Subject: Recent and current research by the Tenet Group at UCBerkeley and ICSI

From: [email-masked] (Domenico Ferrari)
Date: Tue, 4 May 93 17:48:26 PDT

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\fBThe Tenet Group\fR
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University of California, Berkeley
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and International Computer Science Institute
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\fBRecent and Current Research\fR
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April 1993
.sp 2
.NH 1
Introduction
.PP
The Tenet Group was formed in September of 1989 at the University of 
California at Berkeley and the International Computer Science Institute 
(ICSI, also in Berkeley) 
to perform research in high-speed computer networking. 
The focus of the group is on the design
and development of 
real-time communication services, 
and on network support for continuous-media applications. 
.PP
The Tenet Group is participating in
two major multi-institution research projects: BLANCA and Sequoia 2000.
The BLANCA project is part of the Gigabit Testbed Initiative,
which is sponsored by the Corporation for National Research Initiatives
and supported by the National Science Foundation and by the Defense Advanced
Research Projects Agency.
The BLANCA project officially started in May 1990 and currently includes
AT&T Bell Laboratories, the universities of California, Illinois, and
Wisconsin, Pacific Bell, and a few research institutes, among which is ICSI. 
The goal of BLANCA is to design and build two wide-area ATM-based testbeds called 
Xunet 2 (at 45 Mbps) and Xunet 3 (at 622 Mbps), and demonstrate on them several 
applications requiring high-speed networking.
Most of applications are of the scientific visualization type, 
and require the transmission of image sequences and/or video streams.
The sequences or streams are to be browsed, stopped, and played
forward or backward at speeds slower or faster than the nominal
one, by scientists at sites far from those where the sequences
or streams are generated or stored.
.PP
Sequoia 2000, the second major initiative in which the Tenet Group is
participating, aims at building high-speed storage and communication
facilities for global-change scientists at remote locations to visualize and
browse sequences of digitally represented satellite maps
and other large sets of data to be used in earth science research.
Project Sequoia 2000, the sequel to Project Athena,
was awarded in July 1991 by the Digital Equipment Corporation
to the University of California system; its network design and research
activities are taking place at U.C. Berkeley and U.C. San Diego.
The Sequoia 2000 network (S2Knet) connects at T1 speed the 
Berkeley campus to the Davis, Santa Barbara, 
Los Angeles, and San Diego campuses, as well as to the Scripps
Institution of Oceanography in San Diego and the State's Department of Water
Resources near Sacramento.
The network's bandwidth will be increased to 45 Mbps in July 1993.
.PP
The contributions of the Tenet Group
to both projects are concerned primarily with the
technological foundations, rather than with the end-user
applications, and can be classified into two partially
overlapping areas: (a) real-time communication services, and
(b) continuous-media networking applications.
.NH 1
Real-Time Communications Services
.NH 2
The prototype Tenet real-time protocol suite (Suite 1)
.LP
.B
Protocol implementation.\ \ 
.R
\fBHui Zhang\fR has been continuing his work on RMTP/RTIP. 
Progress has
been made in two areas:\ \  
(1) RMTP/RTIP is more stable, 
and 
(2) RCAP and RMTP/RTIP have been integrated, 
so that applications can use RCAP to establish connections 
and RMTP/RTIP to transfer data.
\fBHui Zhang\fR has also been continuing his research on service disciplines.
A new mechanism called stand-by queue 
has been proposed within the framework
of the Rate-Controlled Static Priority Queueing Discipline 
to provide better performance for non-real-time traffic.  
Extensive simulation experiments have been performed 
to study the tradeoffs between 
rate-jitter control and delay-jitter control, 
and between the work-conserving and non-work-conserving
versions of RCSP.
\fBAnindo Banerjea\fR and \fBBruce Mah\fR have 
completed the development of
the Real-Time Channel Administration Protocol 
and integrated it
with the Real-Time Internet Protocol 
on a local area testbed based on FDDI rings. 
They are currently running experiments on this testbed. 
RCAP has also been deployed 
on the 
S2Knet
testbed. 
Experiments to measure the performance of RTIP 
and compare them to the guarantees promised 
by RCAP are being planned.
\fBAmit Gupta\fR 
and
\fBAnindo Banerjea\fR 
are integrating CMTP with RCAP.
