draft-ietf-pce-stateful-hpce-07.txt   draft-ietf-pce-stateful-hpce-08.txt 
PCE Working Group D. Dhody PCE Working Group D. Dhody
Internet-Draft Y. Lee Internet-Draft Y. Lee
Intended status: Informational Huawei Technologies Intended status: Informational Huawei Technologies
Expires: October 26, 2019 D. Ceccarelli Expires: December 7, 2019 D. Ceccarelli
Ericsson Ericsson
J. Shin J. Shin
SK Telecom SK Telecom
D. King D. King
Lancaster University Lancaster University
O. Gonzalez de Dios O. Gonzalez de Dios
Telefonica I+D Telefonica I+D
April 24, 2019 June 6, 2019
Hierarchical Stateful Path Computation Element (PCE). Hierarchical Stateful Path Computation Element (PCE).
draft-ietf-pce-stateful-hpce-07 draft-ietf-pce-stateful-hpce-08
Abstract Abstract
A Stateful Path Computation Element (PCE) maintains information on A Stateful Path Computation Element (PCE) maintains information on
the current network state, including: computed Label Switched Path the current network state, including: computed Label Switched Path
(LSPs), reserved resources within the network, and pending path (LSPs), reserved resources within the network, and pending path
computation requests. This information may then be considered when computation requests. This information may then be considered when
computing new traffic engineered LSPs, and for associated computing new traffic engineered LSPs, and for associated
and dependent LSPs, received from Path Computation Clients (PCCs). and dependent LSPs, received from Path Computation Clients (PCCs).
Initialize the result of path computation from PCE is also helpful
for the PCC to gracefully establish the computed LSP.
The Hierarchical Path Computation Element (H-PCE) architecture, The Hierarchical Path Computation Element (H-PCE) architecture,
provides an architecture to allow the optimum sequence of provides an architecture to allow the optimum sequence of
inter-connected domains to be selected, and network policy to be inter-connected domains to be selected, and network policy to be
applied if applicable, via the use of a hierarchical relationship applied if applicable, via the use of a hierarchical relationship
between PCEs. between PCEs.
Combining the capabilities of Stateful PCE and the Hierarchical PCE Combining the capabilities of Stateful PCE and the Hierarchical PCE
would be advantageous. This document describes general considerations would be advantageous. This document describes general considerations
and use cases for the deployment of Stateful PCE(s) using the and use cases for the deployment of Stateful, and not Stateless, PCEs
Hierarchical PCE architecture. using the Hierarchical PCE architecture.
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
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 7, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 1.1. Use-cases and Applicability of Hierarchical Stateful PCE .4
1.2. Use-cases and Applicability of Hierarchical Stateful PCE . 5 1.1.1 Applicability to ACTN . . . . . . . . . . . . . . . . .5
1.2.1 Applicability to ACTN . . . . . . . . . . . . . . . . . 6 1.1.2 End-to-End Contiguous LSP . . . . . . . . . . . . . . .5
1.2.2 End-to-End Contiguous LSP . . . . . . . . . . . . . . . 6 1.1.3 Applicability of a Stateful P-PCE . . . . . . . . . . .6
1.2.3 Applicability of a Stateful P-PCE . . . . . . . . . . . 7 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . .6
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Hierarchical Stateful PCE . . . . . . . . . . . . . . . . . .7
3. Hierarchical Stateful PCE . . . . . . . . . . . . . . . . . . 7 3.1. Passive Operations . . . . . . . . . . . . . . . . . . . .9
3.1. Passive Operations . . . . . . . . . . . . . . . . . . . . 9 3.2. Active Operations . . . . . . . . . . . . . . . . . . . .10
3.2. Active Operations . . . . . . . . . . . . . . . . . . . . 11 3.3. PCE Initiation of LSPs . . . . . . . . . . . . . . . . . .11
3.3. PCE Initiation Operation . . . . . . . . . . . . . . . . . 12 3.3.1. Per Domain Stitched LSP . . . . . . . . . . . . . . .12
3.3.1. Per Domain Stitched LSP . . . . . . . . . . . . . . . 13 4. Security Considerations . . . . . . . . . . . . . . . . . . .14
4. Other Considerations . . . . . . . . . . . . . . . . . . . . . 15 5. Manageability Considerations . . . . . . . . . . . . . . . . .15
4.1. Applicability to Inter-Layer . . . . . . . . . . . . . . . 15 5.1. Control of Function and Policy . . . . . . . . . . . . . .15
5. Other Considerations . . . . . . . . . . . . . . . . . . . . . 16 5.2. Information and Data Models . . . . . . . . . . . . . . .15
5.1. Scalability Considerations . . . . . . . . . . . . . . . . 16 5.3. Liveness Detection and Monitoring . . . . . . . . . . . .15
5.2. Confidentiality . . . . . . . . . . . . . . . . . . . . . 16 5.4. Verify Correct Operations . . . . . . . . . . . . . . . .15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 5.5. Requirements On Other Protocols . . . . . . . . . . . . .15
7. Manageability Considerations . . . . . . . . . . . . . . . . . 17 5.6. Impact On Network Operations . . . . . . . . . . . . . . .16
7.1. Control of Function and Policy . . . . . . . . . . . . . . 17 6. Other Considerations . . . . . . . . . . . . . . . . . . . . .16
7.2. Information and Data Models . . . . . . . . . . . . . . . 17 6.1. Applicability to Inter-Layer Traffic Engineering . . . . .16
7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 17 6.2. Scalability Considerations . . . . . . . . . . . . . . . .17
7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 17 6.3. Confidentiality . . . . . . . . . . . . . . . . . . . . .17
7.5. Requirements On Other Protocols . . . . . . . . . . . . . 18 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . .18
7.6. Impact On Network Operations . . . . . . . . . . . . . . . 18 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .18
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 9. References . . . . . . . . . . . . . . . . . . . . . . . . .18
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 9.1. Normative References . . . . . . . . . . . . . . . . . . .18
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 9.2. Informative References . . . . . . . . . . . . . . . . . .19
10.1. Normative References . . . . . . . . . . . . . . . . . . 18 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . .21
10.2. Informative References . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .21
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
The Path Computation Element communication Protocol (PCEP) provides The Path Computation Element communication Protocol (PCEP) [RFC5440]
mechanisms for Path Computation Elements (PCEs) to perform path provides mechanisms for Path Computation Elements (PCEs) to perform
computations in response to Path Computation Clients' (PCCs) path computations in response to Path Computation Clients' (PCCs)
requests. requests.
