draft-ietf-pce-stateful-sync-optimizations-08.txt   draft-ietf-pce-stateful-sync-optimizations-09.txt 
PCE Working Group E. Crabbe PCE Working Group E. Crabbe
Internet-Draft Oracle Internet-Draft Oracle
Intended status: Standards Track I. Minei Intended status: Standards Track I. Minei
Expires: July 27, 2017 Google, Inc. Expires: September 1, 2017 Google, Inc.
J. Medved J. Medved
Cisco Systems, Inc. Cisco Systems, Inc.
R. Varga R. Varga
Pantheon Technologies SRO Pantheon Technologies SRO
X. Zhang X. Zhang
D. Dhody D. Dhody
Huawei Technologies Huawei Technologies
January 23, 2017 February 28, 2017
Optimizations of Label Switched Path State Synchronization Procedures Optimizations of Label Switched Path State Synchronization Procedures
for a Stateful PCE for a Stateful PCE
draft-ietf-pce-stateful-sync-optimizations-08 draft-ietf-pce-stateful-sync-optimizations-09
Abstract Abstract
A stateful Path Computation Element (PCE) has access to not only the A stateful Path Computation Element (PCE) has access to not only the
information disseminated by the network's Interior Gateway Protocol information disseminated by the network's Interior Gateway Protocol
(IGP), but also the set of active paths and their reserved resources (IGP), but also the set of active paths and their reserved resources
for its computation. The additional Label Switched Path (LSP) state for its computation. The additional Label Switched Path (LSP) state
information allows the PCE to compute constrained paths while information allows the PCE to compute constrained paths while
considering individual LSPs and their interactions. This requires a considering individual LSPs and their interactions. This requires a
reliable state synchronization mechanism between the PCE and the state synchronization mechanism between the PCE and the network, PCE
network, PCE and path computation clients (PCCs), and between and path computation clients (PCCs), and between cooperating PCEs.
cooperating PCEs. The basic mechanism for state synchronization is The basic mechanism for state synchronization is part of the stateful
part of the stateful PCE specification. This draft presents PCE specification. This document presents motivations for
motivations for optimizations to the base state synchronization optimizations to the base state synchronization procedure and
procedure and specifies the required Path Computation Element specifies the required Path Computation Element Communication
Communication Protocol (PCEP) extensions. Protocol (PCEP) extensions.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 2, line 12 skipping to change at page 2, line 12
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 27, 2017. This Internet-Draft will expire on September 1, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 36 skipping to change at page 2, line 36
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. State Synchronization Avoidance . . . . . . . . . . . . . . . 4 3. State Synchronization Avoidance . . . . . . . . . . . . . . . 4
3.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. State Synchronization Avoidance Procedure . . . . . . . . 4 3.2. State Synchronization Avoidance Procedure . . . . . . . . 4
3.3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . 9 3.2.1. IP Address change during session re-establishment . . 9
3.3.1. LSP State Database Version Number TLV . . . . . . . . 9 3.3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . 10
3.3.2. Speaker Entity Identifier TLV . . . . . . . . . . . . 10 3.3.1. LSP State Database Version Number TLV . . . . . . . . 10
4. Incremental State Synchronization . . . . . . . . . . . . . . 11 3.3.2. Speaker Entity Identifier TLV . . . . . . . . . . . . 11
4. Incremental State Synchronization . . . . . . . . . . . . . . 12
4.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 12 4.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 12
4.2. Incremental Synchronization Procedure . . . . . . . . . . 13 4.2. Incremental Synchronization Procedure . . . . . . . . . . 13
5. PCE-triggered Initial Synchronization . . . . . . . . . . . . 15 5. PCE-triggered Initial Synchronization . . . . . . . . . . . . 16
5.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 15 5.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 16
5.2. PCE-triggered Initial State Synchronization Procedure . . 15 5.2. PCE-triggered Initial State Synchronization Procedure . . 17
6. PCE-triggered Re-synchronization . . . . . . . . . . . . . . 16 6. PCE-triggered Re-synchronization . . . . . . . . . . . . . . 18
6.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 16 6.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 18
6.2. PCE-triggered State Re-synchronization Procedure . . . . 16 6.2. PCE-triggered State Re-synchronization Procedure . . . . 18
7. Advertising Support of Synchronization Optimizations . . . . 17 7. Advertising Support of Synchronization Optimizations . . . . 19
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
8.1. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 18 8.1. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 20
8.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 19 8.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 21
8.3. STATEFUL-PCE-CAPABILITY TLV . . . . . . . . . . . . . . . 19 8.3. STATEFUL-PCE-CAPABILITY TLV . . . . . . . . . . . . . . . 21
9. Manageability Considerations . . . . . . . . . . . . . . . . 20 9. Manageability Considerations . . . . . . . . . . . . . . . . 21
9.1. Control of Function and Policy . . . . . . . . . . . . . 20 9.1. Control of Function and Policy . . . . . . . . . . . . . 21
9.2. Information and Data Models . . . . . . . . . . . . . . . 20 9.2. Information and Data Models . . . . . . . . . . . . . . . 21
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 20 9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 22
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 20 9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 22
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 20 9.5. Requirements On Other Protocols . . . . . . . . . . . . . 22
9.6. Impact On Network Operations . . . . . . . . . . . . . . 21 9.6. Impact On Network Operations . . . . . . . . . . . . . . 22
10. Security Considerations . . . . . . . . . . . . . . . . . . . 21 10. Security Considerations . . . . . . . . . . . . . . . . . . . 22
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 23
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
13.1. Normative References . . . . . . . . . . . . . . . . . . 21 13.1. Normative References . . . . . . . . . . . . . . . . . . 23
13.2. Informative References . . . . . . . . . . . . . . . . . 22 13.2. Informative References . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
The Path Computation Element Communication Protocol (PCEP) provides The Path Computation Element Communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path mechanisms for Path Computation Elements (PCEs) to perform path
computations in response to Path Computation Clients (PCCs) requests. computations in response to Path Computation Clients (PCCs) requests.
[I-D.ietf-pce-stateful-pce] describes a set of extensions to PCEP to [I-D.ietf-pce-stateful-pce] describes a set of extensions to PCEP to
provide stateful control. A stateful PCE has access to not only the provide stateful control. A stateful PCE has access to not only the
information carried by the network's Interior Gateway Protocol (IGP), information carried by the network's Interior Gateway Protocol (IGP),
but also the set of active paths and their reserved resources for its but also the set of active paths and their reserved resources for its
computations. The additional state allows the PCE to compute computations. The additional state allows the PCE to compute
constrained paths while considering individual LSPs and their constrained paths while considering individual LSPs and their
interactions. This requires a reliable state synchronization interactions. This requires a state synchronization mechanism
mechanism between the PCE and the network, PCE and PCC, and between between the PCE and the network, PCE and PCC, and between cooperating
cooperating PCEs. [I-D.ietf-pce-stateful-pce] describes the basic PCEs. [I-D.ietf-pce-stateful-pce] describes the basic mechanism for
mechanism for state synchronization. This draft specifies following state synchronization. This document specifies following
optimizations for state synchronization and the corresponding PCEP optimizations for state synchronization and the corresponding PCEP
procedures and extensions: procedures and extensions:
o State Synchronization Avoidance: To skip state synchronization if o State Synchronization Avoidance: To skip state synchronization if
the state has survived and not changed during session restart. the state has survived and not changed during session restart.
