Overlay networks are virtual networks formed by cooperating nodes that
share an underlying physical network. Overlays are a flexible and
deployable approach for obtaining new network semantics without
modification of the underlying network, but they suffer from efficiency
concerns. Two new router-based primitives can help end-hosts alleviate
these inefficiencies. Packet Reflection allows end hosts to request that
routers perform routing and duplication for certain packets. Path Painting
allows end hosts to determine where their paths to a rendezvous point meet.
This knowledge facilitates building overlay topologies that resemble the
topology of the underlying network. Both primitives can be incrementally
deployed for incremental benefit.
These primitives can be used to provide an efficient application-level
multicast (ALM) system. Experimental results on simulated topologies show
that when all routers support the proposed primitives, the ALM system
incurs less than 5% overhead (in terms of link usage and latency) compared
to IP Multicast. In addition, the benefits gained are significant even at
low deployment levels. With intelligent deployment strategies, link usage
overhead is less than 30% with less than 10% deployment. Finally, these
benefits apply mostly to the area local to the deployed routers, providing
a deployment incentive to independent networks.
Dr. Jannotti is a faculty candidate.
Tuesday, March 18, 2003 at 3:00 p.m. in DH1070
Reception preceding the talk - 2:30 p.m. in DH3092