A stateful PCE is capable of considering, for the purposes of A stateful PCE is capable of considering, for the purposes of
path computation, not only the network state in terms of links and path computation, not only the network state in terms of links and
nodes (referred to as the Traffic Engineering Database or TED) but nodes (referred to as the Traffic Engineering Database or TED) but
also the status of active services (previously computed paths, also the status of active services (previously computed paths,
and currently reserved resources, stored in the Label Switched and currently reserved resources, stored in the Label Switched
Paths Database (LSP-DB). Paths Database (LSP-DB).
[RFC8051] describes general considerations for a stateful PCE [RFC8051] describes general considerations for a stateful PCE
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development. [RFC6805] describes a Hierarchical PCE (H-PCE) development. [RFC6805] describes a Hierarchical PCE (H-PCE)
architecture which can be used for computing end-to-end paths for architecture which can be used for computing end-to-end paths for
inter-domain MPLS Traffic Engineering (TE) and GMPLS Label Switched inter-domain MPLS Traffic Engineering (TE) and GMPLS Label Switched
Paths (LSPs). Within the Hierarchical PCE (H-PCE) architecture Paths (LSPs). Within the Hierarchical PCE (H-PCE) architecture
[RFC6805], the Parent PCE (P-PCE) is used to compute a multi-domain [RFC6805], the Parent PCE (P-PCE) is used to compute a multi-domain
path based on the domain connectivity information. A Child PCE path based on the domain connectivity information. A Child PCE
(C-PCE) may be responsible for a single domain or multiple domains, (C-PCE) may be responsible for a single domain or multiple domains,
it is used to compute the intra-domain path based on its domain it is used to compute the intra-domain path based on its domain
topology information. topology information.
This document presents general considerations for stateful PCE(s) in This document presents general considerations for stateful PCEs, and
hierarchical PCE architecture. In particular, the behavior changes not Stateless, in the hierarchical PCE architecture. In particular,
and additions to the existing stateful PCE mechanisms (including PCE- the behavior changes and additions to the existing stateful PCE
initiated LSP setup and active PCE usage) in the context of networks mechanisms (including PCE-initiated LSP setup and active PCE usage)
using the H-PCE architecture. in the context of networks using the H-PCE architecture.
The initial section of the document focuses on end to end (E2E)
inter-domain TE LSP. Section 3.3.1 describe the operations for the
Per Domain LSP that could be stitched.
1.1. Requirements Language In this document, Sections 3.1 and 3.2 focus on end to end (E2E)
inter-domain TE LSP. Section 3.3.1 describes the operations for
stitching Per Domain LSPs.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", Deployment of stateless H-PCE Architecture
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2. Use-cases and Applicability of Hierarchical Stateful PCE 1.1. Use-cases and Applicability of Hierarchical Stateful PCE
As per [RFC6805], in the hierarchical PCE architecture, a P-PCE As per [RFC6805], in the hierarchical PCE architecture, a P-PCE
maintains a domain topology map that contains the child domains and maintains a domain topology map that contains the child domains and
their interconnections. Usually, the P-PCE has no information about their interconnections. Usually, the P-PCE has no information about
the content of the child domains. But if the PCE is applied to the the content of the child domains. But if the PCE is applied to the
Abstraction and Control of TE Networks (ACTN) [RFC8453] as described Abstraction and Control of TE Networks (ACTN) [RFC8453] as described
in [I-D.ietf-pce-applicability-actn], the Provisioning Network in [I-D.ietf-pce-applicability-actn], the Provisioning Network
Controller (PNC) can provide an abstract topology to the Multi-Domain Controller (PNC) can provide an abstract topology to the Multi-Domain
Service Coordinator (MDSC). Thus the P-PCE in MDSC could be aware of Service Coordinator (MDSC). Thus the P-PCE in MDSC could be aware of
topology information in much more detail than just the domain topology information in much more detail than just the domain
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measurement probe) could also be a trigger at the P-PCE. Any such measurement probe) could also be a trigger at the P-PCE. Any such
update would require an inter-domain path recomputation as described update would require an inter-domain path recomputation as described
in [RFC6805]. in [RFC6805].
The inter-domain LSP could be set up using the end-to-end signaling The inter-domain LSP could be set up using the end-to-end signaling
as described in [RFC6805]. Additionally a per-domain stitched LSP as described in [RFC6805]. Additionally a per-domain stitched LSP
model is also applicable in a P-PCE initiation model. Section 3.1, model is also applicable in a P-PCE initiation model. Section 3.1,
Section 3.2, and Section 3.3 describe the end-to-end Contiguous LSP Section 3.2, and Section 3.3 describe the end-to-end Contiguous LSP
setup, whereas Section 3.3.1 describe the per-domain stitching. setup, whereas Section 3.3.1 describe the per-domain stitching.
1.2.1 Applicability to ACTN 1.1.1 Applicability to ACTN
[RFC8453] describes the framework for ACTN, where each PNC is [RFC8453] describes a framework for the Abstraction and Control of TE
equivalent to a C-PCE, and the P-PCE is the MDSC. In this case the Networks (ACTN), where each Provisioning Network Controller (PNC) is
P-PCE (MDSC) receives the request for inter-domain path setup as part equivalent to a C-PCE, and the P-PCE is the Multi-Domain Service
of the Virtual Network (VN) operations. The per-domain stitched LSP Coordinator (MDSC). The Per Domain stitched LSP as per the
for a P-PCE initiated model is well suited for ACTN. This is Hierarchical PCE architecture described in Section 3.3.1 and Section
described in Section 3.3.1 and Section 4.1 of this document. 4.1 is well suited for ACTN deployments.
[I-D.ietf-pce-applicability-actn] examines the applicability of PCE [I-D.ietf-pce-applicability-actn] examines the applicability of PCE
to the ACTN framework. To support the function of multi domain to the ACTN framework. To support the function of multi domain
coordination via hierarchy, the hierarchy of stateful PCEs play a coordination via hierarchy, the hierarchy of stateful PCEs play a
crucial role. crucial role.