(See Section 3.) (See Section 3.)
o Incremental State Synchronization: To do incremental (delta) state o Incremental State Synchronization: To do incremental (delta) state
synchronization when possible. (See Section 4.) synchronization when possible. (See Section 4.)
o PCE-triggered Initial Synchronization: To let PCE control the o PCE-triggered Initial Synchronization: To let PCE control the
timing of the initial state synchronization. (See Section 5.) timing of the initial state synchronization. (See Section 5.)
o PCE-triggered Re-synchronization: To let PCE re-synchronize the o PCE-triggered Re-synchronization: To let PCE re-synchronize the
state for sanity check. (See Section 6.) state for sanity check. (See Section 6.)
Support for each of the synchronization optimization capabilities is
advertised during the PCEP initialization phase. See Section 7 for
the new flags defined in this document. The handling of each flag is
described in the relevant section.
2. Terminology 2. Terminology
This document uses the following terms defined in [RFC5440]: PCC, This document uses the following terms defined in [RFC5440]: PCC,
PCE, PCEP Peer. PCE, PCEP Peer.
This document uses the following terms defined in [RFC8051]: Stateful
PCE, Delegation, LSP State Database.
This document uses the following terms defined in This document uses the following terms defined in
[I-D.ietf-pce-stateful-pce]: Delegation, Redelegation Timeout [I-D.ietf-pce-stateful-pce]: Redelegation Timeout Interval, LSP State
Interval, LSP State Report, LSP Update Request, LSP State Database. Report, LSP Update Request.
Within this document, when describing PCE-PCE communications, the Within this document, when describing PCE-PCE communications, one of
requesting PCE fills the role of a PCC. This provides a saving in the PCEs fills the role of a PCC. This provides a saving in
documentation without loss of function. documentation without loss of function.
3. State Synchronization Avoidance 3. State Synchronization Avoidance
3.1. Motivation 3.1. Motivation
The purpose of state synchronization is to provide a checkpoint-in- The purpose of state synchronization is to provide a checkpoint-in-
time state replica of a PCC's LSP state in a stateful PCE. State time state replica of a PCC's LSP state in a stateful PCE. State
synchronization is performed immediately after the initialization synchronization is performed immediately after the initialization
phase ([RFC5440]). [I-D.ietf-pce-stateful-pce] describes the basic phase ([RFC5440]). [I-D.ietf-pce-stateful-pce] describes the basic
skipping to change at page 4, line 44 skipping to change at page 5, line 5
3.2. State Synchronization Avoidance Procedure 3.2. State Synchronization Avoidance Procedure
State synchronization MAY be skipped following a PCEP session restart State synchronization MAY be skipped following a PCEP session restart
if the state of both PCEP peers did not change during the period if the state of both PCEP peers did not change during the period
prior to session re-initialization. To be able to make this prior to session re-initialization. To be able to make this
determination, state must be exchanged and maintained by both PCE and determination, state must be exchanged and maintained by both PCE and
PCC during normal operation. This is accomplished by keeping track PCC during normal operation. This is accomplished by keeping track
of the changes to the LSP state database, using a version tracking of the changes to the LSP state database, using a version tracking
field called the LSP State Database Version Number. field called the LSP State Database Version Number.
The LSP State Database Version Number, carried in LSP-DB-VERSION TLV The INCLUDE-DB-VERSION (S) bit in the stateful PCE capability TLV
(see Section 3.3.1), is owned by a PCC and it MUST be incremented by (Section 7) is advertised on a PCEP session during session startup to
1 for each successive change in the PCC's LSP state database. The indicate that the LSP State Database Version Number is to be included
LSP State Database Version Number MUST start at 1 and may wrap when the LSPs are reported to the PCE. The LSP State Database
around. Values 0 and 0xFFFFFFFFFFFFFFFF are reserved. If either of Version Number, carried in LSP-DB-VERSION TLV (see Section 3.3.1), is
the two values are used during LSP state (re)-synchronization, the owned by a PCC and it MUST be incremented by 1 for each successive
PCE speaker receiving this node should send back a PCErr with Error- change in the PCC's LSP state database. The LSP State Database
type 20 Error-value TBD (suggested value - 6) 'Received an invalid Version Number MUST start at 1 and may wrap around. Values 0 and
LSP DB Version Number', and close the PCEP session. Operations that 0xFFFFFFFFFFFFFFFF are reserved. If either of the two values are
trigger a change to the local LSP state database include a change in used during LSP state (re)-synchronization, the PCE speaker receiving
the LSP operational state, delegation of an LSP, removal or setup of this value MUST send back a PCErr with Error-type 20 Error-value TBD6
an LSP or change in any of the LSP attributes that would trigger a (suggested value - 6) 'Received an invalid LSP DB Version Number',
report to the PCE. and close the PCEP session. Operations that trigger a change to the
local LSP state database include a change in the LSP operational
If state synchronization avoidance is enabled, a PCC MUST increment state, delegation of an LSP, removal or setup of an LSP or change in
its LSP State Database Version Number when the 'Redelegation Timeout any of the LSP attributes that would trigger a report to the PCE.
Interval' timer expires (see [I-D.ietf-pce-stateful-pce]) for the use
of the Redelegation Timeout Interval).
State synchronization avoidance is advertised on a PCEP session If the include LSP DB version capability is enabled, a PCC MUST
during session startup using the INCLUDE-DB-VERSION (S) bit in the increment its LSP State Database Version Number when the
capabilities TLV (see Section 7). The peer may move in the network, 'Redelegation Timeout Interval' timer expires (see
either physically or logically, which may cause its connectivity [I-D.ietf-pce-stateful-pce] for the use of the Redelegation Timeout
details and transport-level identity (such as IP address) to change. Interval).
To ensure that a PCEP peer can recognize a previously connected peer
even in face of such mobility, each PCEP peer includes the SPEAKER-
ENTITY-ID TLV described in Section 3.3.2 in the OPEN message.
If both PCEP speakers set the S flag in the OPEN object's STATEFUL- If both PCEP speakers set the S flag in the OPEN object's STATEFUL-
PCE-CAPABILITY TLV to 1, the PCC MUST include the LSP-DB-VERSION TLV PCE-CAPABILITY TLV to 1, the PCC MUST include the LSP-DB-VERSION TLV
in each LSP object of the PCRpt message. If the LSP-DB-VERSION TLV in each LSP object of the PCRpt message. If the LSP-DB-VERSION TLV
is missing in a PCRpt message, the PCE will generate an error with is missing in a PCRpt message, the PCE will generate an error with
Error-Type 6 (mandatory object missing) and Error-Value TBD Error-Type 6 (mandatory object missing) and Error-Value TBD1
(suggested value - 12) 'LSP-DB-VERSION TLV missing' and close the (suggested value - 12) 'LSP-DB-VERSION TLV missing' and close the
session. If state synchronization avoidance has not been enabled on session. If the include LSP DB version capability has not been
a PCEP session, the PCC SHOULD NOT include the LSP-DB-VERSION TLV in enabled on a PCEP session, the PCC SHOULD NOT include the LSP-DB-
the LSP Object and the PCE SHOULD ignore it were it to receive one. VERSION TLV in the LSP Object and the PCE MUST ignore it were it to
receive one.