.sp .5
.LP
.B
Porting the Tenet suite to the Xunet 3 testbed.\ \ 
.R
The Berkeley branch of Xunet 3 will initially be
a HIPPI-only testbed;
it will be partially converted to an ATM testbed
when the necessary HIPPI-ATM conversion board
will be available for use.
Serial HIPPI connectivity using the 
BCP HIPPI extenders has already been established 
between Cory and Evans Halls on the UC Berkeley campus 
and Building 50 at Lawrence Berkeley Laboratory.  
\fBBruce Mah\fR 
and his coworkers in the RAID Group and at LBL
have done some testing using IP 
to verify connectivity over the fiber paths 
and through the HIPPI switches.
Due to the nature of the filesystem code on RAID II, 
they have discovered that the RAID II/Sprite port 
of the Real-Time Channel Administration Protocol (RCAP) 
will involve slightly more work than simple recompilation.  
In particular, 
it will require a new interface
to the filesystem code within the Sprite kernel.  
The different design alternatives
are being investigated.  
This work is expected to open up 
new implementation possibilities for future
RCAP implementations under UNIX.
\fBTom Fisher\fR has taken the currently stable versions 
of the Real-Time Message Transport Protocol (RMTP) 
and the Real-Time Internet Protocol (RTIP), 
which have previously been developed 
to run on DECstation 5000s under Ultrix4.2, and 
has further developed them to operate 
on Sun SPARC machines under SunOS-4.1.X. 
This work has included: 1) the separation of the machine-dependent parts of 
the kernel source code for the protocols into a clearly defined module; 2) the
development of a clear and uniform system of four separate levels of debugging 
messages to allow common users (having no kernel knowledge) to understand
when and where (and in some cases why) things go wrong; and 
3) the initial steps toward making RTIP device-driver-independent,
thus allowing it to be installed 
on systems where device driver source code 
is not available.
.sp .5
.LP
.B
Porting the Tenet suite to the S2Knet testbed.\ \ 
.R
\fBFred Templin\fR 
ported RTIP to the S2Knet routers,
and 
established the Sequoia kernel source pool 
to create a common kernel build area 
for the Tenet protocols 
as well as other Sequoia kernel changes. 
To facilitate Tenet Group research on the S2Knet testbed,
\fBTemplin\fR has created a framework 
for running Tenet network experiments. 
He is working with other members of the Tenet Group 
to test and verify the operation of 
RMTP/RTIP and RCAP across various paths of the S2Knet, 
and 
to measure the performance of these protocols on that network.
.sp .5
.LP
.B
Introducing real-time features into Ultrix.
.R
\fBTom Fisher\fR has continued his work on the development of real-time process
scheduling in the Ultrix4.2 kernel.  The current status of his work can be
described as that of discovering and solving bugs one at a time.  Because of 
the critical nature of this work (preempting and suspending, at fixed locations,
processes executing in an otherwise unpreemptible kernel), unpredictable and
non-deterministic problems have been observed.  For example, at some time,
the modified real-time kernel may support real-time processing for up to 12
hours without any conspicuous problem, while at other times the mean time
between failures is only a few minutes.  As a result, it is currently
the focus of Fisher's work to determine when and where these problems arise and
to solve them one at a time.  
The process of discovering the cause of a particular 
failure includes determining which preemption point had last been used, 
and which locks (if any) were being held by the preempting process as well as
by the processes being suspended.  
The successive elimination of failures has 
so far consisted of adding more locks (both dynamic and static) 
on data structures, and 
in some cases either to remove or to relocate the suspected preemption point.
.sp .5
.LP
.B
A simulator for networks offering real-time services.\ \ 
.R
\fBEdward Knightly\fR and \fBGiorgio Ventre\fR have finished several aspects 
of their work on Galileo, 
a tool for analysis 
and simulation of real-time communication networks and protocols. 
Currently, 
Galileo shows the effects of the network 
on a transmitted video stream. 
It displays a "before" and an "after" video stream 
providing a qualitative analysis of the delay, 
delay-jitter, 
and loss rate received by a simulated video connection. 
In another aspect of simulation, 
the design is complete for interfacing the simulator directly 
to the actual network. 
For example, 
if a client wishes to set up a video conference 
with another host on the network, 
Galileo will read the actual RCAP information 
on the current state of the network,
and, with this information, 
will simulate the proposed video connection.