In the ACTN framework, the Customer Network Controller (CNC) can In the ACTN framework, a Customer Network Controller (CNC) can
request the MDSC to check if there is a possibility to meet VN request the MDSC to check whether there is a possibility to meet
requirements (before requesting for VN provisioning). The H-PCE Virtual Network (VN) requirements before requesting for the VN to be
architecture as described in [RFC6805] can support VN compute provisioned. The H-PCE architecture as described in [RFC6805] can
function via the use of Path Computation Request (PCReq) and Path support this function using PCReq and PCRep messages between the
Computation Reply (PCRep) messages between the P-PCE and C-PCEs. When P-PCE and C-PCEs. When the CNC requests for VN provisioning, the
the CNC requests for VN provisioning, the MDSC decompose this request MDSC decompose this request into multiple inter-domain LSP
into multiple inter-domain LSP provisioning requests, which might be provisioning requests, which might be further decomposed to
further decomposed to per-domain path segments. This is described in per-domain path segments. This is described in Section 3.3.1. The
Section 3.3.1. The MDSC uses the LSP Initiate Request (PCInitiate) MDSC uses the LSP Initiate Request (PCInitiate) message from the
message from the P-PCE towards the C-PCE, and the C-PCE reports the P-PCE towards the C-PCE, and the C-PCE reports the state back to the
state back to the P-PCE via a Path Computation State Report (PCRpt) P-PCE via a Path Computation State Report (PCRpt) message. The P-PCE
message. The P-PCE could make changes to the LSP via the use of a could make changes to the LSP via the use of a Path Computation
Path Computation Update Request (PCUpd) message. Update Request (PCUpd) message.
In this case, the P-PCE (as MDSC) interacts with multiple C-PCEs (as In this case, the P-PCE (as MDSC) interacts with multiple C-PCEs (as
PNCs) along the inter-domain path of the LSP. PNCs) along the inter-domain path of the LSP.
1.2.2 End-to-End Contiguous LSP 1.1.2 End-to-End Contiguous LSP
Different signaling methods for inter-domain RSVP-TE signaling are Different signaling methods for inter-domain RSVP-TE signaling are
identified in [RFC4726]. Contiguous LSPs are achieved using the identified in [RFC4726]. Contiguous LSPs are achieved using the
procedures of [RFC3209] and [RFC3473] to create a single end-to-end procedures of [RFC3209] and [RFC3473] to create a single end-to-end
LSP that spans all domains. [RFC6805] describes the technique to LSP that spans all domains. [RFC6805] describes the technique to
establish the optimum path when the sequence of domains is not known establish the optimum path when the sequence of domains is not known
in advance. It shows how the PCE architecture can be extended to in advance. It shows how the PCE architecture can be extended to
allow the optimum sequence of domains to be selected, and the optimum allow the optimum sequence of domains to be selected, and the optimum
end-to-end path to be derived. end-to-end path to be derived.
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using the PCInitiate message for an E2E contiguous LSP. The P-PCE using the PCInitiate message for an E2E contiguous LSP. The P-PCE
would send the PCInitiate message to the Ingress domain C-PCE, which would send the PCInitiate message to the Ingress domain C-PCE, which
would further instruct the Ingress PCC. would further instruct the Ingress PCC.
In this document, for the Contiguous LSP, the above interactions are In this document, for the Contiguous LSP, the above interactions are
only between the ingress domain C-PCE and the P-PCE. The use of only between the ingress domain C-PCE and the P-PCE. The use of
stateful operations for an inter-domain LSP between the stateful operations for an inter-domain LSP between the
transit/egress domain C-PCEs towards the P-PCE is out of scope of transit/egress domain C-PCEs towards the P-PCE is out of scope of
this document. this document.
1.2.3 Applicability of a Stateful P-PCE 1.1.3 Applicability of a Stateful P-PCE
[RFC8051] describes general considerations for a stateful PCE [RFC8051] describes general considerations for a stateful PCE
deployment and examines its applicability and benefits, as well as deployment and examines its applicability and benefits, as well as
its challenges and limitations, through a number of use cases. These its challenges and limitations, through a number of use cases. These
are also applicable to the stateful P-PCE when used for the inter- are also applicable to the stateful P-PCE when used for the inter-
domain LSP path computation and setup. It should be noted that though domain LSP path computation and setup. It should be noted that though
the stateful P-PCE has limited direct visibility inside the child the stateful P-PCE has limited direct visibility inside the child
domain, it could still trigger re-optimization with the help of child domain, it could still trigger re-optimization with the help of child
PCEs based on LSP state changes, abstract topology changes, or some PCEs based on LSP state changes, abstract topology changes, or some
other external factors. other external factors.
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each C-PCE. each C-PCE.
Note that, in the scope of this document, both the C-PCEs and the P- Note that, in the scope of this document, both the C-PCEs and the P-
PCE are stateful in nature. PCE are stateful in nature.
[RFC8231] specifies new functions to support a stateful PCE. It also [RFC8231] specifies new functions to support a stateful PCE. It also
specifies that a function can be initiated either from a PCC towards 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). a PCE (C-E) or from a PCE towards a PCC (E-C).
This document extends these functions to support H-PCE Architecture This document extends these functions to support H-PCE Architecture
from a C-PCE towards a P-PCE (CE-PE) or from a P-PCE towards a C-PCE from a C-PCE towards P-PCE (EC-EP) or from a P-PCE towards C-PCE
(PE-CE). All PCE types herein (i.e., PE or CE) are assumed to be (EP-EC). All PCE types herein (i.e., EC-EP or EP-EC) are assumed to
'stateful PCE'. be "stateful PCE".
A number of interactions are expected in the Hierarchical Stateful A number of interactions are expected in the Hierarchical Stateful
PCE architecture, these include: PCE architecture, these include:
LSP State Report (CE-PE): a child stateful PCE sends an LSP state LSP State Report (EC-EP): a child stateful PCE sends an LSP state
report to a Parent Stateful PCE whenever the state of a LSP report to a Parent Stateful PCE whenever the state of a LSP
changes. changes.
LSP State Synchronization (CE-PE): after the session between the LSP State Synchronization (EC-EP): after the session between the
Child and Parent stateful PCEs is initialized, the P-PCE must Child and Parent stateful PCEs is initialized, the P-PCE must
learn the state of C-PCE's TE LSPs. learn the state of C-PCE's TE LSPs.
LSP Control Delegation (CE-PE,PE-CE): a C-PCE grants to the P-PCE LSP Control Delegation (EC-EP,EP-EC): a C-PCE grants to the P-PCE
the right to update LSP attributes on one or more LSPs; the C-PCE the right to update LSP attributes on one or more LSPs; the C-PCE
may withdraw the delegation or the P-PCE may give up the may withdraw the delegation or the P-PCE may give up the
delegation at any time. delegation at any time.
