SERO>) [<path>]
<attribute-list>::=[<LSP>]
[<OF>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>]
7.5. Example
7.5.1. P2MP TE LSP Update Request
LSP Update Request message is sent by an active stateful PCE to
update the P2MP TE LSP parameters or attributes. An example of a
PCUpd message for P2MP TE LSP 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 request updation of path taken by
some of the leaves in a P2MP tree. The update request uses the END-
POINT type 3 (modified/reoptimized). The ERO list represents the
S2LS path after modification. The update message does not need to
encode the full P2MP tree in this case.
7.5.2. P2MP TE LSP Report
LSP State Report message is sent by a PCC to report or delegate the
P2MP TE LSP. An example of a PCRpt message for a delegated P2MP TE
LSP is described below to add new leaves to an existing P2MP TE LSP:
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Common Header
LSP with P2MP flag set
END-POINTS for leaf type 1
S2LS (O=DOWN)
ERO list (empty)
An example of a PCRpt message for 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
S2LS (O=UP)
ERO list
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:
Common Header
LSP with P2MP flag set
END-POINTS for leaf type 3
S2LS (O=UP)
ERO list
END-POINTS for leaf type 3
S2LS (O=DOWN)
ERO list
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
S2LS (O=ACTIVE)
ERO list
END-POINTS for leaf type 4
S2LS (O=DOWN)
ERO list
7.6. Report and Update Message Fragmentation
The total PCEP message length, including the common header, is 16
bytes. In certain scenarios the P2MP report and update request may
not fit into a single PCEP message (initial report or update). The
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F-bit is used in the LSP object to signal that the initial report or
update 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.
Fragmentation procedure described below for report or update message
is similar to [RFC6006]which describes request and response message
fragmentation.
7.6.1. 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-bit 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.
To indicate P2MP message fragmentation errors associated with a P2MP
Report, a Error-Type (18) and a new error-value TBD is used if a PCE
has not received the last piece of the fragmented message, it should
send an error message to the PCC to signal that it has received an
incomplete message (i.e., "Fragmented Report failure").
7.6.2. 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-bit 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.
To indicate P2MP message fragmentation errors associated with a P2MP
Update request, a Error-Type (18) and a new error-value TBD is used
if a PCC has not received the last piece of the fragmented message,
it should send an error message to the PCE to signal that it has
received an incomplete message (i.e., "Fragmented Update failure").
8. Non-Support of P2MP TE LSPs for Stateful PCE
The PCEP protocol 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 PCEP
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Speaker on the PCC supports the extensions of this draft (understands
the P2MP flag 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 TBD (Attempted LSP Update Request for P2MP if active
stateful PCE capability for P2MP was not advertised). If the PCEP
Speaker on the PCE supports the extensions of this draft (understands
the P2MP 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 TBD (Attempted LSP State Report for P2MP if stateful PCE
capability for P2MP was not advertised) and it will terminate the
PCEP session.
If a Stateful PCE receives a P2MP TE LSP report message and the PCE
does not understand the P2MP flag in the LSP object, and therefore
the PCEP extensions described in this document, then the Stateful PCE
would act as per [I-D.ietf-pce-stateful-pce].
9. Manageability Considerations
All manageability requirements and considerations listed in
[RFC5440], [RFC6006] and [I-D.ietf-pce-stateful-pce] apply to PCEP
protocol extensions defined in this document. In addition,
requirements and considerations listed in this section apply.
9.1. Control of Function and Policy
A PCE or PCC implementation MUST allow configuring the stateful PCEP
capability and the LSP Update capability for P2MP LSPs.
9.2. Information and Data Models
The PCEP MIB module SHOULD be extended to include advertised P2MP
stateful capabilities, P2MP synchronization status, and P2MP
delegation status etc.
9.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already
listed in [RFC5440].
9.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440], [RFC6006] and [I-D.ietf-pce-stateful-pce].
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9.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
9.6. Impact On Network Operations
Mechanisms defined in this document do not have any impact on network
operations in addition to those already listed in [RFC5440],
[RFC6006] and [I-D.ietf-pce-stateful-pce].
10. IANA Considerations
This document requests IANA actions to allocate code points for the
protocol elements defined in this document. Values shown here are
suggested for use by IANA.