.NH 2
The next Tenet scheme (Scheme 2) and suite (Suite 2)
.PP
Work is progressing on developing Scheme 2, 
which is the scheme for real-time communication 
on which the next Tenet suite (Suite 2) will be based.
The key 
features being considered for inclusion in Scheme 2 are
a new model for the client-service interface, 
real-time multicast channels,
advance reservations of real-time channels, 
mechanisms 
for supporting multiple virtual real-time networks, 
dynamic channel management, the channel group abstraction,
and fault recovery.
The group discussing the different aspects of
Scheme 2 design
is led by 
\fBDomenico Ferrari\fR. 
The other group members are 
\fBAndres Albanese\fR, 
\fBAmit Gupta\fR, 
\fBWendy Heffner\fR,
\fBMark Moran\fR,
\fBColin Parris\fR, 
\fBClemens Szyperski\fR, 
\fBGiorgio Ventre\fR, 
\fBRon Widyono\fR,
and 
\fBMakiko Yoshida\fR. 
.sp .5
.LP
.B
Multicast real-time channels.\ \ 
.R
Scheme 1 is based on a simplex unicast abstraction. 
There are several important applications 
of integrated-services networks, 
e.g., 
all the applications involving multi-party collaboration, 
in which a more convenient 
(and potentially more efficient) 
abstraction is the simplex multicast connection. 
The group is investigating the issues involved in
replacing the unicast channel abstraction 
with the simplex multicast channel abstraction.
\fBAmit Gupta\fR and \fBMark Moran\fR have developed a scheme 
for handling the problem of delay 
and bandwidth allocation for multicasting in such broadcast media
as FDDI. 
The key problem consists 
of choosing among the different performance bounds assigned 
to the common nodes by the distributed partitioning 
and relaxation algorithm. 
\fBAmit Gupta\fR, 
\fBColin Parris\fR, 
\fBMark Moran\fR and \fBRon Widyono\fR are working 
on the multicast routing problem. 
They are designing a simulator 
for testing the different multicast routing schemes, 
including the traditional routing schemes 
discussed in literature as well as 
two new schemes that have been designed 
by members of the Tenet Group. 
.LP
.B
Advance reservation of real-time channels.\ \ 
.R
In the current Tenet scheme, 
the network provides the clients 
with Quality of Service guarantees during data transfer. 
However, 
for a service to be truly usable in multi-party applications,
the network ought to be able 
to guarantee the availability of its resources
at the time they will be needed.
This implies that the clients should be able 
to reserve 
channels with given characteristics and guarantees
in advance. 
\fBDomenico Ferrari\fR, 
\fBAmit Gupta\fR, 
and \fBGiorgio Ventre\fR
have designed mechanisms
for supporting advance reservations 
in real-time communication networks.
.sp .5
.LP
.B
Support for virtual real-time networks.\ \ 
.R
An interesting problem is that of
partitioning a network into several virtual networks, 
with performance guarantees for each virtual network.
This problem becomes more interesting, 
and important,
in real-time networking. 
Partitioning buffer space 
and bandwidth is fairly simple, 
but
partitioning the delay 
(or scheduler) resource 
is much harder. 
\fBDomenico Ferrari\fR and \fBAmit Gupta\fR
have designed an algorithm 
for partitioning all types of resources in each network node 
as the network managers desire.
.sp .5
.LP
.B
The channel group abstraction.\ \ 
.R
In the current Tenet scheme, 
the clients do not have any mechanism 
to specify any application-specific relationships 
that might exist among different channels. 
Consequently, 
the network may not make any assumptions 
about these relationships, 
and 
must consider each
channel as totally independent
of all others. 
\fBAmit Gupta\fR and \fBMark Moran\fR 
have proposed a new abstraction, 
called channel groups, 
for specifying such relationships.
The network uses the information 
about these relationships 
to provide a more efficient service to the clients. 
The channel groups also provide the network 
with a better client-service interface. 
Gupta and Moran are working on the various aspects 
of channel groups. 
The Galileo
simulator is being modified
to provide support for channel groups, 
and to investigate the usefulness
of the resource sharing relationship.
.sp .5
.LP
.B
The Berkeley Structured Channel (BSC) abstraction.\ \ 
.R
A BSC is an abstraction that tries 
to capture additional client requirements 
and needs in a structured way:\ \  
it represents a set of lower-level channels.  