LSP Update Request (PE-CE): a stateful P-PCE requests modification LSP Update Request (EP-EC): a stateful P-PCE requests modification
of attributes on a C-PCE's TE LSP. of attributes on a C-PCE's TE LSP.
PCE LSP Initiation Request (PE-CE): a stateful P-PCE requests C-PCE PCE LSP Initiation Request (EP-EC): a stateful P-PCE requests C-PCE
to initiate a TE LSP. to initiate a TE LSP.
Note that this hierarchy is recursive and thus a Label Switching Note that this hierarchy is recursive and thus a Label Switching
Router (LSR), as a PCC could delegate the control to a PCE, which may Router (LSR), as a PCC could delegate the control to a PCE, which may
delegate to its parent, which may further delegate it to its parent delegate to its parent, which may further delegate it to its parent
(if it exist or needed). Similarly update operations could also be (if it exist or needed). Similarly update operations could also be
applied recursively. applied recursively.
[I-D.ietf-pce-hierarchy-extensions] defines the H-PCE capability TLV [I-D.ietf-pce-hierarchy-extensions] defines the H-PCE Capability TLV
that should be used in the OPEN message to advertise the H-PCE that is used in the OPEN message to advertise the H-PCE capability.
capability. [RFC8231] defines the stateful PCE capability TLV. The [RFC8231] defines the Stateful PCE Capability TLV used in the OPEN
presence of both TLVs represent the support for stateful H-PCE message to indicate stateful support. The presence of both TLVs in
operations as described in this document. an OPEN message indicates the support for stateful H-PCE operations
as described in this document.
[I-D.litkowski-pce-state-sync] describes the procedures to allow a Further consideration may be made for optional procedures for
stateful communication between PCEs for various use-cases. The stateful communication coordination between PCEs, including
procedures and extensions as described in Section 3 of procedures to minimise computational loops. The procedures described
[I-D.litkowski-pce-state-sync] are also applicable to Child and in [I-D.litkowski-pce-state-sync] facilitate stateful communication
Parent PCE communication. The SPEAKER-IDENTITY-TLV (defined in between PCEs for various use-cases. The procedures and extensions as
[RFC8232]) is included in the LSP object to identify the Ingress described in Section 3 of [I-D.litkowski-pce-state-sync] are also
(PCC). The PLSP-ID used in the forwarded PCRpt by the C-PCE to P-PCE applicable to Child and Parent PCE communication. The
is same as the original one used by the PCC. SPEAKER-IDENTITY-TLV (defined in [RFC8232]) is included in the LSP
object to identify the Ingress (PCC). The PLSP-ID used in the
forwarded PCRpt by the C-PCE to P-PCE is same as the original one
used by the PCC.
3.1. Passive Operations 3.1. Passive Operations
Procedures as described in [RFC6805] are applied, where the ingress Procedures as described in [RFC6805] are applied and where the
C-PCE sends a request to the P-PCE. The P-PCE selects a set of ingress C-PCE (Child PCE), triggers a path computation request for
candidate domain paths based on the domain topology and the state of the LER in the domain where the LSP originates, sends a request to
the inter-domain links. It then sends computation requests to the C- the P-PCE. The P-PCE selects a set of candidate domain paths based
PCEs responsible for each of the domains on the candidate domain on the domain topology and the state of the inter-domain links. It
paths. Each C-PCE computes a set of candidate path segments across then sends computation requests to the C-PCEs responsible for each
its domain and sends the results to the P-PCE. The P-PCE uses this of the domains on the candidate domain paths. Each C-PCE computes a
information to select path segments and concatenate them to derive set of candidate path segments across its domain and sends the
the optimal end-to-end inter-domain path. The end-to-end path is results to the P-PCE. The P-PCE uses this information to select path
then sent to the C-PCE that received the initial path request, and segments and concatenate them to derive the optimal end-to-end
this C-PCE passes the path on to the PCC that issued the original inter-domain path. The end-to-end path is then sent to the C-PCE
request. that received the initial path request, and this C-PCE passes the
path on to the PCC that issued the original request.
As per [RFC8231], PCC sends an LSP State Report carried on a PCRpt As per [RFC8231], PCC sends an LSP State Report carried on a PCRpt
message to the C-PCE, indicating the LSP's status. The C-PCE MAY message to the C-PCE, indicating the LSP's status. The C-PCE may
further propagate the State Report to the P-PCE. A local policy at further propagate the State Report to the P-PCE. A local policy at
C-PCE MAY dictate which LSPs to be reported to the P-PCE. The PCRpt C-PCE may dictate which LSPs to be reported to the P-PCE. The PCRpt
message is sent from C-PCE to P-PCE. message is sent from C-PCE to P-PCE.
State synchronization mechanism as described in [RFC8231] and State synchronization mechanism as described in [RFC8231] and
[RFC8232] are applicable to PCEP session between C-PCE and P-PCE as [RFC8232] are applicable to A PCEP session between C-PCE and P-PCE as
well. well.
Taking the sample hierarchical domain topology example from [RFC6805] We use the sample hierarchical domain topology example from [RFC6805]
as the reference topology for the entirety of this document. as the reference topology for the entirety of this document. It is
shown in Figure 1.
----------------------------------------------------------------- -----------------------------------------------------------------
| Domain 5 | | Domain 5 |
| ----- | | ----- |
| |PCE 5| | | |PCE 5| |
| ----- | | ----- |
| | | |
| ---------------- ---------------- ---------------- | | ---------------- ---------------- ---------------- |
| | Domain 1 | | Domain 2 | | Domain 3 | | | | Domain 1 | | Domain 2 | | Domain 3 | |
| | | | | | | | | | | | | | | |
skipping to change at page 10, line 51 skipping to change at page 10, line 9
| ---------------- | | ---------------- |
| | | |
----------------------------------------------------------------- -----------------------------------------------------------------
Figure 1: Sample Hierarchical Domain Topology Figure 1: Sample Hierarchical Domain Topology
Steps 1 to 11 are exactly as described in section 4.6.2 (Hierarchical Steps 1 to 11 are exactly as described in section 4.6.2 (Hierarchical
PCE End-to-End Path Computation Procedure) of [RFC6805], the PCE End-to-End Path Computation Procedure) of [RFC6805], the
following additional steps are added for stateful PCE: following additional steps are added for stateful PCE:
(1) The Ingress LSR initiates the setup of the LSP as per the path (A) The Ingress LSR initiates the setup of the LSP as per the path
and reports to the PCE1 the LSP status ("GOING-UP"). and reports to the PCE1 the LSP status ("GOING-UP").
