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Framework for GMPLS and PCE Control of WSON

This document provides a framework for controlling wavelength switched optical networks (WSON) using GMPLS and PCE control plane. It discusses the routing and wavelength assignment (RWA) problem in WSONs and describes the subsystem models and information requirements for RWA.

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Framework for GMPLS and PCE Control of WSON

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  1. Framework for GMPLS and PCE Control of Wavelength Switched Optical Networks(WSON)& RWA Information for WSONs draft-bernstein-ccamp-wavelength-switched-02.txt draft-bernstein-ccamp-wson-info-01.txt Greg Bernstein gregb@grotto-networking.com Grotto Networking Young Lee ylee@huawei.com Huawei 70th IETF – Vancouver, December 2007

  2. 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) 70th IETF – Vancouver, December 2007

  3. 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. 70th IETF – Vancouver, December 2007

  4. 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 70th IETF – Vancouver, December 2007

  5. 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) 70th IETF – Vancouver, December 2007

  6. ROADM Example Ports #3-42 drop • 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) add … … line line 2-Degree ROADM Port #1 Port #2 … … add drop Ports #43-82 70th IETF – Vancouver, December 2007

  7. 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 70th IETF – Vancouver, December 2007

  8. 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. 70th IETF – Vancouver, December 2007

  9. 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 (Otani’s Label) • Wavelength Sets, Port Sets • Sparse matrix representation of asymmetric connectivity matrix 70th IETF – Vancouver, December 2007

  10. Example: Connectivity for a ROADM Ports #3-42 drop • 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. add … … line line 2-Degree ROADM Port #1 Port #2 … … add drop Ports #43-82 70th IETF – Vancouver, December 2007

  11. 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) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 70th IETF – Vancouver, December 2007

  12. Next Steps • Advance WSON Framework to a WG ID • Important for understanding the different RWA computational architectures involving PCE. Optimizing PCE’s 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”… 70th IETF – Vancouver, December 2007

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