If a PCE's LSP state database survived the restart of a PCEP session, If a PCE's LSP state database survived the restart of a PCEP session,
the PCE will include the LSP-DB-VERSION TLV in its OPEN object, and the PCE will include the LSP-DB-VERSION TLV in its OPEN object, and
the TLV will contain the last LSP State Database Version Number the TLV will contain the last LSP State Database Version Number
received on an LSP State Report from the PCC in the previous PCEP received on an LSP State Report from the PCC in the previous PCEP
session. If a PCC's LSP State Database survived the restart of a session. If a PCC's LSP State Database survived the restart of a
PCEP session, the PCC will include the LSP-DB-VERSION TLV in its OPEN PCEP session, the PCC will include the LSP-DB-VERSION TLV in its OPEN
object and the TLV will contain the latest LSP State Database Version object and the TLV will contain the latest LSP State Database Version
Number. If a PCEP speaker's LSP state database did not survive the Number. If a PCEP speaker's LSP state database did not survive the
restart of a PCEP session, the PCEP speaker MUST NOT include the LSP- restart of a PCEP session or at startup when the database is empty,
DB-VERSION TLV in the OPEN object. the PCEP speaker MUST NOT include the LSP-DB-VERSION TLV in the OPEN
object.
If both PCEP speakers include the LSP-DB-VERSION TLV in the OPEN If both PCEP speakers include the LSP-DB-VERSION TLV in the OPEN
Object and the TLV values match, the PCC MAY skip state Object and the TLV values match, the PCC MAY skip state
synchronization. Otherwise, the PCC MUST perform full state synchronization and the PCE does not wait for the end of
synchronization (see [I-D.ietf-pce-stateful-pce]) or incremental synchronization marker [I-D.ietf-pce-stateful-pce]. Otherwise, the
state synchronization (see Section 4) to the stateful PCE. If the PCC MUST perform full state synchronization (see
PCC attempts to skip state synchronization, by setting the SYNC Flag [I-D.ietf-pce-stateful-pce]) or incremental state synchronization
to 0 and PLSP-ID to a non-zero value on the first LSP State Report (see Section 4 if this capability is advertised) to the stateful PCE.
from the PCC as per [I-D.ietf-pce-stateful-pce], the PCE MUST send In other words, if the incremental state synchronization capability
back a PCErr with Error-Type 20 Error-Value TBD (suggested value - 2) is not advertised by the peers, based on the LSP database version
'LSP Database version mismatch', and close the PCEP session. number match either the state synchronization is skipped or a full
state synchronization is performed. If the PCC attempts to skip
state synchronization, by setting the SYNC Flag to 0 and PLSP-ID to a
non-zero value on the first LSP State Report from the PCC as per
[I-D.ietf-pce-stateful-pce], the PCE MUST send back a PCErr with
Error-Type 20 Error-Value TBD2 (suggested value - 2) 'LSP Database
version mismatch', and close the PCEP session.
If state synchronization is required, then prior to completing the If state synchronization is required, then prior to completing the
initialization phase, the PCE MUST mark any LSPs in the LSP database initialization phase, the PCE MUST mark any LSPs in the LSP database
that were previously reported by the PCC as stale. When the PCC that were previously reported by the PCC as stale. When the PCC
reports an LSP during state synchronization, if the LSP already reports an LSP during state synchronization, if the LSP already
exists in the LSP database, the PCE MUST update the LSP database and exists in the LSP database, the PCE MUST update the LSP database and
clear the stale marker from the LSP. When it has finished state clear the stale marker from the LSP. When it has finished state
synchronization, the PCC MUST immediately send an end of synchronization, the PCC MUST immediately send an end of
synchronization marker. The end of synchronization marker is a Path synchronization marker. The end of synchronization marker is a Path
Computation State Report (PCRpt) message with an LSP object Computation State Report (PCRpt) message with an LSP object
skipping to change at page 9, line 29 skipping to change at page 9, line 29
|------PCRpt,SYNC=0----->| (Regular |------PCRpt,SYNC=0----->| (Regular
| | LSP State Report) | | LSP State Report)
|------PCRpt,SYNC=0----->| (Regular |------PCRpt,SYNC=0----->| (Regular
| | LSP State Report) | | LSP State Report)
|------PCRpt,SYNC=0----->| |------PCRpt,SYNC=0----->|
| | | |
Figure 3: State Synchronization Skipped, no LSP-DB-VERSION TLVs sent Figure 3: State Synchronization Skipped, no LSP-DB-VERSION TLVs sent
from PCC from PCC
3.2.1. IP Address change during session re-establishment
There could be a case during PCEP session re-establishment when the
PCC's or PCE's IP address can change. This includes, but is not
limited to, the following cases:
o A PCC could use a physical interface IP address to connect to the
PCE. In this case, if the line card that the PCC connects from
changes, then the PCEP session goes down and comes back up again,
with a different IP address associated with a new line card.
o The PCC or PCE may move in the network, either physically or
logically, which may cause its IP address to change. For example,
the PCE may be deployed as a virtual network function (VNF) and
another virtualized instance of the PCE may be populated with the
original PCE instance's state, but be given a different IP
address.
To ensure that a PCEP peer can recognize a previously connected peer,
each PCEP peer includes the SPEAKER-ENTITY-ID TLV described in
Section 3.3.2, in the OPEN message.
This TLV is used during the state synchronization procedure to
identify the PCEP session as a re-establishment of a previous session
that went down. Then state synchronization optimizations such as
state sync avoidance can be applied to this session. Note that this
usage is only applicable within the State Timeout Interval
[I-D.ietf-pce-stateful-pce]. After the State Timeout Interval
expires, all state associated with the PCEP session is removed, which
includes the SPEAKER-ENTITY-ID received. Note that the PCEP session
initialization [RFC5440] procedure remains unchanged.
3.3. PCEP Extensions 3.3. PCEP Extensions
A new INCLUDE-DB-VERSION (S) bit is added in the stateful A new INCLUDE-DB-VERSION (S) bit is added in the stateful
capabilities TLV (see Section 7 for details). capabilities TLV (see Section 7 for details).
3.3.1. LSP State Database Version Number TLV 3.3.1. LSP State Database Version Number TLV
The LSP State Database Version Number (LSP-DB-VERSION) TLV is an The LSP State Database Version Number (LSP-DB-VERSION) TLV is an
optional TLV that MAY be included in the OPEN object and the LSP optional TLV that MAY be included in the OPEN object and the LSP
object. object.
This TLV is included in the LSP object in the PCRpt message to
indicate the LSP DB version at the PCC. This TLV SHOULD NOT be
included in other PCEP messages (PCUpd, PcReq, PCRep) and MUST be
ignored if received.
