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Routing and Wavelength Assignment for Wavelength-Routed WDM Networks

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Routing and Wavelength Assignment for Wavelength-Routed WDM Networks

- Combined routing and wavelength assignment problem
- Routing
- static: ILP formulation
- dynamic: on-line algorithms
- Wavelength assignment
- static: graph coloring approach
- dynamic: heuristics
- A new wavelength assignment heuristic

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Combined Routing and Wavelength Assignment Problem

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Routing - ILP Formulation

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Routing - Algorithms For Dynamic Traffic

- Fixed routing (On/Off line)
- Fixed-alternate routing (On/Off line)
- Adaptive routing (On line)
- adaptive shortest path routing
- least congested path routing

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Wavelength Assignment with Known Lightpaths and Routes - Graph Coloring

- Construct an auxiliary graph G(V,E)
- Color the nodes of the graph G such that no two adjacent nodes have the same color
- Sequential graph coloring approaches

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Random

First-Fit

Least-Used/SPREAD

Most-Used/PACK

Min-Product

Least Loaded

MAX-SUM

Relative Capacity Loss

Wavelength Reservation

Protecting Threshold

Wavelength Assignment HeuristicsECS 259 -- H. Zang and B. Mukherjee, UC Davis

Illustrative Example

wavelengths

P1:(2,4)

3

2

1

0

0

1

2

3

4

5

6

Note: control network not shown. All wavelengths shown are for data traffic

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Calculation of Max-Sum

wavelengths

P1:(2,4)

3

2

1

WPC:

Wavelength-path

Capacity

0

0

1

2

3

4

5

6

Wavelength

selected:

0, 1, or 3

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Calculation of Relative Capacity Loss

wavelengths

P1:(2,4)

3

2

1

Wavelength selected:

1 or 3

0

0

1

2

3

4

5

6

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Simulation Network

2

1

2

1

1

0

3

1

1

1

1

5

4

2

Connection management protocol: link-state

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Results from Others’ Publication

5x5

bidirectional

mesh-torus,

load/W

= 25 Erlangs

Source: S. Subramaniam and R. A. Barry, “Wavelength assignment in fixed routing WDM networks,” Proc. ICC'97 - International Conference on Communications, Montreal, Canada, vol. 1, pp. 406-410, June 1997.

20-node

unidirectional

ring, load/W

= 1 Erlang

R

R

FF, MU

FF

MS

WC

WC

MU, MS

# of wavelengths

# of wavelengths

(a)

(b)

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Computational Complexity

- Wavelength reservation & Protecting threshold - constant
- Random & First-Fit - O(W)
- Min-Product & Least-Loaded - O(NW)
- Least-Used & Most-Used - O(LW)
- Max-Sum & Relative Capacity Loss - O(WN3)
- where W - # of wavelengths, N - # of nodes, L - # of links

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Wavelength

selected: 3

*

P1:(2,4)

Distributed RCL Algorithm3

2

1

0

0

1

2

3

4

5

6

RCL table at Node 2

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Characteristics of Distributed RCL

- Less state information is exchanged
- Faster computation of wavelength assignment upon a connection request
- Can be combined with adaptive routing

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Simulation Network

2

1

2

1

1

- Average propagation delay between two nodes: 0.107 ms
- Average hop distance: 1.53

0

3

1

1

1

1

5

4

2

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Simulation Results of Distributed RCL

Comparison of

DRCL with adaptive

routing and

RCL with

fixed routing

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Conclusion for RWA

L: # of links, N: # of nodes, W: # of wavelengths

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Future Research

- Survivable wavelength-routed WDM networks
- previous work: static traffic & single link failure [S. Ramamurthy 1998]
- higher layer protection -logical topology design with bundle cut in mind
- WDM layer protection - dynamic traffic

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

Future Research (Cont’d)

- Managing multicast connections in wavelength-routed WDM networks
- KMB
- Bellman-Ford
- Chain

ECS 259 -- H. Zang and B. Mukherjee, UC Davis

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