exploiting forcer structure to serve uncertain demands and minimize redundancy of p-cycle networks...

Exploiting Forcer Structure to Serve Uncertain Exploiting Forcer Structure to Serve Uncertain Demands and Minimize Redundancy Demands and Minimize Redundancy

of of pp-Cycle Networks-Cycle Networks

Gangxiang Shen & Wayne D. Grover Gangxiang Shen & Wayne D. Grover TRLabs and University of AlbertaTRLabs and University of Alberta

Edmonton, AB, CanadaEdmonton, AB, Canada

web site for related research group: web site for related research group:

http://www.ece.ualberta.ca/~grover

OptiComm 2003, OptiComm 2003, October 13-17, Dallas, Texas October 13-17, Dallas, Texas

Gangxiang Shen and Wayne D. Grover OptiComm ‘03 Dallas 2

OutlineOutline

• Conventional survivable network design

• What is a forcer and what is the meaning of a forcer in a

p-cycle network?

• Exploitation of forcer structure for a p-cycle network

• Experiments and results

• Conclusion


Conventional Survivable Network DesignConventional Survivable Network Design

1 2 3 4 5 6

1

2

3

4

5

6

Node index

Node in

dex

Demand matrix

3 1 2 2 3

2 2 3 2

1 1 3

3 3

3

2

3

4

6

1

Network topology

52

3

4

6

1

Network with working capacity

5w=9

6

6

2

6

54

5 3

2

3

4

6

1

Network with protection capacity

5s=6

9

4

5

4

50

1 5

Survivable network design methods, e.g., span

restoration, path restoration, p-cycle, SBPP, flow p-cycle,

path-segment restoration…

Here span restoration method was employed

? Who forces this span to

require 5-unit spare capacity?


What is a Forcer?What is a Forcer?

“A forcer is any span for which an increase in network total spare capacity is required (to retain restorability) if the span’s working capacity is increased.”

Have a look at the previous example again

2

3

4

6

1

Network with working capacity

5w=9

6

6

2

6

54

5 3

2

3

4

6

1

Network with protection capacity

5s=6

9

4

5

4

50

1 5

2

3

4

6

1

Network forcers

5

forcers

3

6

4 2

non-forcers


Forcer in Forcer in pp-Cycle Networks-Cycle Networks

0

11

3

7

69

12

10

12

4

58

Straddling span

On-cycle span

p-cycle

Forcer span

A p-cycle with 3-unit spare capacity

6

0

w=6

3

2

1

3

1

5

4

1

2

“A forcer is any span for which an increase in p-cycle spare capacity (corresponding to total network spare capacity) is required (to retain restorability)

if the span’s working capacity is increased.”

A p-cycle with 3-unit spare capacity

6

3

w=6

3

3

3

3

3

6

6

3

3

p-cycle protected envelope


Forcing Chain in Forcing Chain in pp-Cycle Networks-Cycle Networks

Span working capacity


p-cycle protected envelopeProtected working capacity envelope


Span protection capacity

How should we deal with this

gap?

p-cycle 3p-cycle 1p-cycle 2

p-cycle 4 p-cycle N

p-cycle spare capacity


How to Exploit the Gaps?How to Exploit the Gaps?

Forcer Filling: adding working capacity to non-forcers to make them forcers;

the added capacity can be used to serve future uncertain demands. … the basic idea of this paper

Protected working capacity envelope



Span working capacity after forcer filling Extra protected span working capacity for future uncertain demands

Just use it! No need to pay for anything for protection

!


Forcer Maximized Design and its Relation to Forcer Maximized Design and its Relation to Conventional DesignConventional Design

Regular design

Working demand pattern

Networktopology

Minimize requiredspare capacity for

restorability

Forcer maximized design

Span spare capacitybudget

Maximize extraservable protectedworking channels

Networktopology

Total network spare capacitybudget


Three ILP ModelsThree ILP Models

• Common ground of the three models

--Objective: Maximize total servable protected working channels

--Conditions: 1. Ensure the restorability of working capacity

2. Ensure spare capacity shall be within budgets

• Forcer analyzer (FA) model

Maximize extra servable working channels, but disallowing to touch the existing working channels

• Forcer maximization-1 (FM-1)

Maximize servable working channels given span spare capacity budgets, but allowing to

change the existing working channels

• Forcer maximization-2 (FM-2)

Maximize servable working channels given total network spare capacity budgets, but allowing to change the existing working channels


Test Methods and Network TopologiesTest Methods and Network Topologies

1. Two metrics: hop-based and physical distance-based2. Dijkstra’s shortest path algorithm is used to find the route for a working path3. Demand matrixes are randomly generated within the range [1-20] for each node pair

NSFNET ARPA-2

SmallNet COST239


Test Methods and Network Topologies (cont’)Test Methods and Network Topologies (cont’)

Level-3 network


Results of the FA Model for Results of the FA Model for pp-Cycle Networks-Cycle Networks

0

10

20

30

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90

Hop-based Distance-based

Pe

rce

nta

ge

s o

f e

xtr

a s

erv

ab

le w

ork

ing

ch

an

ne

ls w

ith

ou

t a

ny

inc

rea

se

in s

pa

rec

ap

ac

ity

bu

dg

et ARPA2

NSFNET

SmallNet

COST239

Level3

Percentages of extra working channels that can be served in p-cycle networks without any increase in span spare capacity budget


Redundancy Comparison between Various Survivable Redundancy Comparison between Various Survivable

SchemesSchemes

1: Conventional design 2: Forcer analyzer (FA) 3: Forcer maximization-1 (FM-1) 4: Forcer Maximization-2 (FM-2)


Concluding DiscussionConcluding Discussion

• A simple but efficient forcer analyzer is developed

• Two forcer maximization design models are proposed

• Experiments show that there is a rich “protected working capacity bank” under the forcer structure formed in the conventional survivable network design

• The direct use of protected capacity in the “bank” to serve future uncertain demands

……”Just use it! No need to pay any extra spare capacity for protection! (Its already protected)”

• Neighbouring concept to this study is to use “protected working capacity envelope (PWCE)” to serve dynamic protected demands for efficiency and simplicity

Thanks!


How to Deal with the Gaps?How to Deal with the Gaps? --Clipping and Filling--Clipping and Filling

Forcer Clipping: clipping forcers to make non-forcers become forcers as well

and to improve network spare capacity efficiency




Remaining span working capacity Clipped span working capacity

Ring covering

exploiting forcer structure to serve uncertain demands and minimize redundancy of p-cycle networks...

Documents

cycle span pcycle forcer

pcycle networks span

flow pcycle

pcycle network experiments

added capacity

network total spare

total network spare

unit spare capacity