The format of the LSP-DB-VERSION TLV is shown in the following The format of the LSP-DB-VERSION TLV is shown in the following
figure: figure:
0 1 2 3 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 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=8 | | Type=TBD5 | Length=8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP State DB Version Number | | LSP State DB Version Number |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: LSP-DB-VERSION TLV format Figure 4: LSP-DB-VERSION TLV format
The type of the TLV is TBD and it has a fixed length of 8 octets. The type of the TLV is TBD5 and it has a fixed length of 8 octets.
The value contains a 64-bit unsigned integer, representing the LSP The value contains a 64-bit unsigned integer, carried in network byte
State DB Version Number. order, representing the LSP State DB Version Number.
3.3.2. Speaker Entity Identifier TLV 3.3.2. Speaker Entity Identifier TLV
The Speaker Entity Identifier TLV (SPEAKER-ENTITY-ID) is an optional The Speaker Entity Identifier TLV (SPEAKER-ENTITY-ID) is an optional
TLV that MAY be included in the OPEN Object when a PCEP speaker TLV that MAY be included in the OPEN Object when a PCEP speaker
wishes to determine if state synchronization can be skipped when a wishes to determine if state synchronization can be skipped when a
PCEP session is restarted. It contains a unique identifier for the PCEP session is restarted. It contains a unique identifier for the
node that does not change during the lifetime of the PCEP speaker. node that does not change during the lifetime of the PCEP speaker.
It identifies the PCEP speaker to its peers even if the speaker's IP It identifies the PCEP speaker to its peers even if the speaker's IP
address is changed. address is changed.
skipping to change at page 11, line 8 skipping to change at page 11, line 31
identifier for future either way. In the latter case when PCEP identifier for future either way. In the latter case when PCEP
session is re-established, it would be correctly associated with session is re-established, it would be correctly associated with
speaker entity identifier and not be considered as an unknown peer. speaker entity identifier and not be considered as an unknown peer.
The format of the SPEAKER-ENTITY-ID TLV is shown in the following The format of the SPEAKER-ENTITY-ID TLV is shown in the following
figure: figure:
0 1 2 3 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 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 (variable) | | Type=TBD13 | Length (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Speaker Entity Identifier // // Speaker Entity Identifier //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: SPEAKER-ENTITY-ID TLV format Figure 5: SPEAKER-ENTITY-ID TLV format
The type of the TLV is TBD and it has a variable length, which MUST The type of the TLV is TBD13 and it has a variable length, which MUST
be greater than 0. The Value is padded to 4-octet alignment. The be greater than 0. The Value is padded to 4-octet alignment. The
padding is not included in the Length field. The value contains the padding is not included in the Length field. The value contains the
entity identifier of the speaker transmitting this TLV. This entity identifier of the speaker transmitting this TLV. This
identifier is required to be unique within its scope of visibility, identifier is required to be unique within its scope of visibility,
which is usually limited to a single domain. It MAY be configured by which is usually limited to a single domain. It MAY be configured by
the operator. Alternatively, it can be derived automatically from a the operator. Alternatively, it can be derived automatically from a
suitably-stable unique identifier, such as a MAC address, serial suitably-stable unique identifier, such as a MAC address, serial
number, Traffic Engineering Router ID, or similar. In the case of number, Traffic Engineering Router ID, or similar. In the case of
inter-domain connections, the speaker SHOULD prefix its usual inter-domain connections, the speaker SHOULD prefix its usual
identifier with the domain identifier of its residence, such as identifier with the domain identifier of its residence, such as
Autonomous System number, IGP area identifier, or similar. Autonomous System number, IGP area identifier, or similar to make
sure it remains unique.
The relationship between this identifier and entities in the Traffic The relationship between this identifier and entities in the Traffic
Engineering database is intentionally left undefined. Engineering database is intentionally left undefined.
From a manageability point of view, a PCE or PCC implementation From a manageability point of view, a PCE or PCC implementation
SHOULD allow the operator to configure this Speaker Entity SHOULD allow the operator to configure this Speaker Entity
Identifier. Identifier.
If a PCEP speaker receives the SPEAKER-ENTITY-ID on a new PCEP
session, that matches with an existing alive PCEP session, the PCEP
speaker MUST send a PCErr with Error-type 20 Error-value TBD7
(suggested value - 7) 'Received an invalid Speaker Entity
Identifier', and close the PCEP session.
4. Incremental State Synchronization 4. Incremental State Synchronization
[I-D.ietf-pce-stateful-pce] describes the LSP state synchronization [I-D.ietf-pce-stateful-pce] describes the LSP state synchronization
mechanism between PCCs and stateful PCEs. During the state mechanism between PCCs and stateful PCEs. During the state
synchronization, a PCC sends the information of all its LSPs (i.e., synchronization, a PCC sends the information of all its LSPs (i.e.,
the full LSP-DB) to the stateful PCE. In order to reduce the state the full LSP-DB) to the stateful PCE. In order to reduce the state
synchronization overhead when there is a small number of LSP state synchronization overhead when there is a small number of LSP state
change in the network between PCEP session restart, this section change in the network between PCEP session restart, this section
defines a mechanism for incremental (Delta) LSP Database (LSP-DB) defines a mechanism for incremental (Delta) LSP Database (LSP-DB)
synchronization. synchronization.
skipping to change at page 13, line 13 skipping to change at page 13, line 45
LSP changes can be small during the time when PCEP session is down. LSP changes can be small during the time when PCEP session is down.
An incremental (Delta) LSP Database (LSP-DB) state synchronization is An incremental (Delta) LSP Database (LSP-DB) state synchronization is
described in this section, where only the LSPs underwent state change described in this section, where only the LSPs underwent state change
are synchronized between the session restart. This may include are synchronized between the session restart. This may include
new/modified/deleted LSPs. new/modified/deleted LSPs.
4.2. Incremental Synchronization Procedure 4.2. Incremental Synchronization Procedure
[I-D.ietf-pce-stateful-pce] describes state synchronization and [I-D.ietf-pce-stateful-pce] describes state synchronization and
Section 3 describes state synchronization avoidance by using LSP-DB- Section 3 of this document, describes state synchronization avoidance
VERSION TLV in its OPEN object. This section extends this idea to by using LSP-DB-VERSION TLV in its OPEN object. This section extends
only synchronize the delta (changes) in case of version mismatch. this idea to only synchronize the delta (changes) in case of version
mismatch.
If both PCEP speakers include the LSP-DB-VERSION TLV in the OPEN If both PCEP speakers include the LSP-DB-VERSION TLV in the OPEN
object and the LSP-DB-VERSION TLV values match, the PCC MAY skip object and the LSP-DB-VERSION TLV values match, the PCC MAY skip
state synchronization. Otherwise, the PCC MUST perform state state synchronization. Otherwise, the PCC MUST perform state
synchronization. Incremental State synchronization capability is synchronization. Incremental State synchronization capability is
advertised on a PCEP session during session startup using the DELTA- advertised on a PCEP session during session startup using the DELTA-
LSP-SYNC-CAPABILITY (D) bit in the capabilities TLV (see Section 7). LSP-SYNC-CAPABILITY (D) bit in the capabilities TLV (see Section 7).
