Research on Wavelength Switched Optical Networks for the Next 10 years ICT Session 1 of PhD Academy Xin WANG TANAKA Lab. Waseda University Oct. 05, 2011

2 1. Background 2. GMPLS based WSON Architecture 3. Control Plane in WSON 4. Research Cases Outline

3 Optical network evaluation: opaque  translucent  transparent; Limitations: physical layer impairments(PLIs), technology and expenditures; Study network scenario: translucent WDM networks. Wavelength Switched Optical Network (WSON, RFC 6163); Generalized Multi-Protocol Label Switching (GMPLS, RFC 3945); O/E/O Transparency Time Fig. 1 Optical network evaluation O/E/O Optical link (fibres) WDM router Optical-electronic-optical At each site, the optical signal will undergo an O/E/O conversion At several sites, the signal will undergo an O/E/O conversion O/E/O 1. Background

4 Optical control plane locates between management plane and data plane ， i.e, Fig. 2. Data plane includes: MUX/DMUX; OXC; O/E transponders; 3R (Reamplifying, Reshaping and Retiming) regenerator pool: 3R regenerator shown in Fig. 3. GMPLS optical control plane: OSPF-TE; RSVP-TE; LMP, etc. Routing, wavelength assignment and 3R regenerator allocation; Centralized vs. Distributed. Management Plane Optical Control Plane OXC … … … … … 3R Module Pool O/E … … MUX DMUX … … Drop Add … … … Fig. 2 WSON operating layer Fig. 3 O/E/O 3R regenerator model Data plane 2. GMPLS based WSON Architecture

5 Fig. 5 Centralized control plane Advantages: Simple; No conflict. Drawbacks: No scalability; Require real time state info. 3. Control Plane – centralized mode Central Node (PCE) RWA TED OCP …… Node 1 Node 2 Node n RSVP-TE Extended OSPF-TE

6 Fig. 6 Distributed control plane 3. Control Plane – distributed mode (PCE) RWA TED …… OCP Node 1 OCP Node 2 OCP Node n Extended RSVP-TE Extended OSPF-TE Advantages: Scalable; Robust; Drawbacks: Conflict; Contention; Set-up delay.

7 Centralized control planeDistributed control plane Combined (Separated) RWA Connection request will be served one by one in a central node (NMS) relying on a complete knowledge of the network. Advantages: Optimizing resource usage; No resource assignment conflict; Easily being manipulated; Drawbacks: Processing load in the central node would be very high; Highly relying on the accurate network state information (hard to maintain in large networks); Weak scalability and poor survivability; Impracticable in realistic large-scale network; RWA calculation is conducted before signalling. Calculation can be performed either via a path computing element (PCE) or via a local CSPF Advantages: Calculation of RWA can be either centralized or decentralized; Scalable and survivable; Drawbacks: Highly relying on the accurate network state information (hard to maintain in large networks); High control traffic volume (e.g. OSPF); Resource assignment conflict and reservation contention; Poor performance. Routing + Distributed WA Each node provides a candidate path for a connection demand and the wavelength assignment is performed along this path in a distributed manner via signalling. Advantages: Calculation of RWA is decentralized; Mitigate the influence of inaccurate network state information Scalable and survivable; Drawbacks: Lightpath set-up delay Signalling packet also increase control traffic volume; Resource assignment conflict and reservation contention; Table. 1 RWA processing scheme in WSON 4. Research Cases

8 Thank you! Q&A