A Case for End System A Case for End System MulticastMulticast

Yang-hua Chu, Sanjay G. Rao, Srinivasan Yang-hua Chu, Sanjay G. Rao, Srinivasan Seshan and Hui ZhangSeshan and Hui Zhang

Presentation by Warren CheungPresentation by Warren Cheung

Some Slides from Some Slides from http://eeca2.sogang.ac.kr/publication/seminahttp://eeca2.sogang.ac.kr/publication/semina

r/2000/%EC%9D%B4%EB%AF%BC%EDr/2000/%EC%9D%B4%EB%AF%BC%ED%98%B8/5%98%B8/5

MulticastMulticast

Unicast:Unicast:– Point to Point delivery Point to Point delivery – One Host to One ClientOne Host to One Client

Multicast:Multicast:– Deliver to multiple destinationsDeliver to multiple destinations– One Host to Many ClientsOne Host to Many Clients

IP vs. End System MulticastIP vs. End System Multicast

IP multicastIP multicast– Implemented at Internetworking layerImplemented at Internetworking layer

Routers and switchesRouters and switches

End System multicastEnd System multicast– Implemented in the hosts and clientsImplemented in the hosts and clients

ExamplesExamples

Examples – IP MulticastExamples – IP Multicast

Examples – naive UnicastExamples – naive Unicast

Examples – End System MulticastExamples – End System Multicast

ConsiderationsConsiderations

Transmission Redundancy of DataTransmission Redundancy of Data– Unicast: many copies per linkUnicast: many copies per link– IP Multicast: one copy per linkIP Multicast: one copy per link– End System Multicast:End System Multicast:

slightly more inefficient than IP Multicastslightly more inefficient than IP Multicast

DelayDelay– Unicast same as IP MulticastUnicast same as IP Multicast– End System Multicast incurs penaltyEnd System Multicast incurs penalty

IP multicastIP multicast

ProsPros– Possibly large performance benefitsPossibly large performance benefits

ConsCons– Needs to maintain “group state”Needs to maintain “group state”– Infrastructure level changes are slow to Infrastructure level changes are slow to

deploydeploy

End System MulticastEnd System Multicast

ProsPros– Can be implemented nowCan be implemented now

Hosts (Peer-to-Peer) Hosts (Peer-to-Peer) ProxyProxy

ConsCons– Performance degradationPerformance degradation

Narada ProtocolNarada Protocol

Self-OrganisingSelf-Organising– Constructs OverlayConstructs Overlay– Adapt to Network/Group DynamicsAdapt to Network/Group Dynamics

EfficientEfficient– Latency vs. BandwidthLatency vs. Bandwidth– Self-improvingSelf-improving

Group ManagementGroup Management

Everyone keeps the member listEveryone keeps the member list– Target Medium-Sized GroupsTarget Medium-Sized Groups– Everyone periodically exchanges group Everyone periodically exchanges group

information with neighbours (refresh)information with neighbours (refresh) JoinJoin– BootstrappingBootstrapping

LeaveLeave– Partition repairPartition repair

Mesh PerformanceMesh Performance

Mesh may be suboptimal due to:Mesh may be suboptimal due to:– Network conditionsNetwork conditions– Group dynamicsGroup dynamics

Adding random neighboursAdding random neighbours

Dropping low “cost” links Dropping low “cost” links

Open IssuesOpen Issues

Group size on Average overlay hopsGroup size on Average overlay hops

Short-term Effects of events on Short-term Effects of events on PerformancePerformance

Overlay construction/maintenance Overlay construction/maintenance costs when group sizes get very costs when group sizes get very largelarge

Related Work on OverlaysRelated Work on Overlays

Mesh-basedMesh-based Tree-based overlaysTree-based overlays

Delaunay TriangulationsDelaunay Triangulations– Map addresses to coordinate spaceMap addresses to coordinate space– Find closest neighboursFind closest neighbours

Hierarchies of ClustersHierarchies of Clusters

Related WorksRelated Works

End System Multicast, Narada, Video End System Multicast, Narada, Video StreamingStreaming– http://www-2.cs.cmu.edu/~esm/http://www-2.cs.cmu.edu/~esm/

Comparison of some Application Comparison of some Application Layer Multicast solutionsLayer Multicast solutions– http://citeseer.nj.nec.com/http://citeseer.nj.nec.com/

banerjee01comparative.htmlbanerjee01comparative.html

Not-So-Closely Related WorksNot-So-Closely Related Works

BitTorrent (File Swarming)BitTorrent (File Swarming)– http://bitconjurer.org/BitTorrent/http://bitconjurer.org/BitTorrent/

Herbivore (Anonymity/Security)Herbivore (Anonymity/Security)– http://citeseer.nj.nec.com/http://citeseer.nj.nec.com/

goel02herbivore.htmlgoel02herbivore.html

DiscussionDiscussion

IP MulticastIP Multicast– Basically a failure – deployment issuesBasically a failure – deployment issues– Any fundamental/low level changes to Any fundamental/low level changes to

Internet infrastructure unlikely to Internet infrastructure unlikely to succeedsucceed

End System MulticastEnd System Multicast– Overhead/performance impact no longer Overhead/performance impact no longer

looks as disadvantageous as it originally looks as disadvantageous as it originally appearedappeared

Discussion(2)Discussion(2)

ApplicationsApplications– Limitations to video-conferencing more Limitations to video-conferencing more

due to limitation on the number of people due to limitation on the number of people you can communicate with simultaneouslyyou can communicate with simultaneously

– For large number of clients, more likely to For large number of clients, more likely to be a broadcastbe a broadcast

NaradaNarada– Implemented and usedImplemented and used– Broadcasts the annual SIG networking Broadcasts the annual SIG networking

conferenceconference