Instead of dumping full LSP-DB to the stateful PCE again, the PCC Instead of dumping full LSP-DB to the stateful PCE again, the PCC
synchronizes the delta (changes) as described in Figure 7 when D flag synchronizes the delta (changes) as described in Figure 7 when D flag
and S flag is set to 1 by both PCC and PCE. Other combinations of D and S flag is set to 1 by both PCC and PCE. Other combinations of D
and S flags setting by PCC and PCE result in full LSP-DB and S flags setting by PCC and PCE result in full LSP-DB
synchronization procedure as described in synchronization procedure as described in
[I-D.ietf-pce-stateful-pce]. The PCC MAY force a full LSP DB [I-D.ietf-pce-stateful-pce]. By setting the D flag to zero in the
synchronization by setting the D flag to zero in the OPEN message. OPEN message, a PCEP speaker can skip the incremental synchronization
optimization, resulting in a full LSP DB synchronization.
+-+-+ +-+-+ +-+-+ +-+-+
|PCC| |PCE| |PCC| |PCE|
+-+-+ +-+-+ +-+-+ +-+-+
| | | |
|--Open--, | |--Open--, |
| DBv=46 \ ,---Open--| | DBv=46 \ ,---Open--|
| S=1 \ / DBv=42 | | S=1 \ / DBv=42 |
| D=1 \/ S=1 | | D=1 \/ S=1 |
| /\ D=1 | | /\ D=1 |
skipping to change at page 14, line 41 skipping to change at page 15, line 41
|--PCRpt,DBv=49,SYNC=0-->| |--PCRpt,DBv=49,SYNC=0-->|
| | | |
Figure 7: Incremental Synchronization Procedure Figure 7: Incremental Synchronization Procedure
As per Section 3, the LSP State Database Version Number is As per Section 3, the LSP State Database Version Number is
incremented each time a change is made to the PCC's local LSP State incremented each time a change is made to the PCC's local LSP State
Database. Each LSP is associated with the DB version at the time of Database. Each LSP is associated with the DB version at the time of
its state change. This is needed to determine which LSP and what its state change. This is needed to determine which LSP and what
information needs to be synchronized in incremental state information needs to be synchronized in incremental state
synchronization. synchronization. The incremental state sync is done from the last
LSP DB version received by the PCE to the latest DB version at the
PCC. Note that the LSP State Database Version Number can wrap
around, and in which case the incremental state sync would also wrap
till the latest DB version number at the PCC.
It is not necessary for a PCC to store a complete history of LSP In order to carry out incremental state synchronization, it is not
Database change, but rather remember the LSP state changes (including necessary for a PCC to store a complete history of LSP Database
LSP modification, setup and deletion) that happened between the PCEP change for all time, but remember the LSP state changes (including
session(s) restart in order to carry out incremental state LSP modification, setup and deletion), that the PCE did not get to
synchronization. After the synchronization procedure finishes, the process during the session down. Note that, a PCC would be unaware
PCC can dump this history information. In the example shown in that a particular LSP report has been processed by the PCE before the
session to PCE went down. So a PCC implementation MAY choose to
store the LSP State Database Version Number with each LSP at the time
its status changed, so that when a session is re-established an
incremental synchronization can be attempted based on the PCE's last
LSP State Database Version Number. For an LSP that is deleted at the
PCC, the PCC implementation would need to remember the deleted LSP in
some way to make sure this could be reported as part of incremental
synchronization later. The PCC would discard this information based
on a local policy, or when it determines that this information is no
longer needed with sufficient confidence. In the example shown in
Figure 7, the PCC needs to store the LSP state changes that happened Figure 7, the PCC needs to store the LSP state changes that happened
between DB Version 43 to 46 and synchronizes these changes only when between DB Version 43 to 46 and synchronizes these changes, when
performing incremental LSP state update. So a PCC needs to remember performing incremental LSP state update.
at least the LSP state changes that happened after an existing PCEP
session with a stateful PCE goes down to have any chance of doing
incremental synchronisation when the session is re-established.
If a PCC finds out it does not have sufficient information to If a PCC finds out it does not have sufficient information to
complete incremental synchronisation after advertising incremental complete incremental synchronization after advertising incremental
LSP state synchronization capability, it MUST send a PCErr with LSP state synchronization capability, it MUST send a PCErr with
Error-Type 20 and Error-Value 5 'A PCC indicates to a PCE that it can Error-Type 20 and Error-Value 5 'A PCC indicates to a PCE that it can
not complete the state synchronization' (defined in not complete the state synchronization' (defined in
[I-D.ietf-pce-stateful-pce]) and terminate the session. The PCC [I-D.ietf-pce-stateful-pce]) and terminate the session. The PCC
SHOULD re-establish the session with the D bit set to 0 in the OPEN SHOULD re-establish the session with the D bit set to 0 in the OPEN
message. message.
The other procedures and error checks remain unchanged from the full The other procedures and error checks remain unchanged from the full
state synchronization ([I-D.ietf-pce-stateful-pce]). state synchronization ([I-D.ietf-pce-stateful-pce]).
skipping to change at page 15, line 48 skipping to change at page 17, line 13
different scenarios and for different purposes. different scenarios and for different purposes.
5.2. PCE-triggered Initial State Synchronization Procedure 5.2. PCE-triggered Initial State Synchronization Procedure
Support of PCE-triggered initial state synchronization is advertised Support of PCE-triggered initial state synchronization is advertised
during session startup using the TRIGGERED-INITIAL-SYNC (F) bit in during session startup using the TRIGGERED-INITIAL-SYNC (F) bit in
the STATEFUL-PCE-CAPABILITY TLV (see Section 7). the STATEFUL-PCE-CAPABILITY TLV (see Section 7).
In order to allow a stateful PCE to control the LSP-DB In order to allow a stateful PCE to control the LSP-DB
synchronization after establishing a PCEP session, both PCEP speakers synchronization after establishing a PCEP session, both PCEP speakers
MUST set F bit to 1 in the OPEN message. If the TRIGGERED-INITIAL- MUST set F bit to 1 in the OPEN message. If the LSP-DB-VERSION TLV
SYNC capability is not advertised by a PCE and the PCC receives a is included by both PCEP speakers and the TLV value matches, the
PCUpd with the SYNC flag set to 1, it MUST send a PCErr with the SRP- state synchronization can be skipped as described in Section 3.2. If
ID-number of the PCUpd, Error-Type 20 and Error-Value TBD (suggested the TLV is not included or the LSP-DB Version is mis-matched, the PCE
can trigger the state synchronization process by sending a PCUpd
message with PLSP-ID = 0 and SYNC = 1. The PCUpd message SHOULD
include an empty ERO (with no ERO sub-object and object length of 4)
as its intended path and SHOULD NOT include the optional objects for
its attributes for any parameter update. The PCC MUST ignore such an
update when the SYNC flag is set. If the TRIGGERED-INITIAL-SYNC
capability is not advertised by a PCE and the PCC receives a PCUpd
with the SYNC flag set to 1, the PCC MUST send a PCErr with the SRP-
ID-number of the PCUpd, Error-Type 20 and Error-Value TBD4 (suggested
value - 4) 'Attempt to trigger synchronization when the TRIGGERED- value - 4) 'Attempt to trigger synchronization when the TRIGGERED-
SYNC capability has not been advertised' (see Section 8.1). If the SYNC capability has not been advertised' (see Section 8.1). If the
LSP-DB Version is mis-matched, it can send a PCUpd message with PLSP- TRIGGERED-INITIAL-SYNC capability is advertised by a PCE and the PCC,
ID = 0 and SYNC = 1 in order to trigger the LSP-DB synchronization the PCC MUST NOT trigger state synchronization on its own. If the
process. The PCUpd message MUST include an empty ERO as its intended PCE receives a PCRpt message before the PCE has triggered the state
path and SHOULD NOT include the optional objects for its attributes. synchronization, the PCE MUST send a PCErr with Error-Type 20 and
Error-Value TBD3 (suggested value - 3) 'Attempt to trigger
synchronization before PCE trigger' (see Section 8.1).
