Real-Time Commuication on Computer Networks:
	Introduction and Analisi of the Tenet Approach of Berkeley.

	From the original title (in Italian):
		Comunicazione Real-Time su Reti di Calcolatori: 
	Introduzione ed Analisi	dell'Approccio Tenet di Berkeley.
		

 	  	     Pasquale Di Genova
		
			Tesi di Laurea
		Facolta' di Ingegneria Elettronica
		Universita` di Bologna, Italia
			

 		(Department of Electrical Engineering,
	 	University of Bologna, Italy)

			December 9, 1993

        	email: digenova@tenet.Berkeley.EDU

		 
	This work was carried out at the University of 
	California at Berkeley  and at the International
	Computer Science Institute at Berkeley. 

	The thesis addresses issues related to network 
	support to multimedia applications.
	We first provide a broad background on the 
	state of the art in computer networks for
	support to multimedia applications. Bearing in mind such
	applications, we consider Local
	Area (FDDI-II and DQDB) and Wide Area (Xunet, an ATM network)
	based high-speed network architectures.
	We argue that technology is not sufficiently mature
	to support multimedia on current high-speed networks because
	congestion cannot be avoided. We consider proposed solutions
	to congestion: congestion avoidance (Internet), predicted service
	(Stanford University and MIT) and guaranteed level of service
	(University California at Berkeley). 	
	We consider the state of the art of the protocols currently 
	used (ST-II, SRP) or under development (RSVP) and compare them 
	to the Tenet protocols.
	We see to which extent multimedia applications can be
        supported on today's packet-switched networks. 
	We conclude that there is a need for a realtime service 
	model, a resource reservation model able to support 
	predefined Quality of Services to multimedia applications. 

	 This conclusions lead us to the second part of the tesis,	
	where we focus on a possible solution to providing network
	support called the Tenet Approach. This approach provides
	a more general realtime service, of which the multimedia
	service can be considered a subcase. In particular, we
	describe a transport layer protocol called Continuous 
	Media Transport Protocol (CMTP), a protocol well-suited 
	for applications which generate traffic with periodic
	characteristics such as video and audio. At this level,
	a simple algorithm has been introduced to reduce buffer
	usage. The algorithm has been implemented on a realtime 
	simulator, Galileo, developed by Edward Knightly. 
	Results show how buffer usage can be significantly reduced.
	Finally, we outline future trends in computer architectures, 
	in computer networks and in the services that they may provide.