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Topology Mapping. Bo Sheng Sept. 15. Outline. Overview Solutions LTM ACE Problems and discussion Conclusion. Introduction. Topology mapping Mismatch between overlay and physical infrastructure Topology optimization. Introduction. Traffic problem Facts

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Presentation Transcript
topology mapping

Topology Mapping

Bo Sheng

Sept. 15

outline
Outline
  • Overview
  • Solutions
    • LTM
    • ACE
  • Problems and discussion
  • Conclusion
introduction
Introduction
  • Topology mapping
    • Mismatch between overlay and physical infrastructure
    • Topology optimization
introduction1
Introduction
  • Traffic problem
    • Facts
      • 95% of any pairs of Gnutella nodes are within 7 hops
      • 50,000 nodes generate 1G/second, 330T/month
    • Reasons
      • Blind flooding
        • Cycles, merge of multiple paths, neighbors exchange
      • Topology problem
        • Multiple times over a physical link
introduction2
Introduction
  • Perfect match

S

S

Network infrastructure

Overlay network

introduction3
Introduction
  • Mismatch

N3

N1

4

5

2

3

S

S

2

5

4

N2

Network infrastructure

Overlay network

topology mismatch
Topology Mismatch
  • Problems
    • Randomly choosing neighbors
    • Logically close, but physically far away

S

P

N1

N2

topology mismatch1
Topology Mismatch
  • Problems
    • Unnecessary traffic
      • Inefficient utilization of bandwidth
      • Only 2%~5% Gnutella connections link nodes within a single AS (autonomous system)
      • More than 40% Gnutella nodes are located within top 10 AS
    • Delayed response
    • Do we need long-distance neighbors?
topology mismatch2
Topology Mismatch
  • Solutions to traffic problem
    • Selective flooding
    • Topology optimization
      • Avoid cycles
      • Mapping

For each message, how many times it is delivered over a single physical link?

performance metrics
Performance Metrics
  • Traffic cost
  • Search scope
  • Response time
  • Overhead
approaches
Approaches
  • Location-aware Topology Matching (LTM), INFOCOM 2004
  • Adaptive Connection Establishment (ACE), ICDCS 2004
slide12
LTM
  • Three main operations
    • TTL-2-detector flooding
      • Message format
        • Short Source IP& timestamp
        • Long Source IP& timestamp, TTL1 IP& timestamp
        • d(i,S,v)
      • Link cost

IP(S),T(S)

S

N1

N2

IP(S),T(S)

IP(N1),T(N1)

d(i,S,1)

d(i,S,0)

slide13
LTM
  • Three main operations
    • Low productive connection cutting
      • Case1: P receives d(i,S,1) and d(i,S,0)

S

N

P

will-cut list

slide14
LTM
  • Three main operations
    • Low productive connection cutting
      • Case2: P receives multiple d(i,S,0)

S

N1

N2

P

slide15
LTM
  • Three main operations
    • Low productive connection cutting
      • Case3: P receives one d(i,S,1) and multiple d(i,S,0)

S

N1

N2

P

cut list

slide16
LTM
  • Three main operations
    • Source peer probing

S

N1

P

slide17
LTM

Step2.case2

S

S

Step3

N1

N1

N2

P

P

slide18
LTM

Step2.case3

Step2.case2

S

S

N1

N1

N2

N2

P

P

Step2.case3

Step2.case1

slide19
LTM

Step3

S

S

Step2.case1

N1

N1

P

P

slide20
LTM
  • States

Case2

Case1

Case3

Step3

slide21
LTM
  • Performance
    • Traffic
    • Search scope
    • Overhead
slide22
ACE
  • Step1:
    • Probe link costs with neighbors
    • Build neighbor cost table
    • Exchange neighbors cost table with neighbors
slide23
ACE
  • Step2:
    • Create a minimum spanning tree among each peer and its neighbors

E

E

14

14

4

4

15

G

G

S

S

6

6

20

F

F

slide24
ACE
  • Step3:
    • Replace neighbors

Case1: SH<SG

E

Case2: GH>SH>SG

14

4

Case3: SH>SG,SH>GH

G

S

6

H

F

slide25
ACE
  • Depth of optimization (h-neighbor closure)

A

15

10

D

20

B

8

12

14

C

E

7

A->B=10

A->D=15

E->C=7

E->D=14

B->E=8

D->E=14

Total:68

slide26
ACE
  • 2-neighbor closure

A

A

15

10

D

D

20

B

B

8

12

14

C

E

C

E

7

A->B=10

B->E=8

E->C=7

E->D=14

Total:39

discussion
Discussion
  • Measurement
    • Link cost is not accurate
  • Link cutting and cycles
  • Heuristic to theoretical support
    • f (Pn,Tn)=?
conclusion
Conclusion
  • Importance
  • Effectiveness vs. cost
  • Future work
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