In this way, the PCE can control the sequence of LSP synchronization In this way, the PCE can control the sequence of LSP synchronization
among all the PCCs that are re-establishing PCEP sessions with it. among all the PCCs that are re-establishing PCEP sessions with it.
When the capability of PCE control is enabled, only after a PCC When the capability of PCE control is enabled, only after a PCC
receives this message, it will start sending information to the PCE. receives this message, it will start sending information to the PCE.
The PCC SHOULD NOT send PCRpt messages to the stateful PCE before it This PCE-triggering capability can be applied to both full and
triggers the State Synchronization. This PCE-triggering capability incremental state synchronization. If applied to the latter, the
can be applied to both full and incremental state synchronization. PCCs only send information that PCE does not possess, which is
If applied to the later, the PCCs only send information that PCE does inferred from the LSP-DB version information exchanged in the OPEN
not possess, which is inferred from the LSP-DB version information message (see Section 4.2 for detailed procedure).
exchanged in the OPEN message (see Section 4.2 for detailed
procedure).
Once the initial state synchronization is triggered by the PCE, the Once the initial state synchronization is triggered by the PCE, the
procedures and error checks remain unchanged from the full state procedures and error checks remain unchanged
synchronization ([I-D.ietf-pce-stateful-pce]). ([I-D.ietf-pce-stateful-pce]).
If a PCC implementation that does not implement this extension should
not receive a PCUpd message to trigger state synchronization as per
the capability advertisement, but if it were to receive it, it will
behave as per [I-D.ietf-pce-stateful-pce].
6. PCE-triggered Re-synchronization 6. PCE-triggered Re-synchronization
6.1. Motivation 6.1. Motivation
The accuracy of the computations performed by the PCE is tied to the The accuracy of the computations performed by the PCE is tied to the
accuracy of the view the PCE has on the state of the LSPs. accuracy of the view the PCE has on the state of the LSPs.
Therefore, it can be beneficial to be able to re-synchronize this Therefore, it can be beneficial to be able to re-synchronize this
state even after the session has been established. The PCE may use state even after the session has been established. The PCE may use
this approach to continuously sanity check its state against the this approach to continuously sanity check its state against the
network, or to recover from error conditions without having to tear network, or to recover from error conditions without having to tear
down sessions. down sessions.
6.2. PCE-triggered State Re-synchronization Procedure 6.2. PCE-triggered State Re-synchronization Procedure
Support of PCE-triggered state synchronization is advertised by both Support of PCE-triggered state re-synchronization is advertised by
PCEP speakers during session startup using the TRIGGERED-RESYNC (T) both PCEP speakers during session startup using the TRIGGERED-RESYNC
bit in the STATEFUL-PCE-CAPABILITY TLV (see Section 7). The PCE can (T) bit in the STATEFUL-PCE-CAPABILITY TLV (see Section 7). The PCE
choose to re-synchronize its entire LSP database or a single LSP. can choose to re-synchronize its entire LSP database or a single LSP.
To trigger re-synchronization for an LSP, the PCE MUST first mark the To trigger re-synchronization for an LSP, the PCE sends a Path
LSP as stale and then send a Path Computation State Update (PCUpd) Computation State Update (PCUpd) for the LSP, with the SYNC flag in
for it, with the SYNC flag in the LSP object set to 1. The PCE the LSP object set to 1. The PCE SHOULD NOT include any parameter
SHOULD NOT include any parameter updates for the LSP, and the PCC updates for the LSP, and the PCC MUST ignore such an update when the
SHOULD ignore such updates if the SYNC flag is set. The PCC MUST SYNC flag is set. The PCC MUST respond with a PCRpt message with the
respond with a PCRpt message with the LSP state, SYNC Flag set to 0 LSP state, SYNC Flag set to 0 and MUST include the SRP-ID-number of
and MUST include the SRP-ID-number of the PCUpd message that the PCUpd message that triggered the resynchronization. If the PCC
triggered the resynchronization. cannot find the LSP in its database, PCC MUST also set the R (remove)
flag [I-D.ietf-pce-stateful-pce] in the LSP object in the PCRpt
message.
The PCE can also trigger re-synchronization of the entire LSP The PCE can also trigger re-synchronization of the entire LSP
database. The PCE MUST first mark all LSPs in the LSP database that database. The PCE MUST first mark all LSPs in the LSP database that
were previously reported by the PCC as stale and then send a PCUpd were previously reported by the PCC as stale and then send a PCUpd
with an LSP object containing a PLSP-ID of 0 and with the SYNC flag with an LSP object containing a PLSP-ID of 0 and with the SYNC flag
set to 1. The PCUpd message MUST include an empty ERO as its set to 1. The PCUpd message MUST include an empty ERO (with no ERO
intended path and SHOULD NOT include the optional objects for its sub-object and object length of 4) as its intended path and SHOULD
attributes. This PCUpd message is the trigger for the PCC to enter NOT include the optional objects for its attributes for any parameter
the synchronization phase as described in [I-D.ietf-pce-stateful-pce] update. The PCC MUST ignore such update if the SYNC flag is set.
and start sending PCRpt messages. After the receipt of the end-of- This PCUpd message is the trigger for the PCC to enter the
synchronization phase as described in [I-D.ietf-pce-stateful-pce] and
start sending PCRpt messages. After the receipt of the end-of-
synchronization marker, the PCE will purge LSPs which were not synchronization marker, the PCE will purge LSPs which were not
refreshed. The SRP-ID-number of the PCUpd that triggered the re- refreshed. The SRP-ID-number of the PCUpd that triggered the re-
synchronization SHOULD be included in each of the PCRpt messages. synchronization SHOULD be included in each of the PCRpt messages. If
the PCC cannot re-synchronize the entire LSP database, the PCC MUST
respond with PCErr message with Error-type 20 Error-value 5 'cannot
complete the state synchronization' [I-D.ietf-pce-stateful-pce], and
MAY terminate the session. The PCE MUST remove the stale mark for
the LSP that were previously reported by the PCC. Based on the local
policy, the PCE MAY reattempt synchronization at a later time.
