Multicast Routing

Concept: Single Source, Multiple Destinations, Duplication only at branch points.

Present Day Support:

• Communication satellites.
• e-mail lists, internet news distribution. 

Tomorrow's multimedia applications require:

• efficient use of bandwidth. 
• near simultaneous delivery.

Applications: Multicast & Multi-point

One to Many

• Video Distribution
• Wide scale Information dissemination.

Many to Many

• Video Conferencing
• Computer Supported Common Work.
• Distributed interactive simulation.
• Large scale distributed (super)computing.
• Distributed Games

Advantages

• SRSPTs are easy to compute. Use the classic unicast routing tables.
• Efficient distributed implementations are possible
• Entire global topology not required.
• There can be no loops in the path returned.

Disadvantages

• Does not minimize total cost of distribution
• Does not scale well.
• One piece of state information per source and per group is kept in each router.
• May fail badly if the underlying unicast routing is asymmetric.