PCE Working Group H. Chen, Ed.
Internet-Draft Futurewei
Intended status: Standards Track Y. Zhuang, Ed.
Expires: December 18, 2020 Q. Wu
Huawei
D. Ceccarelli
Ericsson
June 16, 2020
PCEP Extensions for LSP scheduling with stateful PCE
draft-ietf-pce-stateful-pce-lsp-scheduling-17
Abstract
This document defines a set of extensions needed to the stateful Path
Computation Element (PCE) communication Protocol (PCEP), so as to
enable Labeled Switched Path (LSP) scheduling for path computation
and LSP setup/deletion based on the actual network resource usage and
the duration of a traffic service in a centralized network
environment as stated in RFC 8413.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 4
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
3. Motivation and Objectives . . . . . . . . . . . . . . . . . . 5
4. Procedures and Mechanisms . . . . . . . . . . . . . . . . . . 5
4.1. LSP Scheduling Overview . . . . . . . . . . . . . . . . . 5
4.2. Support of LSP Scheduling . . . . . . . . . . . . . . . . 7
4.2.1. LSP Scheduling . . . . . . . . . . . . . . . . . . . 7
4.2.2. Periodical LSP Scheduling . . . . . . . . . . . . . . 7
4.3. Scheduled LSP creation . . . . . . . . . . . . . . . . . 9
4.4. Scheduled LSP Modifications . . . . . . . . . . . . . . . 10
4.5. Scheduled LSP activation and deletion . . . . . . . . . . 11
5. PCEP Objects and TLVs . . . . . . . . . . . . . . . . . . . . 11
5.1. Stateful PCE Capability TLV . . . . . . . . . . . . . . . 11
5.2. LSP Object . . . . . . . . . . . . . . . . . . . . . . . 12
5.2.1. SCHED-LSP-ATTRIBUTE TLV . . . . . . . . . . . . . . . 12
5.2.2. SCHED-PD-LSP-ATTRIBUTE TLV . . . . . . . . . . . . . 15
6. The PCEP Messages . . . . . . . . . . . . . . . . . . . . . . 16
6.1. The PCRpt Message . . . . . . . . . . . . . . . . . . . . 16
6.2. The PCUpd Message . . . . . . . . . . . . . . . . . . . . 16
6.3. The PCInitiate Message . . . . . . . . . . . . . . . . . 17
6.4. The PCReq message . . . . . . . . . . . . . . . . . . . . 17
6.5. The PCRep Message . . . . . . . . . . . . . . . . . . . . 17
6.6. The PCErr Message . . . . . . . . . . . . . . . . . . . . 17
7. Implementation Status . . . . . . . . . . . . . . . . . . . . 18
8. Security Considerations . . . . . . . . . . . . . . . . . . . 19
9. Manageability Consideration . . . . . . . . . . . . . . . . . 19
9.1. Control of Function and Policy . . . . . . . . . . . . . 19
9.2. Information and Data Models . . . . . . . . . . . . . . . 19
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 19
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 20
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 20
9.6. Impact On Network Operations . . . . . . . . . . . . . . 20
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
10.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 20
10.1.1. Opt Field in SCHED-PD-LSP-ATTRIBUTE TLV . . . . . . 20
10.1.2. Schedule TLVs Flag Field . . . . . . . . . . . . . . 21
10.2. STATEFUL-PCE-CAPABILITY TLV Flag field . . . . . . . . . 21
10.3. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 21
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22
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12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
12.1. Normative References . . . . . . . . . . . . . . . . . . 22
12.2. Informative References . . . . . . . . . . . . . . . . . 23
Appendix A. Contributors Addresses . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction
The Path Computation Element Protocol (PCEP) defined in [RFC5440] is
used between a Path Computation Element (PCE) and a Path Computation
Client (PCC) (or other PCE) to enable path computation of Multi-
protocol Label Switching (MPLS) Traffic Engineering Label Switched
Paths (TE LSPs).
[RFC8231] describes a set of extensions to PCEP to provide stateful
control. A stateful PCE has access to not only the information
carried by the network's Interior Gateway Protocol (IGP) but also the
set of active paths and their reserved resources for its
computations. The additional state allows the PCE to compute
constrained paths while considering individual LSPs and their
interactions.
Traditionally, the usage and allocation of network resources,
especially bandwidth, can be supported by a Network Management System
(NMS) operation such as path pre-establishment. However, this does
not provide efficient usage of network resources. The established
paths reserve the resources forever, which can not be used by other
services even when they are not used for transporting any service.
[RFC8413] then provides a framework that describes and discusses the
problem, and defines an appropriate architecture for the scheduled
reservation of TE resources.
The scheduled reservation of TE resources allows network operators to
reserve resources in advance according to the agreements with their
customers, and allows them to transmit data about scheduling such as
a specified start time and duration, for example for a scheduled bulk
data replication between data centers. It enables the activation of
bandwidth usage at the time the service really being used while
letting other services use it when this service is not using it. The
requirement of scheduled LSP provision is mentioned in [RFC8231] and
[RFC7399]. A solution for providing more efficient network resource
usage for traffic engineering is desired. Also, for deterministic
networks [I-D.ietf-detnet-architecture], the scheduled LSP or
temporal LSP can provide a better network resource usage for
guaranteed links. This idea can also be applied in segment routing
[RFC8402] to schedule the network resources over the whole network in
a centralized manner as well.
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With this in mind, this document defines a set of extensions needed
to PCEP used for stateful PCEs so as to enable LSP scheduling for
path computation and LSP setup/deletion based on the actual network
resource usage duration of a traffic service. A scheduled LSP is
characterized by a starting time and a duration. When the end of the
LSP life is reached, it is deleted to free up the resources for other
LSPs (scheduled or not).
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2.1. Terminology
The following terminologies are re-used from existing PCE documents.
o Active Stateful PCE [RFC8231];
o Passive Stateful PCE [RFC8231];
o Delegation [RFC8231];
o PCE-Initiated LSP [RFC8281];
o PCC [RFC5440], [RFC8231];
o PCE [RFC5440], [RFC8231];
o TE LSP [