As part of the task of defining the BSC levels,
\fBClemens Szyperski\fR is investigating ordering 
and synchronization requirements 
in multi-party multimedia conversations to see whether 
and how to map these to the  QoS parameters provided 
by a Tenet-style real-time communication service.
.sp .5
.LP
.B
Dynamic Channel Management algorithms.\ \ 
.R
In the Tenet model a connection-oriented and 
reservation-oriented approach is used 
to support guaranteed performance services. 
In this approach,
the resource allocation 
and route selection decisions are made before the start 
of the application on the basis of resource availability 
and real-time network load at that time, 
and are usually kept for the duration of the application. 
However, 
such an approach suffers from two major limitations:\ \  
first, 
the communication service provided is fixed, 
with no 
adaptability to dynamic changes in the clients' requirements; 
second, 
a lower utilization of the network 
by real-time traffic
may be obtained than would be possible
if the service were more flexible.
\fBColin Parris\fR, 
\fBGiorgio Ventre\fR, 
and \fBHui Zhang\fR 
have proposed a flexible management scheme 
that allows graceful adaptation 
of guaranteed performance service connections. 
Mechanisms have been devised, 
using the Dynamic Channel Management (DCM) algorithms, 
that allow modification of the traffic 
and performance parameters of a real-time connection 
during its lifetime. 
These mechanisms, 
together with an adaptation policy, 
can make more efficient use of the network resources 
by performing cooperative, 
consensual, 
high-level multiplexing.
In this policy, 
both the clients and the network can initiate 
an adaptation operation,
whereby the performance parameters 
of a client's connection are dynamically modified 
under the control of the client. 
The clients control this modification 
by specifying a range of values for each 
of the performance parameters 
at channel setup time
as well as 
a quantum by which the values of the parameters can be changed, 
and by providing their consent before each modification can be made. 
In client-initiated adaptation,
the clients dynamically request enhancements 
or reductions to the performance of their connections, 
while in network-initiated adaptation 
the network can elect to reclaim resources 
from the clients
(with their consent)
by reducing the performance levels
of their channels.
These reclaimed resources can be used 
to enable a new client to enter a heavily utilized network 
or a current client to increase the performance 
of its connection. 
Affected clients can be compensated 
by credits or other incentives. 
The goal of the adaptation policy is 
to increase the utilization of the network as much as possible 
by providing existing clients 
with the ability to enhance the performance level 
of their channels
(this enhancement may require reclaiming resources 
by network initiated adaptation) 
and new clients with network access
made possible
by reclaiming resources from existing clients. 
A simulator has been built, 
and simulation experiments have been performed 
to verify the correctness 
and usefulness of the policy.
.sp .5
.LP
.B
Fault recovery mechanisms.\ \ 
.R
\fBAnindo Banerjea\fR has modified a simulator written 
by \fBHui Zhang\fR and \fBColin Parris\fR, 
to study various schemes for introducing fault recovery
into real-time communication. 
Simulation experiments are in progress.
.NH 1 
Continuous-Media Networking Applications
.sp .5
.LP
.B
Multiparty interactive multimedia applications.\ \ 
.R
\fBClemens Szyperski\fR and \fBGiorgio Ventre\fR 
investigated the network requirements 
of multi-party interactive multimedia applications.  
A domain analysis starting with 
interpersonal communication patterns and 
extending to computer supported
applications led to a taxonomy 
of the associated interaction models.  
Based on this taxonomy,
the network support requirements 
for these applications were isolated. 
A specific observation was the importance 
of efficiently supporting conference or
classroom-style applications with a few key speakers 
and a potentially large audience that still wants 
to be able to interrupt the current speaker from time to time, 
e.g., to ask questions.  
A fully interconnected N to N communication structure would not
take advantage of the particular communication model of such applications.  
Better to explore these issues,
a half-duplex multicast model 
has been proposed and partially analyzed.  
The idea is a 1 to N communication structure, efficiently
implementable using a multicast tree,
that supports communication
from any of the N receivers 
(reversing direction of some of the tree edges), 
but under some restrictions on the number of concurrent senders 
(often only one or a few at a time) 
and on the QoS observed by receivers 
if someone else but one of the main sources is sending.  
