Eliminating Bottlenecks in Overlay Multicast Min Sik Kim Yi Li - PowerPoint PPT Presentation

Eliminating Bottlenecks in Overlay Multicast Min Sik Kim Yi Li Simon S. Lam Department of Computer Sciences The University of Texas at Austin

Overlay Multicast IP multicast overlay multicast N unicast Bottleneck  How to construct an efficient overlay tree? 2

Eliminating Shared Bottlenecks 1 1 2 2 4 4 3 3 5 5  Shared congestion detection  Bottleneck Elimination  Why difficult? 3

Outline  Introduction  Types of Shared Bottlenecks  Bottleneck Elimination  Performance Evaluation  Summary 4

Inter-path Shared Bottleneck u 1 u 2 u 1 v 1 u 2 v 1 v 2 v 2 5

Intra-path Shared Bottleneck u 1 u 2 u 1 v 1 u 2 v 1 v 2 v 2 6

Algorithm  Eliminate both types of shared bottlenecks  No tree oscillation Remove a shared bottleneck … Tree 1 Tree 2 Tree 3 Tree N  One-way process  Finite steps 7

Example 1 1 2 3 4 2 4 3  # of leaves ↓  Height ↑ 8

Leaf Distance Vector  Depths of all leaf nodes in descending order 1 1 2 3 4 2 4 3 D = (1,1,1) D = (2,1) � 9

Total Cost  Sum of costs of all edges in the tree u 2 u 1 u 2 u 1 1 1 1 1 1 1 1 1 1 1 1 1 v 1 v 1 v 2 v 2 C = 3 + 1 + 3 = 7 > C = 2 + 1 + 2 = 5 � u 1 v 1 v 1 u 2 u 2 v 2 u 1 u 2 u 2 v 1 v 1 v 2 10

Proof Sketch  Bottleneck elimination algorithms  Remove-Inter-Path-Shared-Bottleneck  Remove-Intra-Path-Shared-Bottleneck  Applying either algorithm causes  D ↑  C ↓  Only a finite # of changes 11

Protocol  Measure delay for u 1 congested edges  Detect shared congestion v 1  Eliminate shared bottlenecks  Forward remaining u 2 bottlenecks v 2 12

Performance Evaluation  Comparison  Delay heuristic  Bandwidth heuristic  Bottleneck-free  Metrics  Links stress  Link load  Relative delay penalty  Receiving rate 13

Link Stress 14

Link Load 15

Receiving Rate 16

Relative Delay Penalty 17

Summary  Overlay multicast creates shared bottlenecks  Proposed tree construction algorithm  Eliminates all shared bottlenecks  Provides full receiving rate  Low link load, low delay 18