~1~OptiComm ’02July 2002Wavelength Band Switching in Multi-granular All-Optical NetworksXiaojun CaoXiaojun CaoIn collaboration with In collaboration with Yizhi XiongYizhi Xiong, , Vishal AnandVishal AnandandandChunming QiaoChunming QiaoLANDER, CSE DepartmentLANDER, CSE DepartmentSUNY at BuffaloSUNY at Buffalo~2~OptiComm ’02July 2002Outline Concept of wavelength band switching (WBS) Integer linear programming (ILP) model for WBS. Heuristic algorithms for WBS Simulation results Conclusion~3~OptiComm ’02July 2002Wavelength Band Switching A new WDM switching hierarchy To reduce port count and its associated complexity in Optical cross-connect nodes (OXC) Use WBS in conjunction with a multi-granular OXC, MG-OXC Wavelength band: a group of several wavelengthsBDABCDACλ0Band of 4 wavelengthsλ3b0λ1λ2~4~OptiComm ’02July 2002Multi-granular optical cross-connect (MG-OXC)..........................................WXCBXCFXCWdropBdropFdropWaddBaddFaddWTBBTWFTB BTFWXCLayerBXCLayerFXCLayerArchitecture of an MG-OXC~5~OptiComm ’02July 2002Classification of WBS WBS SchemesConsecutive λ set Random λ setArbitrary λ setFixed λ setFixed # WConsecutive λ set Random λ setVariable # WConsecutive λ set Random λ setVariable # WFixed # WFixed # B Variable # B(1)(2)(3)(4)(5)(6)(7) (8)~6~OptiComm ’02July 2002Waveband assignment strategies(1) grouping the lightpaths with the same source-destination pair only; (2) grouping the lightpaths from the same source only; (3) grouping the lightpaths with same destination only; (4) grouping the lightpaths with common intermediate links (from any source to any destination).  Strategy (4) is the most general~7~OptiComm ’02July 2002ILP model for WBS Based on waveband assignment strategy (4). Objective: minimize the total number of MG-OXC ports in the network. ??For more detail, we referred to our original paper.~8~OptiComm ’02July 2002Heuristic Algorithms Waveband Oblivious (but optimal) RWA (WBO-RWA) Balanced Path with Heavy-Traffic first waveband assignment (BPHT)~9~OptiComm ’02July 2002WBO-RWA Use ILP formulations for traditional RWA that minimize the total number of used wavelength-hop (WH). Then group the assigned wavelengths into bands and calculate the number of required ports. The grouping is done as an afterthought, completely oblivious to the existence of wavebands~10~OptiComm ’02July 2002BPHT1. Load Balanced Routing2. Wavelength AssignmentsA.) First, consider all traffic with path length or hops (hp>=2) Define a set Qsdfor every node pair (s,d), which includes all its subpaths. Calculate weight for each set  Starting with Largest weight set, 1. assign wavelengths to traffic s->d, 2. assign wavelengths to traffic from s3. assign wavelengths to traffic to d4. Recursively assign wavelengths, until all sub-paths are assignedB.) Finally, consider the one-hop traffic.3. Waveband Switching∑∈=sdQpppsdThW *~11~OptiComm ’02July 2002BPHT exampleS0S1S2S3S434265d = S521131412131415 =×+×+×+×+×+×=×=∑∈sdQpppsdthWS51S0S1S2S3S4S5λ0λ1b0λ2b1λ3λ4λ5b2~12~OptiComm ’02July 2002Network Topology6107543821149131112456123~13~OptiComm ’02July 2002 Performance Metrics– Total port number ratio T(a):– Max port number ratio M(a):– Used wavelength channels ratio W(a):– ??Improvement in number of ports is: 1-T(a)Performance EvaluationOXCordinaryofOXCTotalaorithmaWBSguWXCBXCFXCTotalnnnn−++)(''lgsin)(OXCordinaryofOXCMaxaorithmaWBSguWXCBXCFXCMaxnnnn−++)(''lgsin)(WBSwithoutRWAoptimalbyusedhopaorithmaWBSbyusedhop−−λλ''lg~14~OptiComm ’02July 2002Simulation Results I Results for the six-node network~15~OptiComm ’02July 2002Simulation Results II Results of the NSF network—Random trafficW*B=120 (number of wavelengths per fiber)~16~OptiComm ’02July 2002Simulation Results III Results of the NSF network—Uniform traffic– B=30, W=4~17~OptiComm ’02July 2002Conclusion We explore the advantage of WBS, and intelligent WBS heuristics. Developed ILP formulations and heuristics to consider the efficient design of MG-OXC optical networks. Intelligent WBS heuristics (such as BPHT) can save considerably on port count.Bad heuristics such as WBO-RWA may need even more ports than ordinary-OXC network. Waveband granularity (i.e. band size) has a large effect on the performance. There is a trade-off between wavelength-hop used and the total port count in MG-OXC