Framework for GMPLS and PCE Control of Wavelength Switched Optical Networks (WSON)

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Framework for GMPLS and PCE Control of Wavelength
Switched Optical Networks(WSON) RWA
Information for WSONs
draft-bernstein-ccamp-wavelength-switched-02.txt d
raft-bernstein-ccamp-wson-info-01.txt
Greg Bernstein gregb_at_grotto-networking.com Grott
o Networking Young Lee ylee_at_huawei.com Huawei
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Authors/Contributors

• Snigdho Bardalai (Fujitsu)
• Greg Bernstein (Grotto Networking)
• Diego Caviglia (Ericsson)
• Wataru Imajuku (NTT)
• Daniel King (Aria Networks)
• Young Lee (Huawei)
• Dan Li (Huawei)
• Itaru Nishioka (NEC Corp.)
• Lyndon Ong (Ciena)
• Jonathan Sadler (Tellabs)

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WSON Framework

• Describes wavelength switched optical networks
  (WSON), subsystems and associated processes.
  Emphasizing those aspects that are different from
  other technologies that utilize a GMPLS and PCE
  control plane.
• Optical impairments are not currently considered
  in any depth since different approaches to
  impairments are used in different WSONs.
• Summarize implications to GMPLS routing and
  signaling, and to PCE protocols.

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Routing and Wavelength Assignment (RWA)

• WSONs with limited or no wavelength converters
  must perform RWA
• Known hard problem (NP complete) ? Benefits from
  PCE architecture.
• Two basic approaches combined RWA (more optimal)
  and two step routing followed by wavelength
  assignment.
• RWA approaches lead to different computational
  architectures
• Combined RWA on a PCE
• Routing and WA on separate PCEs
• Routing with distributed WA via Signaling

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WSON Subsystem Models

• WDM links
• Channel spacing, usable wavelengths, filter
  constraints
• Laser Transmitter/Modulator
• Tunability, tuning range, tuning time, (to come
  line width)
• Spectral characteristics (modulation type), clock
  rate, FEC type
• ROADMs, FOADMs, and OXCs (oh, my!)
• Some of the most popular WSON switching elements
  are extremely asymmetric. We must have a
  description of this as an input to path
  computation.
• Wavelength Converters and Regenerators
• Technology, ranges, constraints on signal type
  (1R, 2R, 3R)

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ROADM Example
Ports 3-42
drop
add


line
line
2-Degree ROADM
Port 1
Port 2


add
drop
Ports 43-82

• Constraints
• Any to Any connectivity is NOT supported!
• Example ingress ports 3-42 (adds) can only
  egress on port 1
• Various wavelength restrictions can apply to
  drop ports (colored or colorless, single
  wavelength or multiple wavelengths)

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PCE Information Requirements

• Combined RWA (PCE)
• Routing PCE WA PCE
• Switch/ROADM connectivity matrix
• Switch/ROADM wavelength restrictions
• WDM link lambda ranges and spacing
• Laser transmitter range
• Wavelength conversion capability
• Wavelength availability
• Routing PCE distributed WA via Signaling
• Switch/ROADM connectivity matrix

Minimum requirements
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Information for RWA in WSON

• Provides compact encodings for information needed
  for path computation and wavelength assignment in
  wavelength switched optical networks. Such
  encodings can be used in extensions to GMPLS
  routing for control of wavelength switched
  optical networks or used to send info directly to
  PCEs.
• From WSON Framework different RWA computational
  architectures have different info needs.

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RWA Info
Information Static/Dynamic
Node/Link ----------------------------------------
-------------- Connectivity matrix Static Node
Per port wavelength restrictions Static Node WDM
link (fiber) lambda ranges Static Link WDM link
channel spacing Static Link Laser Transmitter
range Static Link Wavelength Conversion Static
Node Wavelength Availability Dynamic Link

• Key concepts for compact representations
• Wavelength encoding (Otanis Label)
• Wavelength Sets, Port Sets
• Sparse matrix representation of asymmetric
  connectivity matrix

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Example Connectivity for a ROADM
Ports 3-42
drop
add


line
line
2-Degree ROADM
Port 1
Port 2


add
drop
Ports 43-82

• 82 Port ROADM
• 164 uni-directional ports ? Amn is 82 x 82
  matrix, i.e., 6724 entries
• Can represent with only 30 32 bit words. See
  example in section 4.1 of draft.

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Example Wavelength Availability Info

• 40 Channel C-Band WDM subsystem
• with 100GHz spacing with lowest frequency
  192.0THz (1561.4nm) and highest frequency
  195.9THz (1530.3nm). Now suppose the following
  channels are available (THz)192.0, 192.5, 193.1,
  193.9, 194.0, 195.2, 195.8
• Compactly represented by four 32 bit words
  (regardless of number of available channels). See
  section 3.3.3 of draft.

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 40
-------------------------
------- Grid C.S. S Reserved
n for lowest frequency -11
-------------------------
------- 1 0 0 0 0 1 0 0 0 0 0 1 0 0 0
0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0
-------------------------
------- 1 0 0 0 0 0 1 0 Not used in
40 Channel system (all zeros)
----------------------
----------
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Next Steps

• Advance WSON Framework to a WG ID
• Important for understanding the different RWA
  computational architectures involving PCE.
  Optimizing PCEs will need more info on the WSON.
• Continue to update as solution drafts progress
  and issues are discovered and resolved.
• Advance WSON Info to a WG ID
• Common repository of WSON encodings for use in
  Signaling, Routing and PCEP
• Use in scalability studies of routing and
  alternative.
• Alternative Methods of Information Transfer?
• Should we consider alternative methods to deliver
  information to PCE? PCE discovery and PCEP
  provide hooks