(2) The PCE1 further reports the status of the LSP to the P-PCE (B) The PCE1 further reports the status of the LSP to the P-PCE
(PCE5). (PCE5).
(3) The Ingress LSR notifies the LSP state to PCE1 when the state is (C) The Ingress LSR notifies the LSP state to PCE1 when the state is
"UP". "UP".
(4) The PCE1 further reports the status of the LSP to the P-PCE (D) The PCE1 further reports the status of the LSP to the P-PCE
(PCE5). (PCE5).
The Ingress LSR could trigger path re-optimization by sending the The Ingress LSR could trigger path re-optimization by sending the
path computation request as described in [RFC6805], at this time it path computation request as described in [RFC6805], at this time it
can include the LSP object in the PCReq message as described in can include the LSP object in the PCReq message as described in
[RFC8231]. [RFC8231].
3.2. Active Operations 3.2. Active Operations
[RFC8231] describes the case of active stateful PCE. The active PCE [RFC8231] describes the case of active stateful PCE. The active PCE
skipping to change at page 11, line 37 skipping to change at page 10, line 44
The first is sent by the PCE to a Path Computation Client (PCC) for The first is sent by the PCE to a Path Computation Client (PCC) for
modifying LSP attributes. The PCC sends back a PCRpt to acknowledge modifying LSP attributes. The PCC sends back a PCRpt to acknowledge
the requested operation or report any change in LSP's state. the requested operation or report any change in LSP's state.
As per [RFC8051], Delegation is an operation to grant a PCE, As per [RFC8051], Delegation is an operation to grant a PCE,
temporary rights to modify a subset of LSP parameters on one or more temporary rights to modify a subset of LSP parameters on one or more
PCC's LSPs. The C-PCE may further choose to delegate to P-PCE based PCC's LSPs. The C-PCE may further choose to delegate to P-PCE based
on a local policy. The PCRpt message with "D" (delegate) flag is on a local policy. The PCRpt message with "D" (delegate) flag is
sent from C-PCE to P-PCE. sent from C-PCE to P-PCE.
To update an LSP, a PCE send to the PCC, an LSP Update Request using To update an LSP, a PCE sends an LSP Update Request to the PCC using
a PCUpd message. For LSP delegated to the P-PCE via the child PCE, a PCUpd message. For LSP delegated to the P-PCE via the child PCE,
the P-PCE can use the same PCUpd message to request change to the C- the P-PCE can use the same PCUpd message to request change to the C-
PCE (the Ingress domain PCE), the PCE further propagates the update PCE (the Ingress domain PCE), the PCE further propagates the update
request to the PCC. request to the PCC.
The P-PCE uses the same mechanism described in Section 3.1 to compute The P-PCE uses the same mechanism described in Section 3.1 to compute
the end to end path using PCReq and PCRep messages. the end to end path using PCReq and PCRep messages.
The following additional steps are also initially performed, for For active operations, the following steps are required when
active operations, again using the reference architecture described delegating the LSP, again using the reference architecture described
in Figure 1 (Sample Hierarchical Domain Topology). in Figure 1 (Sample Hierarchical Domain Topology).
(1) The Ingress LSR delegates the LSP to the PCE1 via PCRpt message (1) The Ingress LSR delegates the LSP to the PCE1 via PCRpt message
with D flag set. with D flag set.
(2) The PCE1 further delegates the LSP to the P-PCE (PCE5). (2) The PCE1 further delegates the LSP to the P-PCE (PCE5).
Steps 4 to 10 of section 4.6.2 of [RFC6805] are executed to determine Steps 4 to 10 of section 4.6.2 of [RFC6805] are executed to determine
the end to end path. the end to end path.
skipping to change at page 12, line 27 skipping to change at page 11, line 34
(6) The PCE1 further reports the status of the LSP to the P-PCE (6) The PCE1 further reports the status of the LSP to the P-PCE
(PCE5). (PCE5).
(7) The Ingress LSR notifies the LSP state to PCE1 when the state is (7) The Ingress LSR notifies the LSP state to PCE1 when the state is
"UP". "UP".
(8) The PCE1 further reports the status of the LSP to the P-PCE (8) The PCE1 further reports the status of the LSP to the P-PCE
(PCE5). (PCE5).
3.3. PCE Initiation Operation 3.3. PCE Initiation of LSPs
[RFC8281] describes the setup, maintenance and teardown of PCE- [RFC8281] describes the setup, maintenance and teardown of PCE-
initiated LSPs under the stateful PCE model, without the need for initiated LSPs under the stateful PCE model, without the need for
local configuration on the PCC, thus allowing for a dynamic network local configuration on the PCC, thus allowing for a dynamic network
that is centrally controlled and deployed. To instantiate or delete that is centrally controlled and deployed. To instantiate or delete
an LSP, the PCE sends the Path Computation LSP Initiate Request an LSP, the PCE sends the Path Computation LSP Initiate Request
(PCInitiate) message to the PCC. In case of inter-domain LSP in (PCInitiate) message to the PCC. In case of inter-domain LSP in
Hierarchical PCE architecture, the initiation operations can be Hierarchical PCE architecture, the initiation operations can be
carried out at the P-PCE. In which case after P-PCE finishes the E2E carried out at the P-PCE. In which case after P-PCE finishes the E2E
path computation, it can send the PCInitiate message to the C-PCE path computation, it can send the PCInitiate message to the C-PCE
skipping to change at page 13, line 47 skipping to change at page 13, line 4
Per Domain stitched LSP operation, again using the reference Per Domain stitched LSP operation, again using the reference
architecture described in Figure 1 (Sample Hierarchical Domain architecture described in Figure 1 (Sample Hierarchical Domain
Topology): Topology):
(1) The P-PCE (PCE5) is requested to initiate a LSP. (1) The P-PCE (PCE5) is requested to initiate a LSP.
Steps 4 to 10 of section 4.6.2 of [RFC6805] are executed to determine Steps 4 to 10 of section 4.6.2 of [RFC6805] are executed to determine
the end to end path, which are broken into per-domain LSPs say - the end to end path, which are broken into per-domain LSPs say -
o S-BN41 o S-BN41
o BN41-BN33 o BN41-BN33
o BN33-D o BN33-D
It should be noted that the P-PCE MAY use other mechanisms to It should be noted that the P-PCE may use other mechanisms to
determine the suitable per-domain LSPs (apart from [RFC6805]). determine the suitable per-domain LSPs (apart from [RFC6805]).
