Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 1

Benefits of p-Cycles in a Mixed Protection and Restoration Approach

François Blouin, Anthony Sack, Wayne D. Grover, Hadi Nasrallah

Fourth International Workshop on the Design of Reliable Communication Networks (DRCN 2003)19-22 October 2003 - Banff, Alberta, Canada

October 21, 2003

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 2

Introduction

• Multiple protection and restoration methods may co-exist in optical mesh networks– Automatic protection switching (APS), shared backup path

protection (SBPP), mesh span restoration, redial, etc.

• Benefits of adding p-cycles to a set of these methods?• Benefits of planning network capacity jointly

for these methods?

New joint planning model

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 3

Capacity redundancy vs. Restoration time

Restoration time

Capacity redundancy

APS 1+1

p-Cycles

Shared Backup Path Protection

True Mesh Path Restoration

Mesh Span Restoration

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 4

Fixed CoP selection (without p-cycles)

Service model

Other possible CoPs, e.g. Unprotected and Redial, not included in analysis.

Class of Protection (CoP)

APS 1+1 60 ms

Restoration time

p-Cycles 80 ms

SBPP 200 ms

Network services

Restoration time requirement

15%

Demand mix (example case)

30%

55%

Applications

≤ 60 ms

≤ 80 ms

≤ 200 ms

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 5

Fixed CoP selection (with p-cycles)

Service model

Other possible CoPs, e.g. Unprotected and Redial, not included in analysis.

Class of Protection (CoP)

APS 1+1 60 ms

Restoration time

p-Cycles 80 ms

SBPP 200 ms

Network services

Restoration time requirement

15%

Demand mix (example case)

30%

55%

Applications

≤ 60 ms

≤ 80 ms

≤ 200 ms

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 6

Automatic CoP selection with upgrades

Service model

Other possible CoPs, e.g. Unprotected and Redial, not included in analysis.

Class of Protection (CoP)

APS 1+1 60 ms

Restoration time

p-Cycles 80 ms

SBPP 200 ms

Network services

Restoration time requirement

15%

Demand mix (example case)

30%

55%

Applications

≤ 60 ms

≤ 80 ms

≤ 200 ms

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 7

Planning models

Integer Linear Programming general model

(AMPL, CPLEX)• Minimal capacity•distance

for full restorability under single failures

• Selection of fastest CoPs

Separate optimization(fixed CoP selection)

Joint optimization(automatic CoP selection)

,m rj j j

j m r

c w s m

S M D

Withp-Cycles

Without p-Cycles(benchmark)

or

Min

Upgrade to faster CoP whenever economical

12

3 Withp-Cycles

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 8

Two network models

U.S.

EuropeAverage nodal degree = 4.73

Average nodal degree = 3.26

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 9

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Separate optimizationNo p-Cycles

Separate optimizationWith p-Cycles

Joint optimization With p-Cycles

To

tal c

ap

ac

ity

·dis

tan

ce

(x

10

00

wa

ve

len

gth

-km

)

APS

p-Cycles

SBP

Results – U.S. network

Benchmark

-3.4%

-8.7%

CoP upgraded demands:

32%

1 2 3

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 10

0

200

400

600

800

1000

1200

1400

1600

1800

Separate optimizationNo p-Cycles

Separate optimizationWith p-Cycles

Joint optimization With p-Cycles

To

tal

cap

acit

y·d

ista

nce

(x1

000

wav

elen

gth

-km

)

APS

p-Cycles

SBP

Results – Europe network

-11.6%

-14%

Benchmark

CoP upgraded demands:

24%

1 2 3

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 11

Class of Protection upgrade examples

Upgrade from p-cycle to APS 1+1

Upgrade from SBPP to p-cycle

working

p-cycle

A

CB

D

E

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 12

Class of Protection upgrade examples

Upgrade from p-cycle to APS 1+1

Upgrade from SBPP to p-cycle

working

p-cycle cap = 10

A

CB

D

E

APS “spare”

w1 cap = 10

w2 = 10

A

CB

D

E

w3 = 20

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 13

Conclusions

• p-Cycles could replace APS 1+1 for some traffic demands– where slight restoration time penalty is acceptable

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 14

Conclusions

• p-Cycles could replace APS 1+1 for some traffic demands– where slight restoration time penalty is acceptable

• New capacity planning model allowing automatic selection of protection & restoration method– Upgrade demand to faster CoP whenever economical

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 15

Conclusions

• p-Cycles could replace APS 1+1 for some traffic demands– where slight restoration time penalty is acceptable

• New capacity planning model allowing automatic selection of protection & restoration method– Upgrade demand to faster CoP whenever economical

• Mixed protection & restoration:– Adding p-cycles: 1% - 19% capacity savings– Jointly plan all CoPs: 4% - 22% capacity savings– Upgrades to faster CoP: 0 - 45%

Provide better service for some traffic without adding capacity

Benefits of p-Cycles in a Mixed Protection and Restoration Approach DRCN 2003 16

Thank you