If the TRIGGERED-RESYNC capability is not advertised by a PCE and the If the TRIGGERED-RESYNC capability is not advertised by a PCE and the
PCC receives a PCUpd with the SYNC flag set to 1, it MUST send a PCC receives a PCUpd with the SYNC flag set to 1, it MUST send a
PCErr with the SRP-ID-number of the PCUpd, Error-Type 20 and Error- PCErr with the SRP-ID-number of the PCUpd, Error-Type 20 and Error-
Value TBD (suggested value - 4) 'Attempt to trigger synchronization Value TBD4 (suggested value - 4) 'Attempt to trigger synchronization
when the TRIGGERED-SYNC capability has not been advertised' (see when the TRIGGERED-SYNC capability has not been advertised' (see
Section 8.1). Section 8.1).
Once the state re-synchronization is triggered by the PCE, the Once the state re-synchronization is triggered by the PCE, the
procedures and error checks remain unchanged from the full state procedures and error checks remain unchanged from the full state
synchronization ([I-D.ietf-pce-stateful-pce]). This would also synchronization ([I-D.ietf-pce-stateful-pce]). This would also
include PCE triggering multiple state re-synchronization requests include PCE triggering multiple state re-synchronization requests
while synchronization is in progress. while synchronization is in progress.
If a PCC implementation that does not implement this extension should
not receive a PCUpd message to trigger re-synchronization as per the
capability advertisement, but if it were to receive it, it will
behave as per [I-D.ietf-pce-stateful-pce].
7. Advertising Support of Synchronization Optimizations 7. Advertising Support of Synchronization Optimizations
Support for each of the optimizations described in this document Support for each of the optimizations described in this document
requires advertising the corresponding capabilities during session requires advertising the corresponding capabilities during session
establishment time. establishment time.
New flags are defined for the STATEFUL-PCE-CAPABILITY TLV defined in The STATEFUL-PCE-CAPABILITY TLV is defined in
[I-D.ietf-pce-stateful-pce]. Its format is shown in the following [I-D.ietf-pce-stateful-pce]. This document defines following new
figure: flags in the STATEFUL-PCE-CAPABILITY TLV:
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 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |F|D|T|I|S|U|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: STATEFUL-PCE-CAPABILITY TLV Format
The value comprises a single field - Flags (32 bits):
U (LSP-UPDATE-CAPABILITY - 1 bit): defined in Bit Description
[I-D.ietf-pce-stateful-pce]. TBD9 (suggested value 30) S bit (INCLUDE-DB-VERSION)
TBD10 (suggested value 27) D bit (DELTA-LSP-SYNC-CAPABILITY)
TBD11 (suggested value 26) F bit (TRIGGERED-INITIAL-SYNC)
TBD12 (suggested value 28) T bit (TRIGGERED-RESYNC)
S (INCLUDE-DB-VERSION - 1 bit): if set to 1 by both PCEP Speakers, If the S (INCLUDE-DB-VERSION) bit is set to 1 by both PCEP Speakers,
the PCC will include the LSP-DB-VERSION TLV in each LSP Object. the PCC will include the LSP-DB-VERSION TLV in each LSP Object. See
See Section 3.2 for details. Section 3.2 for details.
I (LSP-INSTANTIATION-CAPABILITY - 1 bit): defined in If the D (DELTA-LSP-SYNC-CAPABILITY) bit is set to 1 by a PCEP
[I-D.ietf-pce-pce-initiated-lsp]. speaker, it indicates that the PCEP speaker allows incremental
(delta) state synchronization. See Section 4.2 for details.
T (TRIGGERED-RESYNC - 1 bit): if set to 1 by both PCEP Speakers, the If the F (TRIGGERED-INITIAL-SYNC) bit is set to 1 by both PCEP
PCE can trigger re-synchronization of LSPs at any point in the Speakers, the PCE SHOULD trigger initial (first) state
life of the session. See Section 6.2 for details. synchronization. See Section 5.2 for details.
D (DELTA-LSP-SYNC-CAPABILITY - 1 bit): if set to 1 by a PCEP If the T (TRIGGERED-RESYNC) bit is set to 1 by both PCEP Speakers,
speaker, it indicates that the PCEP speaker allows incremental the PCE can trigger re-synchronization of LSPs at any point in the
(delta) state synchronization. See Section 4.2 for details. life of the session. See Section 6.2 for details.
F (TRIGGERED-INITIAL-SYNC - 1 bit): if set to 1 by both PCEP See Section 8.3 for IANA allocations.
Speakers, the PCE SHOULD trigger initial (first) state
synchronization. See Section 5.2 for details.
8. IANA Considerations 8. IANA Considerations
This document requests IANA actions to allocate code points for the This document requests IANA actions to allocate code points for the
protocol elements defined in this document. protocol elements defined in this document.
8.1. PCEP-Error Object 8.1. PCEP-Error Object
IANA is requested to make the following allocation in the "PCEP-ERROR IANA is requested to make the following allocation in the "PCEP-ERROR
Object Error Types and Values" registry. Object Error Types and Values" registry.
Error-Type Meaning Reference Error-Type Meaning Reference
6 Mandatory Object missing [RFC5440] 6 Mandatory Object missing [RFC5440]
Error-Value= TBD(suggested This document Error-Value= TBD1(suggested This document
value 12): LSP-DB-VERSION TLV value 12): LSP-DB-VERSION TLV
missing missing
20 LSP State synchronization [I-D.ietf-pce-stateful-pce] 20 LSP State synchronization [I-D.ietf-pce-stateful-pce]
error error
Error-Value= TBD(suggested This document Error-Value= TBD2(suggested This document
value 2): LSP Database version value 2): LSP Database version
mismatch. mismatch.
Error-Value=TBD(suggested This document Error-Value=TBD3(suggested This document
value 3): The LSP-DB-VERSION value 3): Attempt to trigger
TLV Missing when state synchronization before PCE
synchronization avoidance is trigger.
enabled. Error-Value=TBD4(suggested This document
Error-Value=TBD(suggested This document
value 4): Attempt to trigger a value 4): Attempt to trigger a
synchronization when the synchronization when the
PCE triggered synchronization PCE triggered synchronization
capability has not been capability has not been
advertised. advertised.
Error-Value=TBD(suggested This document Error-Value=TBD6(suggested This document
value 6): No sufficient LSP value 6): Received an invalid
change information for LSP DB Version Number.
incremental LSP state Error-Value=TBD7(suggested This document
synchronization. value 7): Received an invalid
Error-Value=TBD(suggested This document Speaker Entity Identifier.
value 7): Received an invalid
LSP DB Version Number
8.2. PCEP TLV Type Indicators 8.2. PCEP TLV Type Indicators
IANA is requested to make the following allocation in the "PCEP TLV IANA is requested to make the following allocation in the "PCEP TLV
Type Indicators" registry. Type Indicators" registry.
Value Meaning Reference Value Meaning Reference
TBD(suggested value 23) LSP-DB-VERSION This document TBD5(suggested value 23) LSP-DB-VERSION This document
TBD(suggested value 24) SPEAKER-ENTITY-ID This document TBD13(suggested value 24) SPEAKER-ENTITY-ID This document
8.3. STATEFUL-PCE-CAPABILITY TLV 8.3. STATEFUL-PCE-CAPABILITY TLV
The STATEFUL-PCE-CAPABILITY TLV is defined in The STATEFUL-PCE-CAPABILITY TLV is defined in
[I-D.ietf-pce-stateful-pce] and a registry is requested to be [I-D.ietf-pce-stateful-pce] and a registry is requested to be
created to manage the flags in the TLV. IANA is requested to make created to manage the flags in the TLV. IANA is requested to make
the following allocation in the aforementioned registry. the following allocation in the aforementioned registry.
