Quality of Service and Asynchronous Transfer Mode in
			   IP Internetworks

			     Bruce A. Mah
			 bmah@CS.Berkeley.EDU
		  http://http.CS.Berkeley.EDU/~bmah/

			   The Tenet Group
		      Computer Science Division
		 University of California at Berkeley

The deployment of Asynchronous Transfer Mode (ATM) networks is a
recent development in the field of computer communication.  When we
attempt to use these networks as a part of the existing global
Internet we see a number of differences between the data forwarding
models of ATM (virtual circuits supporting performance guarantees) and
IP (datagrams, usually best-effort).  In our research, we have
examined some different policies for IP-over-ATM networks to bridge
this gap and make these two types of networks function efficiently
together.

We have examined different quality of service, multiplexing, and
virtual circuit management policies, and evaluated their relative
merits from the standpoint of the performance of typical Internet
applications.  Our evaluation uses a simulation of a large IP
internetwork and a synthetic workload modeling the network traffic
sent by common Internet applications.  The results show that the use
of different scheduling algorithms and QOS parameters can be used to
express preference for (or to restrict) certain applications.  We see
that multiplexing can improve application performance due to a reduced
need to set up ATM virtual circuits, although interactions with some
network service disciplines can negate these effects.  Finally, we
show that caching idle virtual circuits for reuse is, in general,
beneficial for both network and application performance.