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Signaling Extensions for Wavelength Switched Optical Networks

Greg Bernstein gregb@grotto-networking.comGrotto Networking

Young Lee ylee@huawei.comHuawei

draft-bernstein-ccamp-wson-signaling-00.txt

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Signaling Extensions for WSON

• Provides extensions to Generalized Multi-Protocol Label Switching (GMPLS) signaling for control of wavelength switched optical networks (WSON). These extensions build on previous work for the control of G.709 based networks.

• Based on Routing with Distributed WA via Signaling (RWA computational architectures defined in WSON Framework)

• Key extension areas:– Traffic parameters for optical signals– Wavelength Sets– Distributed Wavelength Assignment control

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Optical Signal Parameters

• Modulation Type (spectral characteristics)– General type such as NRZ, RZ, etc…

– Any modulation specific parameters such as duty cycle for RZ, etc…

• FEC Info– Note that more than one type of FEC maybe available.

• Analog Bandwidth– In case of analog modulation

• Spectral width/stability– Characteristic of the source laser (to be added in next

revision)

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Optical Signal Parameters

• Chose to encode these as Traffic Parameters– RSVP-TE Sender-TSPEC and FlowSpec

objects.– Similar to what was done in SONET/SDH,

G.709 cases.

• However some of these “parameters” may represent “choices”– Such as FEC or even bit rate and these may

depend on path impairments (see Giovani’s draft)

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Wavelength Sets

• General notions that comes up when:– describing wavelength constraints on ports– describing laser transmitter range– describing WDM link wavelength availability

• Most sensitive to space consumed

– performing distributed wavelength assignment via signaling

• Can be sensitive to space consumed

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Wavelength Sets

• Use label set concept

• Take advantage of structure of wavelength label– 50% space reduction for ranges and lists can be

helpful.

• Introduce wavelength bit map– big space savings possible for current and

future DWDM systems

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Bit map Wavelength Set

– Makes use of explicit channel spacing in lambda label– Takes advantage of relatively low count of lambda labels in existing

and future systems (current systems well under 1000 lambdas, typically 40-100 lambdas)

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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Action = 4 | Reserved | Num Wavelengths | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Grid | C.S. |S| Reserved | n for lowest frequency | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Bit Map Word #1 (Lowest frequency channels) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Bit Map Word #N (Highest frequency channels) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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Distributed Wavelength Assignment

• Choice of Assignment Algorithm– E.g., Random, First Fit, Least Loaded, etc…

• Directionality– Uni- or bi- directional assignment. Solves same

problem as presented by Sugang Xu and uses same recommended mechanism.

• Wavelength Set Metrics (supplemental)– Allows for the association of a metric with each lambda

in a wavelength set for use by distributed assignment algorithm.

– Example: multi-fiber assignment with least loaded lambda algorithm.

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Relation to other Drafts

• Giovani - GMPLS Signaling Extensions for Optical Impairment Aware Lightpath Setup – Includes FEC, Modulation Type but also has these as

options that could be negotiated– Additionally: addresses linear impairments and OSNR– Focuses on signaling based approach to optical

impairments, we are also interested in a PCE based approach so would consider some of this optional.

• Xu - Extensions to GMPLS RSVP-TE for Bidirectional Lightpath with the Same Wavelength – Addresses bi-directional distributed wavelength

assignment, proposes solution. We included this solution in our draft.

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Next Steps

• Determine how to move forward with various signaling drafts– Use a single general signaling draft or more

focused “point” solutions and summarize these in the framework draft.

– Wavelength sets – extend general label set to include a bit map or come up with a separate wavelength set that includes the bit map set option.