A Case for End System Multicast

1
A Case for End System Multicast

• Yang-hua Chu, Sanjay G. Rao, Srinivasan Seshan
  and Hui Zhang
• Presentation by Warren Cheung
• Some Slides from http//eeca2.sogang.ac.kr/publica
  tion/seminar/2000/EC9DB4EBAFBCED98B8/5

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Multicast

• Unicast
• Point to Point delivery
• One Host to One Client
• Multicast
• Deliver to multiple destinations
• One Host to Many Clients

3
IP vs. End System Multicast

• IP multicast
• Implemented at Internetworking layer
• Routers and switches
• End System multicast
• Implemented in the hosts and clients

4
Examples
5
Examples IP Multicast
6
Examples naive Unicast
7
Examples End System Multicast
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Considerations

• Transmission Redundancy of Data
• Unicast many copies per link
• IP Multicast one copy per link
• End System Multicast
• slightly more inefficient than IP Multicast
• Delay
• Unicast same as IP Multicast
• End System Multicast incurs penalty

9
IP multicast

• Pros
• Possibly large performance benefits
• Cons
• Needs to maintain group state
• Infrastructure level changes are slow to deploy

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End System Multicast

• Pros
• Can be implemented now
• Hosts (Peer-to-Peer)
• Proxy
• Cons
• Performance degradation

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Narada Protocol

• Self-Organising
• Constructs Overlay
• Adapt to Network/Group Dynamics
• Efficient
• Latency vs. Bandwidth
• Self-improving

12
Group Management

• Everyone keeps the member list
• Target Medium-Sized Groups
• Everyone periodically exchanges group information
  with neighbours (refresh)
• Join
• Bootstrapping
• Leave
• Partition repair

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Mesh Performance

• Mesh may be suboptimal due to
• Network conditions
• Group dynamics
• Adding random neighbours
• Dropping low cost links

14
Open Issues

• Group size on Average overlay hops
• Short-term Effects of events on Performance
• Overlay construction/maintenance costs when group
  sizes get very large

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Related Work on Overlays

• Mesh-based
• Tree-based overlays
• Delaunay Triangulations
• Map addresses to coordinate space
• Find closest neighbours
• Hierarchies of Clusters

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Related Works

• End System Multicast, Narada, Video Streaming
• http//www-2.cs.cmu.edu/esm/
• Comparison of some Application Layer Multicast
  solutions
• http//citeseer.nj.nec.com/banerjee01comparative.h
  tml

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Not-So-Closely Related Works

• BitTorrent (File Swarming)
• http//bitconjurer.org/BitTorrent/
• Herbivore (Anonymity/Security)
• http//citeseer.nj.nec.com/goel02herbivore.html

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Discussion

• IP Multicast
• Basically a failure deployment issues
• Any fundamental/low level changes to Internet
  infrastructure unlikely to succeed
• End System Multicast
• Overhead/performance impact no longer looks as
  disadvantageous as it originally appeared

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Discussion(2)

• Applications
• Limitations to video-conferencing more due to
  limitation on the number of people you can
  communicate with simultaneously
• For large number of clients, more likely to be a
  broadcast
• Narada
• Implemented and used
• Broadcasts the annual SIG networking conference