A particular proposal for a transport-layer interface
based on the half-duplex multicast abstraction has also been made
to the Scheme 2 design group.
.sp .5
.LP
.B
Multimedia conferencing tools development and deployment.\ \ 
.R
\fBSteven McCanne\fR is currently coordinating 
multimedia application development and deployment.  
He integrated the IP multicast networking code 
into the Tenet 
version of the Ultrix
kernel, 
and ported two of the MBONE conferencing tools, 
vat and nv, 
to DECstations.  
(The MBONE is an IP Multicast virtual network built on top 
of the Internet.  
Vat is an audio conferencing application 
from Lawrence Berkeley Laboratory,
and nv is a network video tool from Xerox PARC.)
The nv port required the development 
of a new module to interface 
to DEC's TX/PIP video frame capture hardware.
He is also experimenting with the J-Video video compression hardware,
a new board under development by DEC.  
He has built a prototype multi-party video conferencing application, 
vic, 
which runs over UDP/IP multicast, 
UDP/IP unicast, 
and Tenet RMTP/RTIP.  
The low bandwidth requirements 
of a JPEG-encoded video stream allow real-time video conferencing 
to be carried out over current wide area networks 
(i.e., well under T1 speeds).
The motivation for the deployment 
of these network conferencing tools is twofold.  
First, 
they will provide a context for experimentation 
with real-time client requirements, 
as well as a live testbed for performance evaluation.
Second, 
they will provide a communications fabric for collaborative work.  
The experiments currently being carried out
on the MBONE indicate that network conferencing, 
even with today's "slow" networks, 
is extremely viable and productive.
This technology will soon be deployed in the
S2Knet and Xunet research communities.
McCanne also ported the GNU source-level debugger, 
with kernel debugging extensions from Lawrence Berkeley Laboratory, 
to the Tenet Ultrix kernel.  
Finally, 
he has taken part in the ongoing maintenance 
and development of the Tenet networking code.
.NH 1
Tenet Group Members
.PP
The current members of the Tenet Group are the following graduate students
of the Department of Electrical Engineering and Computer Science of
U. C. Berkeley: 
\fBAnindo Banerjea\fR,
\fBAmit Gupta\fR,
\fBWendy Heffner\fR,
\fBEdward Knightly\fR,
\fBSteven McCanne\fR,
\fBBruce Mah\fR,
\fBMark Moran\fR,
\fBColin Parris\fR,
\fBRon Widyono\fR,
and
\fBHui Zhang\fR;
the programmer
\fBTom Fisher\fR;
the following visiting scholars and researchers:
\fBWolfgang Effelsberg\fR, from the University of Mannheim, Germany;
\fBWinfried Dulz\fR, from the Institute for Computer Science (IMMD), 
University of Erlangen-Nuremberg, Germany;
\fBMasaya Miyazaki\fR, from the Information Systems Research Laboratory (ISL),
Matsushita Electric Industrial Co., Ltd., Osaka, Japan;
\fBWolfgang Schroeder-Preikschat\fR,
from the German National Research Center for Computer Science (GMD-FIRST),
Berlin, Germany;
\fBClemens Szyperski\fR,
from the Swiss Federal Institute of Technology (ETH), Zurich, Switzerland;
\fBFred Templin\fR,
from the External Research Program of Digital Equipment Corporation, Maynard,
Massachusetts, U.S.A.;
\fBGiorgio Ventre\fR,
from the Dipartimento di Informatica e Sistemistica of the Universit\o'a\(aa'
di Napoli, Naples, Italy;
\fBMakiko Yoshida\fR,
from the C&C Systems Research Laboratories, NEC Corp., Kawasaki, Japan;
the co-leader of ICSI's Networks Group,
\fBAndres Albanese\fR, 
and the leader of the Tenet Group,
\fBDomenico Ferrari\fR.
.NH 1
Tenet Group Publications
.PP
The Tenet Group publications since the
beginning of 1991 are listed below.
Unless otherwise noted, the publications
are available by electronic mail from the Tenet file server
\fB([email-masked])\fR.  
Instructions on how to use the file server 
may be obtained by sending it a mail 
message with the one-word subject: \fIHelp\fR. 
The same publications are also available by anonymous ftp to
tenet.berkeley.edu.
