MPhil Thesis Defence


"SALM: An Efficient Application-level Multicast Protocol for Dynamic
Groups"

By

Mr. Wan Ching Wong


Abstract

Applications such as Internet-TV and software distribution often require
multicast for their delivery. As of today, IP multicast still experiences
difficulty in commercial deployment. To address it, researchers have
shifted their focus to "application-level multicast" (ALM), where the
multicast-related functionalities are moved to end-hosts. ALM builds an
overlay topology consisting of end-to-end unicast connections between
end-hosts.  In this thesis, we first describe the basic mechanism of
several representative ALM protocols, namely, Narada, Delaunay
Triangulation, NICE and Scribe. Using Internet-like topologies, we then
compare their performance in terms of network stress, stretch, and
overhead incurred.

We also propose a distributed ALM protocol for applications such as stock
quotes, where users may hop from one multicast group to another
frequently, even through the total pool of end-hosts in the system may be
more static. Our protocol efficiently maintains multiple multicast trees
for these dynamic subsets of end-hosts, and hence is called subset-ALM
(SALM). SALM first builds a mesh based on Delaunay Triangulation (DT)
consisting of all end-hosts for control messaging. The mesh supports
continuous addition and deletion of end-hosts in the system, and is used
to efficiently guide the construction of dynamic overlay trees.  Our
constructed trees not only have low maintenance cost, but also provide QoS
by delegating paths and limiting end-host fanouts.  We study two ways of
tree construction depending on whether or not the tree branches are
embedded in the mesh edges (embedded versus bypass trees). We show that a
bypass tree in general performs better, and SALM achieves low costs in
terms of relative delay penalty and physical link stress, even for large
multicast groups.


Date:			Monday, 4 August 2003

Time:			3:00p.m.-5:00p.m.

Venue:			Room 1505
			Lifts 25-26

Committee Members:		Dr. Gary Chan (Supervisor)
			Dr. Jogesh Muppala (Chairman)
			Prof. Lionel Ni



**** ALL are Welcome ****