10.1. STATEFUL-PCE-CAPABILITY TLV
The following values are defined in this document for the Flags field
in the STATEFUL-PCE-CAPABILITY-TLV in the OPEN object:
Bit Description Reference
TBD P2MP-CAPABILITY This.I-D
TBD P2MP-LSP-UPDATE- This.I-D
CAPABILITY
10.2. Extension of LSP Object
This document requests that a registry is created to manage the Flags
field of the LSP object. New values are to be assigned by Standards
Action [RFC5226]. 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
TBD P2MP This.I-D
TBD Fragmentation This.I-D
10.3. Extension of PCEP-Error Object
A new error types 6 and 19 defined in section 8.4 of
[I-D.ietf-pce-stateful-pce]. This document extend the new Error-
Values for those error types for the following error conditions:
Error-Type Meaning
6 Mandatory Object missing
Error-value=TBD: S2LS object missing
Error-value=TBD: P2MP-LSP-IDENTIFIER TLV missing
18 P2MP Fragmentation Error
Error-value= TBD. Fragmented Report
failure
Error-value= TBD. Fragmented Update
failure
19 Invalid Operation
Error-value= TBD. Attempted LSP State Report
for P2MP if stateful PCE capability
for P2MP was not advertised
Error-value= TBD. Attempted LSP Update Request
for P2MP if active stateful PCE capability
for P2MP was not advertised
10.4. PCEP TLV Type Indicators
This document defines the following new PCEP TLVs:
Value Meaning Reference
TBD P2MP-IPV4-LSP-IDENTIFIERS This.I-D
TBD P2MP-IPV6-LSP-IDENTIFIERS This.I-D
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11. Security Considerations
The stateful operations on P2MP TE LSP are more CPU-intensive and
also utilize more link bandwidth. In the event of an unauthorized
stateful P2MP operations, or a denial of service attack, the
subsequent PCEP operations may be disruptive to the network.
Consequently, it is important that implementations conform to the
relevant security requirements of [RFC5440], [RFC6006] and
[I-D.ietf-pce-stateful-pce].
12. Acknowledgments
Thanks to Quintin Zhao and Venugopal Reddy for his comments.
13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", RFC 5440, March
2009.
[RFC6006] Zhao, Q., King, D., Verhaeghe, F., Takeda, T., Ali, Z.,
and J. Meuric, "Extensions to the Path Computation Element
Communication Protocol (PCEP) for Point-to-Multipoint
Traffic Engineering Label Switched Paths", RFC 6006,
September 2010.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-11 (work in progress), April 2015.
13.2. Informative References
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC4857] Fogelstroem, E., Jonsson, A., and C. Perkins, "Mobile IPv4
Regional Registration", RFC 4857, June 2007.
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[RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa,
"Extensions to Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5671] Yasukawa, S. and A. Farrel, "Applicability of the Path
Computation Element (PCE) to Point-to-Multipoint (P2MP)
MPLS and GMPLS Traffic Engineering (TE)", RFC 5671,
October 2009.
[I-D.ietf-pce-stateful-pce-app]
Zhang, X. and I. Minei, "Applicability of a Stateful Path
Computation Element (PCE)", draft-ietf-pce-stateful-pce-
app-03 (work in progress), October 2014.
[I-D.ietf-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-ietf-pce-pce-initiated-lsp-04 (work in
progress), April 2015.
[I-D.ietf-pce-stateful-sync-optimizations]
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", draft-
ietf-pce-stateful-sync-optimizations-02 (work in
progress), January 2015.
[I-D.sivabalan-pce-disco-stateful]
Sivabalan, S., Medved, J., and X. Zhang, "IGP Extensions
for Stateful PCE Discovery", draft-sivabalan-pce-disco-
stateful-03 (work in progress), January 2014.
Authors' Addresses
Udayasree Palle
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037
India
EMail: udayasree.palle@huawei.com
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Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037
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
Yuji Kamite
NTT Communications Corporation
Granpark Tower
3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
EMail: y.kamite@ntt.com
Zafar Ali
Cisco Systems
EMail: zali@cisco.com
Vishnu Pavan Beeram
Juniper Networks
EMail: vbeeram@juniper.net
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