Cristian Lumezanu Dave Levin Neil Spring PeerWise Discovery and Negotiation of Faster Paths.
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Transcript of Cristian Lumezanu Dave Levin Neil 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?
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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?
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
cost
benefit
> 1
cost benefit
< 1
PeerWise
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
60ms
A
B
C
D
50ms
30ms
40ms
Is mutual advantage common?
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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?
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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
Finding shorter detours
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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 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
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
Performance
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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%
Future Work
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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?
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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
78% of nodes can reach more than 60% of their
destinations, with global knowledge
60% of nodes can reach more than 60% of their
destinations, with limited knowledge
60% of nodes can reach more than 60% of their
destinations, with limited knowledge
Embedding errors and TIVs
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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 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
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
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
Embedding errors and TIVs
PeerWise Discovery and Negotiation of Faster Paths HotNets 2007
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