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Multicast Service Overlay Design

Multicast Service Overlay Design. Li Lao (UCLA), Jun-Hong Cui (UCONN) , Mario Gerla (UCLA). Multicast Overview. IP Multicast. Application Layer Multicast. Overlay Multicast. Multicast Overview. IP multicast (network level, routers) Efficient Faces deployment and marketing problems

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Multicast Service Overlay Design

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  1. Multicast Service Overlay Design Li Lao (UCLA), Jun-Hong Cui (UCONN), Mario Gerla (UCLA)

  2. Multicast Overview IP Multicast Application Layer Multicast Overlay Multicast SPECTS 2005

  3. Multicast Overview • IP multicast (network level, routers) • Efficient • Faces deployment and marketing problems • Application layer multicast (end hosts) • Easy to deploy • Inefficient and difficult to scale to large groups • Multicast Service Overlay Network (MSON)(proxies) • Efficient and scale to large groups • Need careful overlay design • A Comparative Study of Multicast Protocols: Top, Bottom, or In the Middle? (Lao, et al. GI 2005) SPECTS 2005

  4. An Example of MSON TOMA F MSON D C E B A Application-Layer Multicast SPECTS 2005

  5. Our Goal • Investigate MSON provisioning • Where to place proxies • How to connect these proxies (overlay links) • How much bandwidth to be reserved on each overlay link • Examine effects of design algorithms • Performance of TOMA (as example) SPECTS 2005

  6. An Example of MSON Design D A E I SPECTS 2005

  7. Roadmap • Motivation • Problem Formulation • Our Approach • Simulation Study • Conclusion SPECTS 2005

  8. Problem Formulation • Input: a network N = (V, E), multicast groups G with membership distribution and bandwidth requirement • Output: a virtual network N’ = (V’, E’) • V’ V, and E’ path(E) • Each e’is assigned bandwidth, e’E’ • Objective: minimize multicast overlay cost and average end-to-end delay SPECTS 2005

  9. Our Approach Divide and Conquer • Overlay proxy placement: determine V’ • Overlay link selection: determine E’ • Bandwidth dimensioning: determine bandwidth for e’E’ SPECTS 2005

  10. 1. Overlay Proxy Placement • Given: the number of members wi for each router i (1  in), and the shortest distance dij between every two routers i and j • Find: no more than K (1 K  n) routers as proxies • Objective: the weighted sum of distances from each router to its nearest proxy is minimized SPECTS 2005

  11. Solution • ILP Formulation • A lot of approaches to solve, but expensive • Greedy • In each step, a router i is selected if this reduces the weighted sum of distances by the largest amount • O(Kn2) SPECTS 2005

  12. E E C A C A D D B B E E C C A A D D B B 2. Overlay Link Selection Complete Graph 1-MST Adjacent Connection SPECTS 2005

  13. Solutions • Complete Graph • Shortest path length • Highest tree cost • Largest number of overlay links: • Adjacent Connection • Shortest path length • Reduced tree cost • Reduced number of overlay links • Minimum Spanning Tree • Long path length • Minimum tree cost • Minimum number of overlay links: SPECTS 2005

  14. 3. Bandwidth Dimensioning • Given: an overlay network N’ = (V’, E’), a set of groups G with member distribution and bandwidth requirements, and a multicast routing algorithm • Compute the amount of bandwidth reserved on each overlay link e’ E’ SPECTS 2005

  15. Solution • Simulation-based approach • Compute the multicast trees • Sum up the traffic volume of these trees for each overlay link • Over-dimensioning SPECTS 2005

  16. Simulation Study • Abstracted AT&T backbone • 54 nodes, 9 proxies • Weight-based membership model • Rocketfuel 1755 • ~300 nodes, 20 proxies • Uniform membership distribution • Metrics • Multicast tree cost, path length, request rejection ratio SPECTS 2005

  17. Overlay Proxy Placement SPECTS 2005

  18. Overlay Proxy Placement SPECTS 2005

  19. Overlay Link Selection SPECTS 2005

  20. Bandwidth Dimensioning SPECTS 2005

  21. Bandwidth Dimensioning SPECTS 2005

  22. Conclusions & On-going Work • Formulated the problem and divided it into three sub-problems • Proposed solutions to each sub-problem • Greedy algorithm very effective for overlay proxy placement • MST and Adjacent Connection perform better than Complete Graph • Over-dimensioning is needed for bandwidth dimensioning to reduce join request rejection ratio • On-going work: • Overlay link selection: trade-off of overlay cost and delay • Probe a comprehensive optimal approach SPECTS 2005

  23. Questions ??? Thank you! SPECTS 2005

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