lec-32 - Multicast Protocols IGMP DVMRP PIM-DM PIM-SM...

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6 Nov 2008  BITS C481 (Computer Networks) 1 Multicast Protocols IGMP DVMRP PIM-DM PIM-SM Challenges in multicasting…….? 1. How can a sender restrict who can receive? 2. Need authentication, authorization 3. Encryption of data 4. Key distribution 5. Still an active area of research
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6 Nov 2008  BITS C481 (Computer Networks) 2 Getting Packets to End Hosts Packets from remote sources will only be forwarded by IP routers onto a local network only if they know there is at least one recipient for that group on that network Internet Group Management Protocol ( IGMP , RFC2236) Used by end hosts to signal that they want to join a specific multicast group Used by routers to discover what groups have interested member hosts on each network to which they are attached. Implemented directly over IP
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6 Nov 2008  BITS C481 (Computer Networks) 3 IGMP – Joining a group Example : R joins to Group 224.2.0.1 R sends IGMP Membership-Report to 224.2.0.1 DR receives it. DR will start forwarding packets for 224.2.0.1 to Network A DR periodically sends IGMP Membership-Query to 224.0.0.1 (ALL-SYSTEMS.MCAST.NET) R answers IGMP Membership- Report to 224.2.0.1 R R: Receiver DR: Designated Router Data to 224.2.0.1 IGMP Membership- Report Network A Network B DR
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6 Nov 2008  BITS C481 (Computer Networks) 4 IGMP – Leaving a group Example : R leaves from a Group 224.2.0.1 R sends IGMP Leave-Group to 224.0.0.2 (ALL-ROUTERS.MCAST.NET) DR receives it. DR stops forwarding packets for 224.2.0.1 to Network A if no more 224.2.0.1 group members on Network A. Data to 224.2.0.1 R DR R: Receiver DR: Designated Router IGMP Leave-Group Network A Network B
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6 Nov 2008  BITS C481 (Computer Networks) 5 IP multicast routing Routing protocols are used in conjunction with IGMP Distribution tree structure Source tree More memory O (G x S ) in routers Optimal path from source to receiver, minimizes delay Good for small number of senders, many receivers such as Radio broadcasting application Shared tree Less memory O (G) in routers Sub-optimal path from source to receiver, may introduce extra delay (source to root) May have duplicate data transfer (possible duplication of a path from source to root and a path from root to receivers) Good for Environments where most of the shared tree is the same as the source tree Many senders with low bandwidth (e.g. shared whiteboard)
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6 Nov 2008  BITS C481 (Computer Networks) 6 Protocol types Dense mode protocols assumes dense group membership Source distribution tree DVMRP (Distance Vector Multicast Routing Protocol)
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This note was uploaded on 07/20/2009 for the course CONPUTER S BITS C481 taught by Professor Prof.virendersinghshekhawat during the Fall '08 term at Birla Institute of Technology & Science, Pilani - Hyderabad.

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lec-32 - Multicast Protocols IGMP DVMRP PIM-DM PIM-SM...

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