Inquiries for further information should be directed to the Tenet Group leader,
Professor \fBDomenico Ferrari\fR, Computer Science Division,
571 Evans Hall, University of California, Berkeley CA 94720.  
Electronic mail may be sent to \[email-masked]\fR.
.sp 1.5
.KS
.LP
A. Banerjea and S. Keshav,
\*QQueuing Delays in Rate Controlled Networks\*U,
Technical Report TR-92-015, 
International Computer Science Institute, Berkeley, February 1992;
also in
\fIProceedings of INFOCOM'93\fP, 
San Francisco, March-April 1993.
.KE
.KS
.LP
A. Banerjea and  B. Mah, 
\*QThe Real-Time Channel Administration Protocol\*U,
\fIProc. Second International Workshop on Network and
Operating System Support for Digital Audio and Video\fR, 
Springer-Verlag, Heidelberg,
Germany, pp. 160-170, November 1991.
.KE
.KS
.LP
R. C\o'a\(aa'ceres,
\*QEfficiency of ATM Networks in Transporting Wide-Area Data Traffic\*U,
Technical Report TR-91-043, 
International Computer Science Institute, Berkeley, July 1991.
.KE
.KS
.LP
R. C\o'a\(aa'ceres, 
\*QMultiplexing Traffic at the Entrance to Wide-Area Networks\*U, 
Ph.D. Dissertation, Technical Report UCB/CSD 92/717, 
University of California, Berkeley, December 1992.
.KE
.KS
.LP
R. C\o'a\(aa'ceres, D. P. Danzig, S. Jamin, and D. J. Mitzel,
\*QCharacteristics of Wide-Area TCP/IP Conversations\*U,
\fIProc. ACM SIGCOMM '91\fR, Zurich, Switzerland, 
pp. 101-112, September 1991.
.KE
.KS
.LP
P. Danzig, S. Jamin, R. C\o'a\(aa'ceres, D. Mitzel, and D. Estrin,
\*QAn Empirical Workload Model for Driving Wide-Area TCP/IP
Network Simulations\*U,
\fIJournal of Internetworking: Research and Experience\fR, 
vol. 3, no. 1, pp. 1-26, March 1992.
.KE
.KS
.LP
N. Faller,
\*QMeasuring the Latency Time of Real-Time UNIX-like Operating Systems\*U,
Technical Report TR-92-037, 
International Computer Science Institute, Berkeley,
June 1992.
.KE
.KS
.LP
D. Ferrari, 
\*QDesign and Applications of a Delay Jitter Control
Scheme for Packet-Switching Internetworks\*U, 
\fIProc. Second International Workshop on Network 
and Operating System Support for Digital Audio and Video\fR, 
Springer-Verlag, Heidelberg, Germany, pp. 72-83, November 1991;
also in \fIComputer Communications\fR, vol. 15, n. 6, 
pp. 367-373, July-August 1992.
.KE
.KS
.LP
D. Ferrari,
\*QDistributed Delay Jitter Control in Packet-Switching Internetworks\*U,
Technical Report TR-91-056, 
International Computer Science Institute, Berkeley,
October 1991; 
also in \fIJournal of Internetworking: Research
and Experience\fR, 
vol. 4, n. 1, pp. 1-20, 1993.
.KE
.KS
.LP
D. Ferrari, 
\*QReal-Time Communication in an Internetwork\*U,
\fIJournal of High Speed Networks\fR, vol. 1, n. 1, pp.79-103, 1992; also
Technical Report TR-92-001, International Computer Science Institute,
Berkeley, January 1992.
.KE
.KS
.LP
D. Ferrari, A. Banerjea, and H. Zhang,
\*QNetwork Support for Multimedia - A Discussion of the Tenet Approach\*U,
Technical Report TR-92-072, International Computer Science Institute, Berkeley,
October 1992.
.KE
.KS
.LP
D. Ferrari, A. Gupta, M. Moran, and B. Wolfinger,
\*QA Continuous Media Communication Service and its Implementation\*U,
\fIProc. GLOBECOM '92\fP, 8A.02.,
Orlando, Florida, December 1992.
.KE
.KS
.LP
D. Ferrari, J. Ramaekers, and G. Ventre,
\*QClient-Network Interactions in Quality of Service Communication
Environments\*U, \fIProc. 4th IFIP Conf. on High Performance Networking\fR,
pp. E1-1\(enE1-14, Liege, Belgium, December 1992.
