draft-ietf-pce-stateful-pce-app-06.txt   draft-ietf-pce-stateful-pce-app-07.txt 
PCE Working Group X. Zhang, Ed. PCE Working Group X. Zhang, Ed.
Internet-Draft Huawei Technologies Internet-Draft Huawei Technologies
Intended status: Informational I. Minei, Ed. Intended status: Informational I. Minei, Ed.
Expires: January 8, 2017 Google, Inc. Expires: April 1, 2017 Google, Inc.
July 07, 2016 September 28, 2016
Applicability of a Stateful Path Computation Element (PCE) Applicability of a Stateful Path Computation Element (PCE)
draft-ietf-pce-stateful-pce-app-06 draft-ietf-pce-stateful-pce-app-07
Abstract Abstract
A stateful Path Computation Element (PCE) maintains information about A stateful Path Computation Element (PCE) maintains information about
Label Switched Path (LSP) characteristics and resource usage within a Label Switched Path (LSP) characteristics and resource usage within a
network in order to provide traffic engineering calculations for its network in order to provide traffic engineering calculations for its
associated Path Computation Clients (PCCs). This document describes associated Path Computation Clients (PCCs). This document describes
general considerations for a stateful PCE deployment and examines its general considerations for a stateful PCE deployment and examines its
applicability and benefits, as well as its challenges and limitations applicability and benefits, as well as its challenges and limitations
through a number of use cases. PCE Communication Protocol (PCEP) through a number of use cases. PCE Communication Protocol (PCEP)
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This Internet-Draft will expire on January 8, 2017. This Internet-Draft will expire on April 1, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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
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4.1. Multi-PCE Deployments . . . . . . . . . . . . . . . . . . 5 4.1. Multi-PCE Deployments . . . . . . . . . . . . . . . . . . 5
4.2. LSP State Synchronization . . . . . . . . . . . . . . . . 5 4.2. LSP State Synchronization . . . . . . . . . . . . . . . . 5
4.3. PCE Survivability . . . . . . . . . . . . . . . . . . . . 6 4.3. PCE Survivability . . . . . . . . . . . . . . . . . . . . 6
5. Application Scenarios . . . . . . . . . . . . . . . . . . . . 6 5. Application Scenarios . . . . . . . . . . . . . . . . . . . . 6
5.1. Optimization of LSP Placement . . . . . . . . . . . . . . 6 5.1. Optimization of LSP Placement . . . . . . . . . . . . . . 6
5.1.1. Throughput Maximization and Bin Packing . . . . . . . 7 5.1.1. Throughput Maximization and Bin Packing . . . . . . . 7
5.1.2. Deadlock . . . . . . . . . . . . . . . . . . . . . . 9 5.1.2. Deadlock . . . . . . . . . . . . . . . . . . . . . . 9
5.1.3. Minimum Perturbation . . . . . . . . . . . . . . . . 11 5.1.3. Minimum Perturbation . . . . . . . . . . . . . . . . 11
5.1.4. Predictability . . . . . . . . . . . . . . . . . . . 12 5.1.4. Predictability . . . . . . . . . . . . . . . . . . . 12
5.2. Auto-bandwidth Adjustment . . . . . . . . . . . . . . . . 13 5.2. Auto-bandwidth Adjustment . . . . . . . . . . . . . . . . 13
5.3. Bandwidth Scheduling . . . . . . . . . . . . . . . . . . 13 5.3. Bandwidth Scheduling . . . . . . . . . . . . . . . . . . 14
5.4. Recovery . . . . . . . . . . . . . . . . . . . . . . . . 14 5.4. Recovery . . . . . . . . . . . . . . . . . . . . . . . . 14
5.4.1. Protection . . . . . . . . . . . . . . . . . . . . . 14 5.4.1. Protection . . . . . . . . . . . . . . . . . . . . . 14
5.4.2. Restoration . . . . . . . . . . . . . . . . . . . . . 16 5.4.2. Restoration . . . . . . . . . . . . . . . . . . . . . 16
5.4.3. SRLG Diversity . . . . . . . . . . . . . . . . . . . 16 5.4.3. SRLG Diversity . . . . . . . . . . . . . . . . . . . 16
5.5. Maintenance of Virtual Network Topology (VNT) . . . . . . 17 5.5. Maintenance of Virtual Network Topology (VNT) . . . . . . 17
5.6. LSP Re-optimization . . . . . . . . . . . . . . . . . . . 17 5.6. LSP Re-optimization . . . . . . . . . . . . . . . . . . . 17
5.7. Resource Defragmentation . . . . . . . . . . . . . . . . 18 5.7. Resource Defragmentation . . . . . . . . . . . . . . . . 18
5.8. Point-to-Multi-Point Applications . . . . . . . . . . . . 19 5.8. Point-to-Multi-Point Applications . . . . . . . . . . . . 19
5.9. Impairment-Aware Routing and Wavelength Assignment (IA- 5.9. Impairment-Aware Routing and Wavelength Assignment (IA-
RWA) . . . . . . . . . . . . . . . . . . . . . . . . . . 19 RWA) . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6. Security Considerations . . . . . . . . . . . . . . . . . . . 20 6. Security Considerations . . . . . . . . . . . . . . . . . . . 20
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
8. Contributing Authors . . . . . . . . . . . . . . . . . . . . 21 8. Contributing Authors . . . . . . . . . . . . . . . . . . . . 21
