cristian lumezanu dave levin neil spring peerwise discovery and negotiation of faster paths

Cristian LumezanuDave LevinNeil Spring

PeerWise Discovery and Negotiation of Faster Paths

Routing Overlays

PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

Deployment COST is LOWPotential BENEFIT is

HIGH

Scalability?


Probing should be done more selectivelyProbing should be done more selectively

A B

C

Routing overlays should include an incentive mechanismRouting overlays should include an incentive mechanism

Fairness?


cost

benefit

> 1

cost benefit

< 1

PeerWise


PeerWisePeerWise

Nodes that can help each other find better paths peerNodes that can help each other find better paths peer

Nodes negotiate and establish pairwise connections to each otherNodes negotiate and establish pairwise connections to each other

MotivationMotivation

Cost-benefit ratio known before committing any resourcesCost-benefit ratio known before committing any resources

Models autonomous system peerings in the InternetModels autonomous system peerings in the Internet

Overlays built on self-interest rather than altruismOverlays built on self-interest rather than altruism

PeerWise


60ms

A

B

C

D

50ms

30ms

40ms

PeerWise properties


Is mutual advantage common?


A

B

C

E

G

D

F

Difference between the number of routes each node uses the other for after all peerings have been

established

Difference between the number of routes each node uses the other for after all peerings have been

established

PEERING SCOREPEERING SCORE

• PeerWise prototype with global knowledge• 256 DNS server data set gathered using the King method• Each node sends data to all other nodes

• PeerWise prototype with global knowledge• 256 DNS server data set gathered using the King method• Each node sends data to all other nodes

EXPERIMENT SETUP

EXPERIMENT SETUP

Is mutual advantage common?


100100

10010000

74% of the pairs of nodes are happy with existing peerings74% of the pairs of nodes are happy with existing peerings

peering scorepeering score

7474

2020

PeerWise properties


Finding shorter detours


10ms 10ms

100ms

Triangle inequality violations indicate the existence of shorter one-hop detours

Triangle inequality violations indicate the existence of shorter one-hop detours

A

B

C

At least 66% of the pairs of nodes in our datasets are long sides in TIVs

At least 66% of the pairs of nodes in our datasets are long sides in TIVs

We use network coordinates to find triangle inequality violations

We use network coordinates to find triangle inequality violations

flaws in

Network coordinates and TIVs


20ms 39ms

62msA

B

C

38ms42ms

26ms

B

AC

Internet Metric space

TIVs allowedAC > AB + BC

No TIVsAC < AB + BC

error(AC) = -36ms

Long sides shrinkLong sides shrinkSum of short sides

growsSum of short sides

grows

Embedding errors and TIVs


The more negative the embedding error of an edge, the higher the probability that the edge is a long side in a TIV


The more positive the embedding error of an edge, the higher the probability that the edge is a short side in a TIV


…and thus has a one-hop shorter detour…and thus has a one-hop shorter detour

…and thus is part of a one-hop shorter detour …and thus is part of a one-hop shorter detour

If long sides shrinkIf long sides shrink

If sum of short sides growsIf sum of short sides grows

PeerWise properties


Performance


100100

00 300300

direct pathbest one-hop path

Latency (ms)Latency (ms)10

0100

PeerWise

path

PeerWise reduces latency by an average of 20%

PeerWise reduces latency by an average of 20%

Conclusions


Future Work


Why is there mutual advantage?Why is there mutual advantage?

Extensions for low-loss and failure-free pathsExtensions for low-loss and failure-free paths

Future WorkFuture Work

DeploymentDeployment

Are one-hop detours enough?


Latency (ms)Latency (ms)

100100

00 300300100100

7575

direct pathbest one-hop detour path

25% of direct paths are longer than 100ms

25% of direct paths are longer than 100ms

3% of detour paths are longer than 100ms

3% of detour paths are longer than 100ms

50% improvement in average latency

50% improvement in average latency

Connectivity


detour scoredetour score

100100

10010000 6060

4040

2222

Percentage of destinations that a node can reach using its peerings, out of all reachable

destinations

globalknowledge

limitedknowledge

(32 neighbors)

78% of nodes can reach more than 60% of their

destinations, with global knowledge


destinations, with global knowledge


destinations, with limited knowledge


destinations, with limited knowledge







…and thus has a one-hop shorter detour…and thus has a one-hop shorter detour

…and thus is part of a one-hop shorter detour …and thus is part of a one-hop shorter detour

Percentage of how many times a pair of nodes forms a long side in a TIV out of total number of presences in

TIVs

Percentage of how many times a pair of nodes forms a long side in a TIV out of total number of presences in

TIVs

TIV SCORETIV SCORE



00-200-200 200200embedding errorembedding error

00

100100

5050

As the estimation error becomes more negative the nodes form more and more

long sides

As the estimation error becomes more negative the nodes form more and more

long sides

estimated distance – real distance

morelongsides

moreshortsides

cristian lumezanu dave levin neil spring peerwise discovery and negotiation of faster paths

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