For LSP (BN33-D) For LSP (BN33-D)
(2) The P-PCE (PCE5) sends the initiate request to the child (2) The P-PCE (PCE5) sends the initiate request to the child
PCE (PCE3) via PCInitiate message for LSP (BN33-D). PCE (PCE3) via PCInitiate message for LSP (BN33-D).
(3) The PCE3 further propagates the initiate message to BN33. (3) The PCE3 further propagates the initiate message to BN33.
(4) BN33 initiates the setup of the LSP as per the path and reports (4) BN33 initiates the setup of the LSP as per the path and reports
skipping to change at page 14, line 46 skipping to change at page 13, line 51
(PCE5). (PCE5).
(l2) The node BN41 notifies the LSP state to PCE4 when the state is (l2) The node BN41 notifies the LSP state to PCE4 when the state is
"UP". "UP".
(13) The PCE4 further reports the status of the LSP to the P-PCE (13) The PCE4 further reports the status of the LSP to the P-PCE
(PCE5). (PCE5).
For LSP (S-BN41) For LSP (S-BN41)
(14) The P-PCE (PCE5) sends the initiate request to the child (14) The P-PCE (PCE5) sends the initiate request to the child
PCE (PCE1) via PCInitiate message for LSP (S-BN41). PCE (PCE1) via PCInitiate message for LSP (S-BN41).
(15) The PCE1 further propagates the initiate message to node S. (15) The PCE1 further propagates the initiate message to node S.
(16) S initiates the setup of the LSP as per the path and reports to (16) S initiates the setup of the LSP as per the path and reports to
the PCE1 the LSP status ("GOING-UP"). the PCE1 the LSP status ("GOING-UP").
(17) The PCE1 further reports the status of the LSP to the P-PCE (17) The PCE1 further reports the status of the LSP to the P-PCE
(PCE5). (PCE5).
(18) The node S notifies the LSP state to PCE1 when the state is (18) The node S notifies the LSP state to PCE1 when the state is
"UP". "UP".
(19) The PCE1 further reports the status of the LSP to the P-PCE (19) The PCE1 further reports the status of the LSP to the P-PCE
(PCE5). (PCE5).
Additionally: Additionally:
(20) Once P-PCE receives report of each per-domain LSP, it (20) Once P-PCE receives report of each per-domain LSP, it
should use suitable stitching mechanism, which is out of scope should use suitable stitching mechanism, which is out of scope
of this document. In this step, P-PCE (PCE5) could also of this document. In this step, P-PCE (PCE5) could also
initiate an E2E LSP (S-D) by sending the PCInitiate message to initiate an E2E LSP (S-D) by sending the PCInitiate message to
Ingress C-PCE (PCE1). It is also possible to stitch the per- Ingress C-PCE (PCE1).
domain LSP at the same time as the per-domain LSPs are
initiated as defined in [I-D.dugeon-pce-stateful-interdomain].
4. Other Considerations
4.1. Applicability to Inter-Layer
[RFC5623] describes a framework for applying the PCE-based
architecture to inter-layer (G)MPLS traffic engineering. The H-PCE
Stateful architecture with stateful P-PCE coordinating with the
stateful C-PCEs of higher and lower layer is shown in the figure
below.
+----------+
/| Parent |
/ | PCE |
/ +----------+
/ / Stateful
/ /
/ /
/ /
Stateful +---+/ /
Child + PCE + /
PCE Hi + Hi + /
+---+ /
+---+ +---+ / +---+ +---+
+ LSR +--+ LSR +........................+ LSR +--+ LSR +
+ H1 + + H2 + / + H3 + + H4 +
+---+ +---+\ +---+/ /+---+ +---+
\ + PCE + /
\ + Lo + /
Stateful \ +---+ /
C-PCE \ /
Lo \+---+ +---+/
+ LSR +--+ LSR +
+ L1 + + L2 +
+---+ +---+
Figure 2: Sample Inter-Layer Topology
All procedures described in Section 3 are applicable to inter-layer
path setup as well.
5. Other Considerations
5.1. Scalability Considerations
It should be noted that if all the C-PCEs would report all the LSPs
in their domain, it could lead to scalability issues for the P-PCE.
Thus it is recommended to only report the LSPs which are involved in
H-PCE, i.e. the LSPs which are either delegated to the P-PCE or
initiated by the P-PCE. Scalability considerations for PCEP as per
[RFC8231] continue to apply for the PCEP session between child and
parent PCE.
5.2. Confidentiality
As described in section 4.2 of [RFC6805], information about the It is also possible to stitch the per-domain LSP at the same
content of child domains is not shared for both scaling and time as the per-domain LSPs are initiated. This option is
confidentiality reasons. Along with the confidentiality during path defined in [I-D.dugeon-pce-stateful-interdomain].
computation, the child PCE could also conceal the path information, a
C-PCE may replace a path segment with a path-key [RFC5520],
effectively hiding the content of a segment of a path.
6. Security Considerations 4. Security Considerations
The security considerations listed in [RFC8231],[RFC6805] and The security considerations listed in [RFC8231],[RFC6805] and
[RFC5440] apply to this document as well. As per [RFC6805], it is [RFC5440] apply to this document as well. As per [RFC6805], it is
expected that the parent PCE will require all child PCEs to use full expected that the parent PCE will require all child PCEs to use full
security when communicating with the parent. security when communicating with the parent.
Any multi-domain operation necessarily involves the exchange of Any multi-domain operation necessarily involves the exchange of
information across domain boundaries. This is bound to represent a information across domain boundaries. This is bound to represent a
significant security and confidentiality risk especially when the significant security and confidentiality risk especially when the
child domains are controlled by different commercial concerns. PCEP child domains are controlled by different commercial concerns. PCEP
allows individual PCEs to maintain confidentiality of their domain allows individual PCEs to maintain confidentiality of their domain
path information using path-keys [RFC5520], and the hierarchical PCE path information using path-keys [RFC5520], and the hierarchical PCE
architecture is specifically designed to enable as much isolation of architecture is specifically designed to enable as much isolation of
domain topology and capabilities information as is possible. The LSP domain topology and capabilities information as is possible. The LSP
state in the PCRpt message SHOULD continue to use this. state in the PCRpt message must continue to maintain the internal
domain confidentiality when required.
The security consideration for PCE-Initiated LSP as per [RFC8281] is The security consideration for PCE-Initiated LSP as per [RFC8281] is
also applicable from P-PCE to C-PCE. also applicable from P-PCE to C-PCE.
