1 / 14

Communication Part IV Multicast Communication*

Communication Part IV Multicast Communication*. *Referred to slides by Manhyung Han at Kyung Hee University and Hitesh Ballani at Cornell University. Unicast, Broadcast versus Multicast. Key: Unicast transfer Broadcast transfer Multicast transfer. Unicast One-to-one

raisie
Download Presentation

Communication Part IV Multicast Communication*

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Communication Part IV Multicast Communication* *Referred to slides by Manhyung Han at Kyung Hee University and Hitesh Ballani at Cornell University

  2. Unicast, Broadcast versus Multicast Key: Unicast transfer Broadcast transfer Multicast transfer • Unicast • One-to-one • Destination – unique receiver host address • Broadcast • One-to-all • Destination – address of network • Multicast • One-to-many • Multicast group must be identified • Destination – address of group

  3. Multicast application examples • Financial services • Delivery of news, stock quotes, financial indices, etc • Remote conferencing/e-learning • Streaming audio and video to many participants (clients, students) • Interactive communication between participants • Data distribution • e.g., distribute experimental data from Large Hadron Collider (LHC) at CERN lab to interested physicists around the world

  4. Routers with multicast support IP multicast Gatech Stanford CMU Berkeley • Highly efficient bandwidth usage • Key Architectural Decision: Add support for multicast in IP layer

  5. So what is the big issue … more than 20 years since proposal, but no wide area IP multicast deployment • Scalability (with number of groups) -- Routers maintain per-group state • IP Multicast: best-effort multi-point delivery service -- Providing higher level features such as reliability, congestion control, flow control, and security has shown to be more difficult than in the unicast case Can we achieve efficient multi-point delivery without IP-layer support?

  6. Application layer multicast Stan1 Gatech Stanford Stan2 CMU Berk1 Berkeley Berk2 Overlay Tree Stan1 Gatech Stan2 CMU Berk1 Berk2

  7. Pros and Cons • Scalability • Routers do not maintain per-group state • End systems do, but they participate in very few groups • Potentially simplify support for higher level functionality • Leverage computation and storage of end systems • Leverage solutions for unicast congestion, error and flow control • Efficiency concerns • redundant traffic on physical links • increase in latency due to end-systems

  8. System structure The overlay comprises of : • A central source (may be replicated for fault tolerance) • A number of overcast nodes (standard PCs with lot’s of storage) - organized into a distribution tree rooted at the source - bandwidth efficient trees • Final Consumers – members of the multicast group - allows unmodified HTTP clients to join

  9. R 1 R R R 1 2 2 1 2 Bandwidth Efficient Overlay Trees 1 100 Mb/s 10 Mb/s 100 Mb/s 2

  10. R R 1 2 3 The node addition algorithm 5 10 10 3 8 1 7 5 2 Physical network substrate Overcast distribution tree

  11. The client side – how to join a multicast group • Clients join a multicast group through a typical HTTP GET request • Root determines where to connect the client to the multicast tree using • Status of overcast nodes • Location of client • Root selects “best” server and redirects the client to that server

  12. R1 R2 R3 1 3 2 4 5 6 Client Joins Key: Content query (multicast join) Query redirect Content delivery

  13. Application level multicasting A survey on ALM

More Related