Bit Description Reference Bit Description Reference
TBD(suggested value 26) TRIGGERED-INITIAL-SYNC This document TBD11 (suggested value 26) TRIGGERED-INITIAL-SYNC This document
TBD(suggested value 27) DELTA-LSP-SYNC-CAPABILITY This document TBD10 (suggested value 27) DELTA-LSP-SYNC-CAPABILITY This document
TBD(suggested value 28) TRIGGERED-RESYNC This document TBD12 (suggested value 28) TRIGGERED-RESYNC This document
TBD(suggested value 30) INCLUDE-DB-VERSION This document TBD9 (suggested value 30) INCLUDE-DB-VERSION This document
9. Manageability Considerations 9. Manageability Considerations
All manageability requirements and considerations listed in [RFC5440] All manageability requirements and considerations listed in [RFC5440]
and [I-D.ietf-pce-stateful-pce] apply to PCEP protocol extensions and [I-D.ietf-pce-stateful-pce] apply to PCEP protocol extensions
defined in this document. In addition, requirements and defined in this document. In addition, requirements and
considerations listed in this section apply. considerations listed in this section apply.
9.1. Control of Function and Policy 9.1. Control of Function and Policy
A PCE or PCC implementation MUST allow configuring the state A PCE or PCC implementation MUST allow configuring the state
synchronization optimization capabilities as described in this synchronization optimization capabilities as described in this
document. The implementation SHOULD also allow the operator to document. The implementation SHOULD also allow the operator to
configure the Speaker Entity Identifier ( Section 3.3.2). configure the Speaker Entity Identifier ( Section 3.3.2). Further,
the operator SHOULD be to be allowed to trigger the re-
synchronization procedures as per Section 6.2.
9.2. Information and Data Models 9.2. Information and Data Models
An implementation SHOULD allow the operator to view the stateful An implementation SHOULD allow the operator to view the stateful
capabilities advertised by each peer, and the current synchronization capabilities advertised by each peer, and the current synchronization
status with each peer. To serve this purpose, the PCEP MIB module status with each peer. To serve this purpose, the PCEP YANG module
can be extended to include advertised stateful capabilities, and [I-D.ietf-pce-pcep-yang] can be extended to include advertised
synchronization status. stateful capabilities, and synchronization status.
9.3. Liveness Detection and Monitoring 9.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already detection and monitoring requirements in addition to those already
listed in [RFC5440]. listed in [RFC5440].
9.4. Verify Correct Operations 9.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in verification requirements in addition to those already listed in
[RFC5440] and [I-D.ietf-pce-stateful-pce]. [RFC5440] and [I-D.ietf-pce-stateful-pce].
9.5. Requirements On Other Protocols 9.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements Mechanisms defined in this document do not imply any new requirements
on other protocols. on other protocols.
9.6. Impact On Network Operations 9.6. Impact On Network Operations
Mechanisms defined in this document do not have any impact on network Mechanisms defined in [RFC5440] and [I-D.ietf-pce-stateful-pce] also
operations in addition to those already listed in [RFC5440] and apply to PCEP extensions defined in this document.
[I-D.ietf-pce-stateful-pce].
The state synchronization optimizations described in this document
can result in a reduction of the amount of data exchanged and the
time taken for a stateful PCE to be fully operational when a PCEP
session is re-established. The ability to trigger re-synchronization
by the PCE can be utilized by the operator to sanity check its state
and recover from any mismatch in state without tearing down the
session.
10. Security Considerations 10. Security Considerations
The security considerations listed in [I-D.ietf-pce-stateful-pce] The security considerations listed in [I-D.ietf-pce-stateful-pce]
apply to this document as well. However, because the protocol apply to this document as well. However, this document also
modifications outlined in this document allow the PCE to control introduces some new attack vectors. An attacker could spoof the
state (re)-synchronization timing and sequence, it also introduces a SPEAKER-ENTITY-ID and pretend to be another PCEP speaker. An
new attack vector: an attacker may flood the PCC with triggered re- attacker may flood the PCC with triggered re-synchronization request
synchronization request at a rate which exceeds the PCC's ability to at a rate which exceeds the PCC's ability to process them, either by
process them, either by spoofing messages or by compromising the PCE spoofing messages or by compromising the PCE itself. The PCC can
itself. The PCC is free to drop any trigger re-synchronization respond with PCErr message as described in Section 6.2 and terminate
request without additional processing. the session. Thus securing the PCEP session using mechanism like TCP
Authentication Option (TCP-AO) [RFC5925] or Transport Layer Security
(TLS) [I-D.ietf-pce-pceps] is RECOMMENDED.
11. Acknowledgements 11. Acknowledgments
We would like to thank Young Lee, Jonathan Hardwick, Sergio Belotti We would like to thank Young Lee, Sergio Belotti and Cyril Margaria
and Cyril Margaria for their comments and discussions. for their comments and discussions.
Thanks to Jonathan Hardwick for being the document shepherd and
provide comments and guidance.
Thanks to Tomonori Takeda for Routing Area Directorate review.
Thanks to Adrian Farrel for TSVART review and providing detailed
comments and suggestions.
12. Contributors 12. Contributors
Gang Xie Gang Xie
Huawei Technologies Huawei Technologies
F3-5-B R&D Center, Huawei Industrial Base, Bantian, Longgang District F3-5-B R&D Center, Huawei Industrial Base, Bantian, Longgang District
Shenzhen, Guangdong, 518129 Shenzhen, Guangdong, 518129
P.R. China P.R. China
Email: xiegang09@huawei.com Email: xiegang09@huawei.com
skipping to change at page 22, line 12 skipping to change at page 23, line 48
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440, Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009, DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>. <http://www.rfc-editor.org/info/rfc5440>.
13.2. Informative References 13.2. Informative References
[I-D.ietf-pce-pce-initiated-lsp] [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
Extensions for PCE-initiated LSP Setup in a Stateful PCE June 2010, <http://www.rfc-editor.org/info/rfc5925>.
Model", draft-ietf-pce-pce-initiated-lsp-07 (work in
progress), July 2016. [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
Stateful Path Computation Element (PCE)", RFC 8051,
DOI 10.17487/RFC8051, January 2017,
<http://www.rfc-editor.org/info/rfc8051>.
[I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and j.
jefftant@gmail.com, "A YANG Data Model for Path
Computation Element Communications Protocol (PCEP)",
draft-ietf-pce-pcep-yang-01 (work in progress), October
2016.
[I-D.ietf-pce-pceps]
Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure
Transport for PCEP", draft-ietf-pce-pceps-11 (work in
progress), January 2017.
Authors' Addresses Authors' Addresses
Edward Crabbe Edward Crabbe
Oracle Oracle
EMail: edward.crabbe@gmail.com EMail: edward.crabbe@gmail.com
Ina Minei Ina Minei
Google, Inc. Google, Inc.
 End of changes. 62 change blocks. 
227 lines changed or deleted 347 lines changed or added

This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/