Thus securing the PCEP session (between the P-PCE and the C-PCE) Thus securing the PCEP session (between the P-PCE and the C-PCE)
using mechanism like TCP Authentication Option (TCP-AO) [RFC5925] or using the TCP Authentication Option (TCP-AO) [RFC5925] or
Transport Layer Security (TLS) [RFC8253] is RECOMMENDED. Transport Layer Security (TLS) [RFC8253] mechanisms are recommended.
7. Manageability Considerations 5. Manageability Considerations
All manageability requirements and considerations listed in All manageability requirements and considerations listed in
[RFC5440], [RFC6805], [RFC8231], and [RFC8281] apply to Stateful H- [RFC5440], [RFC6805], [RFC8231], and [RFC8281] apply to Stateful H-
PCE defined in this document. In addition, requirements and PCE defined in this document. In addition, requirements and
considerations listed in this section apply. considerations listed in this section apply.
7.1. Control of Function and Policy 5.1. Control of Function and Policy
Support of the hierarchical procedure will be controlled by the Support of the hierarchical procedure will be controlled by the
management organization responsible for each child PCE. The parent management organization responsible for each child PCE. The parent
PCE must only accept path computation requests from authorized child PCE must only accept path computation requests from authorized child
PCEs. If a parent PCE receives report from an unauthorized child PCEs. If a parent PCE receives report from an unauthorized child
PCE, the report should be dropped. All mechanism as described in PCE, the report should be dropped. All mechanism as described in
[RFC8231] and [RFC8281] continue to apply. [RFC8231] and [RFC8281] continue to apply.
7.2. Information and Data Models 5.2. Information and Data Models
An implementation SHOULD allow the operator to view the stateful and An implementation should allow the operator to view the stateful and
H-PCE capabilities advertised by each peer. The PCEP YANG module H-PCE capabilities advertised by each peer. The PCEP YANG module
[I-D.ietf-pce-pcep-yang] can be extended to include details stateful [I-D.ietf-pce-pcep-yang] may be extended to include details for
H-PCE. stateful H-PCE deployment and operation, exact attributes to be
modeled is out of scope for this document.
7.3. Liveness Detection and Monitoring 5.3. 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].
7.4. Verify Correct Operations 5.4. 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 [RFC8231]. [RFC5440] and [RFC8231].
7.5. Requirements On Other Protocols 5.5. 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.
7.6. Impact On Network Operations 5.6. Impact On Network Operations
Mechanisms defined in [RFC5440] and [RFC8231] also apply to PCEP Mechanisms defined in [RFC5440] and [RFC8231] also apply to PCEP
extensions defined in this document. extensions defined in this document.
The stateful H-PCE technique brings the applicability of stateful PCE The stateful H-PCE technique brings the applicability of stateful PCE
as described in [RFC8051], for the LSP traversing multiple domains. as described in [RFC8051], for the LSP traversing multiple domains.
8. IANA Considerations 5.7. Error Handling between PCEs
Error types and notifications useful for correct PCEP operation
may be implemented for managing parent and child PCE interaction.
PCEP Error behavior propagation, notification and error criticality
level, are further defined in [I-D.ietf-pce-enhanced-errors].
6. Other Considerations
6.1. Applicability to Inter-Layer Traffic Engineering
[RFC5623] describes a framework for applying the PCE-based
architecture to inter-layer (G)MPLS traffic engineering. The H-PCE
Stateful architecture with stateful P-PCE coordinating with the
stateful C-PCEs of higher and lower layer is shown in the figure
below.
+----------+
| Parent |
/| PCE |
/ +----------+
/ / Stateful
/ / P-PCE
/ /
/ /
Stateful+-----+ / /
C-PCE | PCE |/ /
Hi | Hi | /
+-----+ /
+---+ +---+ / +---+ +---+
+ LSR +--+ LSR +........................+ LSR +--+ LSR +
+ H1 + + H2 + / + H3 + + H4 +
+---+ +---+\ +-----+/ /+---+ +---+
\ | PCE | /
\ | Lo | /
Stateful \ +-----+ /
C-PCE \ /
Lo \+---+ +---+/
+ LSR +--+ LSR +
+ L1 + + L2 +
+---+ +---+
Figure 2: Sample Inter-Layer Topology
All procedures described in Section 3 are applicable to inter-layer
(and therefore separate domains) path setup as well.
6.2. Scalability Considerations
It should be noted that if all the C-PCEs would report all the LSPs
in their domain, it could lead to scalability issues for the P-PCE.
Thus it is recommended to only report the LSPs which are involved in
H-PCE, i.e. the LSPs which are either delegated to the P-PCE or
initiated by the P-PCE. Scalability considerations for PCEP as per
[RFC8231] continue to apply for the PCEP session between child and
parent PCE.
6.3. Confidentiality
As described in section 4.2 of [RFC6805], information about the
content of child domains is not shared for both scaling and
confidentiality reasons. Along with the confidentiality during path
computation, the child PCE could also conceal the path information, a
C-PCE may replace a path segment with a path-key [RFC5520],
effectively hiding the content of a segment of a path.
7. IANA Considerations
There are no IANA considerations. There are no IANA considerations.
9. Acknowledgments 8. Acknowledgments
Thanks to Manuela Scarella, Haomian Zheng, Sergio Marmo, Stefano Thanks to Manuela Scarella, Haomian Zheng, Sergio Marmo, Stefano
Parodi, Giacomo Agostini, Jeff Tantsura and Rajan Rao for Parodi, Giacomo Agostini, Jeff Tantsura, Rajan Rao, Adrian Farrel and
suggestions. Haomian Zheng, for their reviews and suggestions.
10. References 9. References
10.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Requirement Levels", BCP 14, RFC 2119, Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC4655, August 2006,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc4655>.
[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>.
[RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel,
"Preserving Topology Confidentiality in Inter-Domain Path
Computation Using a Path-Key-Based Mechanism", RFC 5520,
DOI 10.17487/RFC5520, April 2009,
<https://www.rfc-editor.org/info/rfc5520>.
[RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the [RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the
Path Computation Element Architecture to the Determination Path Computation Element Architecture to the Determination
of a Sequence of Domains in MPLS and GMPLS", RFC 6805, DOI of a Sequence of Domains in MPLS and GMPLS", RFC 6805, DOI
10.17487/RFC6805, November 2012, 10.17487/RFC6805, November 2012,
<http://www.rfc-editor.org/info/rfc6805>. <http://www.rfc-editor.org/info/rfc6805>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP) Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231, Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017, DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>. <https://www.rfc-editor.org/info/rfc8231>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP) Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>. <https://www.rfc-editor.org/info/rfc8281>.
