PeerWise Discovery and Negotiation of Faster Paths

Cristian Lumezanu Dave Levin Neil Spring

Routing Overlays

Potential BENEFIT is HIGH Deployment COST is LOW PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

Scalability?

A C B Probing should be done more selectively PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

Fairness?

cost

benefit > 1 cost

benefit

< 1 Routing overlays should include an incentive mechanism PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

PeerWise

PeerWise Nodes negotiate and establish pairwise connections to each other Nodes that can help each other find better paths peer Motivation Models autonomous system peerings in the Internet Overlays built on self-interest rather than altruism Cost-benefit ratio known before committing any resources PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

PeerWise

D 30ms 50ms A B 40ms 60ms C

PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

PeerWise properties

PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

PeerWise properties

PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

Is mutual advantage common?

G E B D F

PEERING SCORE

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

EXPERIMENT SETUP

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

PeerWise Discovery and Negotiation of Faster Paths

C

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Is mutual advantage common?

100 74

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

0  20 peering score

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PeerWise properties

PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

Finding shorter detours

B 10ms 10ms

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

A C 100ms

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

flaws in

We use network coordinates to find triangle inequality violations PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

20ms

Network coordinates and TIVs

B 39ms Internet Metric space 38ms B 42ms A 62ms

TIVs allowed AC > AB + BC

C C A 26ms

error(AC) = -36ms No TIVs AC < AB + BC Long sides shrink Sum of short sides grows PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

Embedding errors and TIVs

If long sides shrink The more negative the embedding error of an edge, the higher the probability that the edge is a long side in a TIV …and thus has a one-hop shorter detour If sum of short sides grows 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 is part of a one-hop shorter detour PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

PeerWise properties

PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

Performance

best one-hop path

100

direct path PeerWise reduces latency by an average of 20%

0 100 Latency (ms)

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Conclusions

PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

Future Work

Future Work Why is there mutual advantage?

Extensions for low-loss and failure-free paths Deployment PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

Are one-hop detours enough?

100 75

best one-hop detour path direct path 3% of detour paths are longer than 100ms 25% of direct paths are longer than 100ms 50% improvement in average latency

0 100 Latency (ms)

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Connectivity

100

60% of nodes can reach more than 60% of their destinations, with limited knowledge limited knowledge (32 neighbors) global knowledge

40 22 0 detour score 60 Percentage of destinations that a node can reach using its peerings, out of all reachable destinations

78% of nodes can reach more than 60% of their destinations, with global knowledge

100

PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

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

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

PeerWise Discovery and Negotiation of Faster Paths HotNets 2007

more long sides

Embedding errors and TIVs

100

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

50

more short sides

0 -200 0 embedding error estimated distance – real distance

PeerWise Discovery and Negotiation of Faster Paths

200

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