.KE
.KS
.LP
T. Fisher,
\*QReal-Time Scheduling Support in ULTRIX-4.2 for Multimedia
Communication\*U,
\fIProc. Third International Workshop on Network and Operating System
Support for Digital Audio and Video\fR, San Diego, November 1992.
.KE
.KS
.LP
M. Gilge, 
\*QVisuelle Kommunikation ueber paketvermittelte Netze mittels 
netzwerkadaptiver Bildcodierung\*U, 4. Dortmunder Fernsehseminar, 
Dortmund, Germany, October 1991.
(not available from the file server)
.KE
.KS
.LP
M. Gilge and R. Gusella, 
\*QMotion Video Coding for Packet Switching Networks -- An Integrated 
Approach\*U, \fISPIE Visual Communications and Image Processing '91\fR, 
Boston, Massachusetts, November, 1991.
.KE
.KS
.LP
A. Gupta and M. Moran, 
\*QChannel Groups: A Unifying Abstraction for Specifying
Inter-Stream Relationships\*U, 
Technical Report TR-93-015, 
International Computer Science Institute, Berkeley, March 1993.
.KE
.KS
.LP
R. Gusella,
\*QCharacterizing the Variability of Arrival Processes with
Indices of Dispersion\*U, Technical Report TR-90-051, International
Computer Science Institute, Berkeley, September 1990; 
also in \fIIEEE Journal on Selected 
Areas in Communications\fR, vol. 9, n. 2, pp. 203-211, February 1991.
.KE
.KS
.LP
S. Keshav,
\*QCongestion Control in Computer Networks\*U,
Ph.D. Dissertation, University of California at Berkeley, September 1991;
also, Technical Report UCB/CSD 91/649, University of California,
Berkeley, September 1991.
(not available from the file server)
.KE
.KS
.LP
S. Keshav,
\*QOn the Efficient Implementation of Fair Queueing\*U,
\fIJournal of Internetworking: Research and Experience\fR, vol. 2, pp. 157-173, September 1991.
.KE
.KS
.LP
S. Keshav, 
\*QA Control-Theoretic Approach to Flow Control\*U,
Technical Report TR-91-015, International Computer Science Institute, 
Berkeley, March 1991; also in \fIProc. ACM SIGCOMM '91\fR, 
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E. Knightly and G. Ventre,
\*QGalileo: a Tool for Simulation and Analysis of Real-Time Networks\*U,
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C. Lowery,
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B. Mah, 
\*QA Mechanism for the Administration of Real-Time Channels\*U,
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M. Moran and R. Gusella, 
\*QSystem Support for Efficient Dynamically-Configurable 
Multi-Party Interactive Multimedia Applications\*U, 
\fIProc. Third International Workshop on Network and 
Operating Systems Support for Digital Audio and Video\fP, 
San Diego, November 1992.
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C. Parris and  D. Ferrari,
\*QA Resource Based Pricing Policy for Real-Time Channels in a Packet-Switching
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C. Parris, S. Keshav, and  D. Ferrari,
\*QA Framework for the Study of Pricing in Integrated Networks\*U,
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C. Parris, G. Ventre, and H. Zhang,
\*QGraceful Adaptation of Guaranteed Performance Service Connections\*U,
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C. Parris, H. Zhang, and D. Ferrari, 
\*QA Mechanism for Dynamic Re-Routing of Real-Time Channels\*U, 
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J. Ramaekers and G. Ventre, 
\*QQuality-of-Service Negotiation in a Real-Time Communication Network\*U, 
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J. Ramaekers and G. Ventre, 
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C. Szyperski and G. Ventre,
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C. Szyperski and G. Ventre,
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K. Umemura and A. Okazaki,
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D. Verma, 
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D. Verma and D. Ferrari,
\*QEvaluation of Overflow Probabilities in Resource Management\*U,
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D. Verma and D. Ferrari,
\*QVariation of Traffic Parameters in ATM Networks\*U,
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B. Wolfinger, 
\*QEin Transportdienst und -protokoll fuer Multimedia-Applikationen in 
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B. Wolfinger and M. Moran, 
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H. Zhang and D. Ferrari,
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H. Zhang and T. Fisher, 
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H. Zhang and S. Keshav, 
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