VT Reconfiguration
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Virtual Topology Adaptation in WDM Mesh Networks (for ECS 259: A. Gencata and B. Mukherjee, UC Davis) 3 VT Reconfiguration Traffic is dynamic: Traffic intensities change in time. VT may be inefficient for new traffic. Problem: How can we change the VT to accommodate the new traffic intensities? Solutions: Redesign the VT. Change some lightpaths Reconfiguration.
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VT Reconfiguration. Traffic is dynamic : Traffic intensities change in time. VT may be inefficient for new traffic. Problem : How can we change the VT to accommodate the new traffic intensities? Solutions : Redesign the VT. Change some lightpaths Reconfiguration. - PowerPoint PPT Presentation
Transcript of VT Reconfiguration
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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VT Reconfiguration
Traffic is dynamic: Traffic intensities change in time. VT may be inefficient for new traffic.
Problem: How can we change the VT to accommodate the new traffic intensities?
Solutions: Redesign the VT. Change some lightpaths Reconfiguration.
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Illustrative Example
0 1 2 30 0 1 0 01 0 0 1 02 0 0 0 13 1 0 0 0
0 1 2 30 0 0 0 11 1 0 0 02 0 1 0 03 0 0 1 0
0 1
3 2
0 1
3 2 3 2
0 1
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Motivation
Backbone network Slow changes in traffic
Change the virtual topology slowly.
t1 t2
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Earlier Approaches
Wait until VT becomes inefficient.
Run an optimization algorithm new VT.
Run a transformation algorithm.
Old VT New VT Branch-exchange method
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Our Approach
Observe the traffic
Adapt VT
New VT adjacent to old VT: Only 1 lightpath is different.
Simple reconfiguration.
Simple transition.
continuously.
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Optimization Goals
Using minimum number of lightpaths.
Load balancing.
Minimizing the number of changes: transition period’s length traffic rerouting
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Main Idea
Add or delete 1 lightpath at a time. Add a lightpath if some lightpaths are heavily
loaded. Delete a lightpath if some lightpaths are lightly
loaded. 2 parameters:
High watermark Low watermark
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Implementation
Traffic loads on links are observed periodically:Observation period T.
T should be small enough to follow the changes. Typically few 100s
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Adaptation Algorithm
Start with initial topology.Every T seconds do: Compare the load Li on each
lightpath i with the watermarks. if Li > WH then
add an appropriate lightpath. else if Li < WL then
delete an appropriate lightpath. else do not adapt the VT.
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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MILP
Objective: Minimize Lmax
Constraints:
C
LWkandW
C
Lk
where
kkkVV
PMin
LLH
PMax
H
LHHi j
oldij
i j
newij 1 (1)
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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MILP (cont.)
Constraints:
if Lmax > WH then
if Lmin < WL then
oldij
newij VVji ,,
oldij
newij VVji ,,
(2)
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Comparison
We compare MILP to a full-reconfiguration method.
Start with initial topology.Every T’ seconds do: Find the minimum #lightpaths for the new traffic pattern. Find the virtual topology such that: It has minimum #lightpaths. It requires minimum #changes from the previous topology.
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Results (MILP)N = 6W = 4Tx = 4WH = 0.8
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Results (MILP)
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Results (Heuristic)
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Results (Heuristic)
Virtual Topology Adaptation in WDM Mesh Networks(for ECS 259: A. Gencata and B. Mukherjee, UC Davis)
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Results (Heuristic)
