canon in g major: designing dhts with hierarchical structure prasanna ganesan(stanford university)...
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![Page 1: Canon in G Major: Designing DHTs with Hierarchical Structure Prasanna Ganesan(Stanford University) Krishna Gummadi(University of Washington) Hector Garcia-Molina(Stanford](https://reader035.vdocuments.net/reader035/viewer/2022062802/56649eac5503460f94bb32f7/html5/thumbnails/1.jpg)
Canon in G Major: Designing DHTs with Hierarchical Structure
Prasanna Ganesan(Stanford University)Krishna Gummadi(University of Washington)
Hector Garcia-Molina(Stanford Universiy)
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Motivating Scenario
• P-2-P Application– File sharing– Multi-media sharing– Collaborative computation– General purpose lookup directories
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Motivating Scenario
Where is the paper “Canon in G Major”?
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Hierarchy Design
EE CSCS BIO
KAIST Stanford
Engineering School
Single Point
Over Head
Isolating faultsAdapting growth
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Flat Design(DHT)
No single point of failure
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Flat & Hierarchical Design
• Flat Design– No single point of failure– P2P(DHT)
• Hierarchical Design– Isolating faults– Adapting growth– DNS
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Canonical System
EE CSCS BIO
KAIST Stanford
Engineering School
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Crescendo
Chord Chord
Merged Chord
EECS
KAIST
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Chord
• Circular N-bit ID space
• Node x links to succ(x+2^i)
0
5
12
1
3
7
8
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Crescendo
• Merge– Merging multiple rings– Multi-level hierarchies
• Incremental– New node joins bottom up
• Links per node– Log(n)
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Merging
10
0
5
12
8
3
2
13
0
5
12
8
3
2
13
10
0
5
12
8
3
2
13
10
0
5
12
8
3
2
13
10
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Merging
• Merging Rule– Closer than any other black node– Y=succ(x+2^i)
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Routing Crescendo(intra-domain)
10
0
5
12
Greedy Clockwise routing
Path Locality-Fault isolation-Security-Efficiency
0 -> 12
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Routing Crescendo(inter-domain)
10
0
5
12
0
5
12
8
3
2
13
10
0
5
12
10
Path convergence:closest node to destination in the domain:same destination node same last node in the domain
0 -> 13
-Distributed Caching
-Bandwidth savings
0
5
12
8
3
2
13
10
5 -> 13
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Other DHTs
• Chord => Crescendo• CAN => Can-Can• Symphony => Cacophony• Kademlia => Kandy
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Evaluation
• Links/node• Hops/query• latency
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Number of Links vs. Number of Levels
9
10
11
12
13
14
15
16
17
1000 10000 100000
Number of Nodes
Nu
mb
er o
f L
inks
Chord
Levels=2
Levels=3
Levels=4
Levels=5
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Levels vs. Routing Hops
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
1000 10000 100000
Number of Nodes
Nu
mb
er o
f H
op
s
Chord
Levels=2
Levels=3
Levels=4
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Path Locality
0
100
200
300
400
500
600
700
800
900
1000
Top First Second Third Fourth
Query Locality
Lat
ency
(m
s)
Chord (Prox.)
Crescendo
Crescendo (Prox.)
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Critique
• Strong point– Novel Idea– Good development of idea
• Weak point– Poor motivating scenario
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New Idea
• Do you have any New Idea?