CS Colloquium on Wednesday, Nov. 19 at 3PM

Title: Studies on Reliable Multirate Multicast Congestion Control
       (PhD Thesis Proposal)

Speaker: Gu-In Kwon
         Boston University

Place: MCS 135, 111 Cummington Street

Abstract:

We propose new approaches to reliable multirate multicast congestion by
using the digital fountain approach.  The digital fountain approach reduces
the complexity associated with the previous approaches and enables the
reliable multirate multicast congestion control by decoupling reliability
and congestion control.  We use this benefit of the digital fountain
approach to achieve TCP-friendliness and the reliable multirate multicast
congestion control.  We consider the IP multicast congestion control and
the problem of the reliable overlay multicast congestion, which comes from
the design of tightly coupling reliability and congestion control.

Existing approaches for multirate multicast congestion control are 
either friendly to TCP only over large time scales or introduce 
unfortunate side effects, such as significant control traffic, 
wasted bandwidth, or the need for modifications to existing routers.  
We first advocate a departure from standard cumulative layering for 
multiple rate multicast.  Our approach, non-cumulative layering, 
admits the possibility of fine-grained multicast congestion control, 
which in turn enables each receiver to closely match its desired rate.

We then propose another new approach to multiple rate congestion 
control that leverages proven single rate congestion control methods 
by orchestrating an ensemble of independently controlled single rate 
sessions.  Our new scheme combines the benefits of single rate 
congestion control with the scalability and flexibility of multiple 
rates to provide a sound multiple rate multicast congestion control policy.

We also consider the problem of architecting a reliable content 
delivery system across an overlay network.  Existing approaches for 
providing both reliability and congestion control on overlay 
multicast impose fundamental performance limitation, such as 
dragging down all transfer rates in the system to the rate of the 
slowest receiver.  The ROMA architecture we propose uses fast forward 
error correction techniques to deliver a scalable solution that better 
accommodates a set of heterogeneous receivers by decoupling reliability 
and congestion control.  

Thesis Committee:

John Byers ( Advisior)
Ibrahim Matta
Azer Bestavros
Wayne Snyder