10.2. Informative References 9.2. Informative References
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>. <https://www.rfc-editor.org/info/rfc3209>.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol- Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473, Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
DOI 10.17487/RFC3473, January 2003, DOI 10.17487/RFC3473, January 2003,
<https://www.rfc-editor.org/info/rfc3473>. <https://www.rfc-editor.org/info/rfc3473>.
[RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A Framework for [RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A Framework for
Inter-Domain Multiprotocol Label Switching Traffic Inter-Domain Multiprotocol Label Switching Traffic
Engineering", RFC 4726, DOI 10.17487/RFC4726, November Engineering", RFC 4726, DOI 10.17487/RFC4726, November
2006, <https://www.rfc-editor.org/info/rfc4726>. 2006, <https://www.rfc-editor.org/info/rfc4726>.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel,
"Preserving Topology Confidentiality in Inter-Domain Path
Computation Using a Path-Key-Based Mechanism", RFC 5520,
DOI 10.17487/RFC5520, April 2009,
<https://www.rfc-editor.org/info/rfc5520>.
[RFC5623] Oki, E., Takeda, T., Le Roux, JL., and A. Farrel, [RFC5623] Oki, E., Takeda, T., Le Roux, JL., and A. Farrel,
"Framework for PCE-Based Inter-Layer MPLS and GMPLS "Framework for PCE-Based Inter-Layer MPLS and GMPLS
Traffic Engineering", RFC 5623, DOI 10.17487/RFC5623, Traffic Engineering", RFC 5623, DOI 10.17487/RFC5623,
September 2009, <https://www.rfc-editor.org/info/rfc5623>. September 2009, <https://www.rfc-editor.org/info/rfc5623>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925, Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <https://www.rfc-editor.org/info/rfc5925>. June 2010, <https://www.rfc-editor.org/info/rfc5925>.
[RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
skipping to change at page 20, line 35 skipping to change at page 20, line 11
[RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for [RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
Abstraction and Control of TE Networks (ACTN)", RFC 8453, Abstraction and Control of TE Networks (ACTN)", RFC 8453,
DOI 10.17487/RFC8453, August 2018, DOI 10.17487/RFC8453, August 2018,
<https://www.rfc-editor.org/info/rfc8453>. <https://www.rfc-editor.org/info/rfc8453>.
[I-D.ietf-pce-applicability-actn] [I-D.ietf-pce-applicability-actn]
Dhody, D., Lee, Y., and D. Ceccarelli, "Applicability of Dhody, D., Lee, Y., and D. Ceccarelli, "Applicability of
Path Computation Element (PCE) for Abstraction and Path Computation Element (PCE) for Abstraction and
Control of TE Networks (ACTN)", draft-ietf-pce- Control of TE Networks (ACTN)", draft-ietf-pce-
applicability-actn-11 (work in progress), April 2019. applicability-actn-12 (work in progress), May 2019.
[I-D.litkowski-pce-state-sync] [I-D.litkowski-pce-state-sync]
Litkowski, S., Sivabalan, S., and D. Dhody, "Inter Litkowski, S., Sivabalan, S., and D. Dhody, "Inter
Stateful Path Computation Element communication Stateful Path Computation Element communication
procedures", draft-litkowski-pce-state-sync-05 (work in procedures", draft-litkowski-pce-state-sync-05 (work in
progress), March 2019. progress), March 2019.
[I-D.ietf-pce-hierarchy-extensions] [I-D.ietf-pce-hierarchy-extensions]
Zhang, F., Zhao, Q., Dios, O., Casellas, R., and D. King, Zhang, F., Zhao, Q., Dios, O., Casellas, R., and D. King,
"Extensions to Path Computation Element Communication "Extensions to Path Computation Element Communication
Protocol (PCEP) for Hierarchical Path Computation Elements Protocol (PCEP) for Hierarchical Path Computation Elements
(PCE)", draft-ietf-pce-hierarchy-extensions-10 (work in (PCE)", draft-ietf-pce-hierarchy-extensions-11 (work in
progress), March 2019. progress), June 2019.
[I-D.ietf-pce-pcep-yang] [I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and j. Dhody, D., Hardwick, J., Beeram, V., and j.
jefftant@gmail.com, "A YANG Data Model for Path jefftant@gmail.com, "A YANG Data Model for Path
Computation Element Communications Protocol (PCEP)", Computation Element Communications Protocol (PCEP)",
draft-ietf-pce-pcep-yang-11 (work in progress), draft-ietf-pce-pcep-yang-11 (work in progress),
March 2019. March 2019.
[I-D.dugeon-pce-stateful-interdomain] [I-D.dugeon-pce-stateful-interdomain]
Dugeon, O., Meuric, J., Lee, Y., Dhody, D., and D. Dugeon, O., Meuric, J., Lee, Y., Dhody, D., and D.
Ceccarelli, "PCEP Extension for Stateful Inter-Domain Ceccarelli, "PCEP Extension for Stateful Inter-Domain
Tunnels", draft-dugeon-pce-stateful-interdomain-02 (work Tunnels", draft-dugeon-pce-stateful-interdomain-02 (work
in progress), March 2019. in progress), March 2019.
[I-D.ietf-pce-lsp-control-request] [I-D.ietf-pce-lsp-control-request]
Raghuram, A., Goddard, A., Yadlapalli, C., Karthik, J., Raghuram, A., Goddard, A., Yadlapalli, C., Karthik, J.,
Sivabalan, S., Parker, J., and M. Negi, "Ability for a Sivabalan, S., Parker, J., and M. Negi, "Ability for a
stateful Path Computation Element (PCE) to request and stateful Path Computation Element (PCE) to request and
obtain control of a LSP", draft-ietf-pce-lsp-control- obtain control of a LSP", draft-ietf-pce-lsp-control-
request-03 (work in progress), February 2019. request-04 (work in progress), June 2019.
Appendix A. Contributor Addresses [I-D.ietf-pce-enhanced-errors]
Pouyllau, et al., "Extensions to PCEP for Enhanced Errors"
, draft-ietf-pce-enhanced-errors-05 (work in progress),
February 2019.
Contributors
Avantika Avantika
ECI Telecom ECI Telecom
India India
EMail: avantika.srm@gmail.com EMail: avantika.srm@gmail.com
Xian Zhang Xian Zhang
Huawei Technologies Huawei Technologies
Bantian, Longgang District Bantian, Longgang District
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