University of AlbertaECE Department

Network Systems

Gangxiang Shen,Wayne D. Grover

Extending the p-Cycle Concept to Path-Segment Protection

Gangxiang Shen, Wayne D. Grover{gshen,grover@trlabs.ca}

URL: http://hey.to/gxshen

2University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Outline

Background and MotivationConcept of Flow p-CyclesFlow p-Cycle Design ModelTest Methods and ResultsOperational Aspects and Potential

ApplicationsConclusions

3University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Basic Approaches to Transport Network Survivability

p-CycleSpan p-cycles (since 1998)Flow p-cycles (our topic)

MeshSpan PathSBPP

EfficiencySpeed

Ring1+1 UPSRBLSR

4University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Background: Span-Protecting p-Cycles

Characteristic: Ring-like switching speed and mesh-like capacity efficiency

0

1

42

378

9 6 5

10

Straddling span

0

1

42

3

78

96 5

10On-cycle span

5University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Comparison between Ring and p-Cycle Protection

Ring network: p-Cycle:

Spare Capacity

Protection

CoverageAble to restore 9

spansAble to restore 19

spans

6University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

The Unique Position Span p-Cycles Occupy

Redundancy

Speed

“50 ms”

100 %50 % 200 %

Path rest, SBPP

Span (link)rest.

BLSR

200 ms

p -cycles: BLSR speed

mesh efficiency

7University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Motivation

All the studies so far on p-cycles consider “span-protecting” p-cycles, so it is natural to ask: Q. is there is “a path protection

equivalent to p-cycles?” -- A. Yes the answer is “Flow p-Cycles” !

8University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Concept of Flow p-CyclesCharacteristic: Protect spans that span p-cycles can protect as well as spans that

span p-cycles cannot protect (example: span 6-7 below) Intermediate node failure restoration (example: node 7) Path restoration –like spare capacity efficiency, 1:1 path

protection –like switching speed

0

1

42

378

9 6 5

10On-cycle span

Straddling span

?

?0

1

42

3

78

96 5

10

Straddling flow

9University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

The Position Flow p-Cycles Occupy

Redundancy

Speed

“50 ms”

100 %50 % 200 %

Path rest, SBPP

Span (link)rest.

BLSR

200 ms

p -cycles: BLSR speed

mesh efficiency

Flow p-cycles

10University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Various Flow-to-Cycle Relationships

s

d

s

d

s

d

s

d

s

d

(a) (b) (c) (d) (e)

Related basic concepts•Intersecting and non-intersecting•Intersection nodes•Intersection flow segment•Straddling and on-cycle flow relationship

11University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Mutual Capacity Consideration

Single span-failure causes multiple flow-failures simultaneously

Flow-based restoration is required

0

1

42

3

78

96 5

10

Straddling flow

12University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Flow p-Cycle Design Model for 100% Span Failure Restoration

Objective: minimize total spare capacity

Constraints: Affected flows upon a span failure must be fully

restored Number of cycle copies to build is set by the

largest span failure-specific simultaneous use for unit copies of cycle

The spare capacity on a span must be enough to support the number of copies of each p-cycle that overlies the span

13University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Test Networks

NSFNET, N=14,S=21, |P|=139

ARPA2, N=21,S=25, |P|=18

Bellcore, N=15,S=28, |P|=976

SmallNet, N=10,S=22, |P|=833

14University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Result: Performance Comparison between Various Protection Schemes

0

0.2

0.4

0.6

0.8

1

1.2

1.4

SP SR flow p-cycles

PR (stubno release)

PR (stubrelease)

Protection schemes

Re

du

nd

an

cy NSFNET

ARPA2

SmallNet

Bellcore

15University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Operational Aspects and Protocol

s

f

Rtable:

Failedspan ID

Affectedconnection IDAIS

001 33 1 1 e?

Rtable

d

a

b

eg

p-cycle 1

p-cycle 2

Span ID=001

Connection ID = 33

Failedspan ID

Affectedconnection ID

p-cycleID

RequiredCapacity

FlagPeer node

IDOutlet

span1 IDOutlet

span2 ID

AIS 001 33

AIS 001 33

! !

c

16University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Applications of the General Concept

OXCOXC

OXC

OXCOXC

OXC

OXC

OXC

OXC

p

Regional expressflow - protecting

p-cycle(s)

Localspan - protecting

-cycles

17University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Conclusions

Flow p-cycle concept was proposed and evaluated

Flow p-cycle method achieves path restoration –like spare capacity efficiency and 1:1 path protection –like restoration speed

18University of AlbertaECE Department

Network Systems

Gangxiang Shen and Wayne D. GroverICC2003, Anchorage, Alaska

Future Work

Identify the impacts from the network details and demand patterns

Further consider operational aspects and develop control protocol

Implement some applications of the general concept

Consider an evolutional scheme, pre-configured segments: p-segments

Compare to “ordinary” node-encircling p-cycles for node protection.