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
10.1. Normative References . . . . . . . . . . . . . . . . . . 22 10.1. Normative References . . . . . . . . . . . . . . . . . . 22
10.2. Informative References . . . . . . . . . . . . . . . . . 23 10.2. Informative References . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
[RFC4655] defines the architecture for a Path Computation Element [RFC4655] defines the architecture for a Path Computation Element
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| Time | LSP | Src | Dst | Demand | Routable | Path | | Time | LSP | Src | Dst | Demand | Routable | Path |
+------+-----+-----+-----+--------+----------+---------+ +------+-----+-----+-----+--------+----------+---------+
| 1 | 2 | B | E | 7 | Yes | B-C-E | | 1 | 2 | B | E | 7 | Yes | B-C-E |
| 2 | 1 | A | E | 7 | Yes | A-C-D-E | | 2 | 1 | A | E | 7 | Yes | A-C-D-E |
+------+-----+-----+-----+--------+----------+---------+ +------+-----+-----+-----+--------+----------+---------+
Table 11: Predictability LSP and demand time series 2 Table 11: Predictability LSP and demand time series 2
As can be shown in the example, both LSPs are routed in both cases, As can be shown in the example, both LSPs are routed in both cases,
but along very different paths. This would be a challenge if but along very different paths. This would be a challenge if
reliable simulation of the network is attempted. A stateful PCE can reliable simulation of the network is attempted. An active stateful
solve this through control over LSP ordering. PCE can solve this through control over LSP ordering. Based on
triggers such as a failure or an optimization trigger, the PCE can
order the computations and path setup in a deterministic way.
5.2. Auto-bandwidth Adjustment 5.2. Auto-bandwidth Adjustment
The bandwidth requirement of LSPs often change over time, requiring The bandwidth requirement of LSPs often change over time, requiring
resizing the LSP. In most implementations available today, the head- resizing the LSP. In most implementations available today, the head-
end node performs this function by monitoring the actual bandwidth end node performs this function by monitoring the actual bandwidth
usage, triggering a recomputation and resignaling when a threshold is usage, triggering a recomputation and resignaling when a threshold is
reached. This operation is referred as auto-bandwidth adjustment. reached. This operation is referred as auto-bandwidth adjustment.
The head-end node either recomputes the path locally, or it requests The head-end node either recomputes the path locally, or it requests
a recomputation from a PCE by sending a PCReq message. In the latter a recomputation from a PCE by sending a PCReq message. In the latter
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We would like to thank Cyril Margaria, Adrian Farrel, JP Vasseur and We would like to thank Cyril Margaria, Adrian Farrel, JP Vasseur and
Ravi Torvi for the useful comments and discussions. Ravi Torvi for the useful comments and discussions.
10. References 10. References
10.1. Normative References 10.1. Normative References
[I-D.ietf-pce-stateful-pce] [I-D.ietf-pce-stateful-pce]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful- Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-14 (work in progress), March 2016. pce-16 (work in progress), September 2016.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006, DOI 10.17487/RFC4655, August 2006,
<http://www.rfc-editor.org/info/rfc4655>. <http://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>.
skipping to change at page 23, line 15 skipping to change at page 23, line 15
10.2. Informative References 10.2. Informative References
[I-D.ietf-pce-gmpls-pcep-extensions] [I-D.ietf-pce-gmpls-pcep-extensions]
Margaria, C., Dios, O., and F. Zhang, "PCEP extensions for Margaria, C., Dios, O., and F. Zhang, "PCEP extensions for
GMPLS", draft-ietf-pce-gmpls-pcep-extensions-11 (work in GMPLS", draft-ietf-pce-gmpls-pcep-extensions-11 (work in
progress), October 2015. progress), October 2015.
[I-D.ietf-pce-pce-initiated-lsp] [I-D.ietf-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-ietf-pce-pce-initiated-lsp-05 (work in Model", draft-ietf-pce-pce-initiated-lsp-07 (work in
progress), October 2015. progress), July 2016.
[I-D.ietf-pce-stateful-sync-optimizations] [I-D.ietf-pce-stateful-sync-optimizations]
Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X.,
and D. Dhody, "Optimizations of Label Switched Path State and D. Dhody, "Optimizations of Label Switched Path State
Synchronization Procedures for a Stateful PCE", draft- Synchronization Procedures for a Stateful PCE", draft-
ietf-pce-stateful-sync-optimizations-05 (work in ietf-pce-stateful-sync-optimizations-05 (work in
progress), April 2016. progress), April 2016.
[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
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