IETF-70th Vancouver 1

Extensions to GMPLS RSVP-TE for Bidirectional Lightpath with the Same Wavelength

draft-xu-rsvpte-bidir-wave-01

Sugang Xu, Hiroaki Harai, Daniel Kingxsg@nict.go.jp, harai@nict.go.jp, daniel.king@aria-networks.com

IETF-70th Vancouver 2

• Special optical network scenarios for bidirectional lightpath provisioning– Fixed tuned wavelength transponders – Fixed wavelength multiplexers/demultiplexers like AWGs – Some types of ROADM need to add/drop wavelength simultaneously– Wavelength continuity constraint

• Solution of port-remapping problem of bidirectional lightpath with differendifferent wavelengths t wavelengths using fix-tuned wavelength media converter (MC)

• True needs ofTrue needs of FastFast ProvisioningProvisioning capability – In cases of configuration errorsconfiguration errors, transceiver failure, failure, etc.– Quick recovery capabilitiesQuick recovery capabilities are critical to network stability.

To Recap: Support for Bidirectional Lightpath with the SameWavelength on Both Directions Would Be Advantageous

MCMC

MCMC

MCMC

GEGE

GEGE

GEGE

Optical End Node Core Node

MCMC

MCMC

MCMC

GEGE

GEGE

GEGE

Optical End Node Core Node

Lack port-remapping flexibility With flexibility by OXC

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Do Solutions Exist?• Two unidirectional lightpaths in converse directions with the same wave

length (A1)

– Sequentially verify the same wavelength availability in both directions and crankback if failure.

• Label set and Upstream label + crankback (A2)

– Specify wavelength on both directions

• Label set and Upstream Label set (A3)

– Add constraint in wavelength available information updating process on both directions in Label set and Upstream Label set

• Label Set Object and Bidirectional Lightpath (Prop)

– Using LSP_ATTRIBUTESLSP_ATTRIBUTES Object [RFC 4420]

– Upstream-and-Downstream common free wavelengths information updating at each node and carried by Label setLabel set

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Shorter Provisioning Time and Lower Blocking Probability

1 round message exchanging

a b c

Path Msg

Resv Meg

Path Msg

Resv Meg

Avg. Provisioning Time (W=32, Δt=0.01s) Blocking Probability (W=32)

HbP 2

2A_ )1(1

1

1 )1(n

bn

bt PnPHRt

Hb

WHb

P

P

)1(1

])1(1[

Up_1A_

Down_1A_

WHbb PP ])1(1[ 2

3A_Prop_

Single wavelength occupation rate/link

WW: Number of wavelengthsHH: Number of Hops

A1A1: Uni SetupsA2A2: With UpLabel

A3A3: With UpLabel setPropProp: With Label set

:

RtRt: Avg. provisioning time

PPbb: Blocking probability

Avg. time per hop:t

IETF-70th Vancouver 5

PCE Applicability - Link Bundling Issue

• PCE path computation problems– May occur when computing bidirectional lightpaths. In a GMPLS network whe

re multiple component links are aggregated into a link bundle and advertised as a single bidirectional TE link, the Traffic Engineering Database (TED) may indicate the availability of a particular lambda in both directions on the TE link. HHowever, it may actually be the case that the lambda is only available in one owever, it may actually be the case that the lambda is only available in one direction on one component link, and the other direction is only available direction on one component link, and the other direction is only available on a different component linkon a different component link.. In this scenario, creating an end-to-end path that uses the same lambdas and the same component links in both directions presents a PCE path computation problem.

– Use signaling to verifyverify the solution received from PCE.

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PCE Applicability - Unified Signaling Solutions

• With RWA done by PCE – Given a routing and wavelength assignment solution e.g. derived from a PCE,

an ingress node can put one wavelength labelone wavelength label in Label set or a Suggested labelSuggested label object to specify the wavelength.

• With only routing done by PCE– An ingress node can set one or more available wavelength label objects in Lab

el set, and let the egress nodeegress node resolve the wavelength assignment in a distributed fashion.

• No interaction with PCE – Because this signaling solution can resolve wavelength assignment problem its

elf, even without interaction with a PCE, by using an explicit route e.g. manually, it is still possible to establish a bidirectional lightpath. For example, for quicquick recoveryk recovery from failures, bidirectional signaling may negate a PCE request.

IETF-70th Vancouver 7

Next Steps

• Consensus is that support for same wavelength bidirectional lightpath is important for quick recovery, and fast provisioning.

• Is this proposal necessary right now? Feedback from the previous WG has been positive, but there is a need to clarify requirements.– Do we need requirements document?

• The authors will continue to work on the draft and would like to request additional feedback from WG. Especially from Operators and relevant Vendors.– Referenced in “draft-bernstein-ccamp-wson-signaling-00.txt”