Abstract:

We describe several recent developments for improved layered multicast, generalizing and extending the receiver-driven layered congestion (RLC) control protocol introduced by Vicisano, Rizzo, and Crowcroft.

Dynamic Layering (DL) mitigates the negative impact of long IGMP leave latencies and eliminates the need for probe intervals present in RLC. Effectively DL lets our protocol respond to congestion at the order of round trip times, rather than after the potentially longer control delay for unsubscribing to a layer using the multicast routing system.

Fair Layered Increase/Decrease (FLID) generalizes the RLC protocol, ameliorating the problems associated with abrupt rate increases.

Fine-Grained Layering introduces a non-cumulative layering scheme that offers a fine-grained approximation to the behavior of TCP additive increase / multiplicative decrease (AIMD). We also provide a theoretical framework for studying the tradeoffs inherent in using non-cumulative layering.

Our improvements derive from the use of fast forward error correcting (FEC) codes, which we also describe.

Joint work with John Byers, Michael Luby, and the Digital Fountain research team.