DISTRIBUTED PROCESSING AND NETWORK ANALYSIS
ATM Network Stress Testing Based on the TelePath paradigm
McClellan.
Center for Telecommunications Research (CTER), University
of Alabama at Birmingham (UAB).
In the conventional practice of surgical pathology, a highly trained
specialist uses light microscopy to diagnose portions of tissue removed
during surgery. Researchers at UAB have prototyped and validated an interactive
telepathology system using a robotic microscope and digital imaging system
for interactive delivery of diagnostic-quality microscopic images to a
remote specialist. The TelePath system provides a remotely located
pathologist with real-time, user-friendly control of the robotic microscope,
and creates a "virtual network microscope" accessible by a variety
of Internet-capable computers. When used in the surgical environment for
intra-operative consultation, the "virtual network microscope"
concept mandates a level of network performance that will allow the completion
of a remote diagnosis in about 15 minutes. The uncompressed data volume
that must be transmitted in this case ranges from 10 megabytes (MB) to
over 100 MB during the diagnostic interval (including the pathologist review
time). Due to unique requirements for speed, accessibility, reliability,
and bandwidth, this application is incompatible with existing multiple-access,
non-prioritized network paradigms.
The TelePath system also presents a unique process requiring
multiple, simultaneous QoS guarantees from the network, since the usual
intra-operative scenario involves a patient under anesthesia and a surgical
team waiting for a time-critical diagnosis from a remote pathologist. During
routine use, the TelePath application records all network activity
generated by the remote pathologist. This information, colloquially dubbed
the "trajectory of the diagnosis", can be replayed in a Monte
Carlo simulation where a "simulated" pathologist re-issues exactly
the same sequence of commands into a network configuration with specified
service, reliability, traffic, or connection characteristics. The TelePath
system trajectories and the tools of statistical inference will be used
to test and verify several inter-network enhancements, particularly those
related to resource reservation over IP (RSVP, RFC 1633) and the mapping
of these methods to those of ATM Quality of Service parameters (QoS). The
TelePath system is well suited to this evaluation strategy since
it provides the context of an actual, clinically verified medical application
and uses actual diagnostic data from practicing pathologists. Considerations
addressed in this automated validation environment include repetitive testing
of multiple network architectures; strategies for adequately, predictably,
and cost-effectively handling IP-over-ATM traffic; and optimization of
QoS specifications and billing strategies for a specific class of validated,
marketable IP-over-ATM traffic (i.e. the TelePath application).
Center for
Telecommunications Education and Research - the TelePath Tele-Medicine
Project.
(see a Microsoft
PowerPoint
Presentation)
Mobile Network Applications Test-bed
University of Alabama (Tuscaloosa).
The University of Alabama and Georgia Institute of Technology are collaborating
on mobility problems associated with the Internet. Each university is separately
developing an environment where mobility (non-wireless and wireless) is
possible. While this work is not unique in that many universities have
networks that allow local mobile computing and networking, our focus is
on wide area mobile computing and networking.
There are many open problems in attaining mobility across the Internet.
In October 1996, the IETF adopted a standard for location management in
IPv4. Currently, the Mobile Working Group of the IETF is developing Internet
drafts for extensions to Mobile IPv4 and for Mobile IPv6. Since these standards
are not finalized, different products for mobility are being developed
by different organizations; all of these products are installed for local
area mobility only. While mobile applications can be developed in a local
area, it is difficult to evaluate how alternative design approaches will
function in a wide area.
Mobility burdens applications in ways that are unique to this environment.
Consider, for example, interruption in connectivity and delay characteristics.
Wide area mobility features can be approximately simulated in our local
area networks, but having a real wide area test-bed is obviously preferable.
The infrastructure for wide area mobile computing and networking is, however,
not in place. Therefore, we propose to install a sparse virtual LAN (VLAN)
on top of vBNS across our two campuses. Since routing to mobile hosts is
not an issue with a VLAN (i.e., packets are broadcast to all hosts on the
VLAN at the ATM level), this VLAN can supply a test-bed for wide area mobility
and aid in the development of mobile applications. Although scalability
is a problem in this implementation of wide area mobility, a few other
universities should be able to join this wide area mobile application test-bed
without performance degradation. Furthermore, if the interest in a wide
area mobility test-bed is high, other scalable options for implementation
of the test-bed will be considered. For example, the router of a GRF 16x16
crossbar switch could be modified to build a wide area mobility test-bed
on top of Internet2. A connection to the vBNS will enable exploration of
wide area mobility implementations without the restrictions of IPv4 (e.g.
triangle routing).
There are many alternative approaches to mobile applications that can
be considered once this wide area test-bed is established. For wireless
applications, both universities are in the process of installing WAVELAN.
The existence of a high bandwidth connection between the University of
Alabama and Georgia Institute of Technology will allow effective testing
of future high bandwidth mobile applications.
Distributed Parallel Processing in "tuple-space"
Hyatt.
Computer & Information Science, University of Alabama at Birmingham
(UAB).
A distributed processing system called "tuple-space", loosely
modeled on the Linda distributed programming system developed at Yale,
allows design of parallel programs that can be distributed over a heterogeneous
mix of machines connected by a reasonably fast network (unshared 10Mb/s
ethernet works reasonably well). Test algorithms developed include a distributed
GPSS-like simulation language, a distributed game-tree search, a distributed
database system, and other projects where performance was a major concern.
The "tuple-space" system will be used to distribute an application
so that processes run locally on machines at UAB, remotely on a supercomputer
at a national supercomputer center, and remotely on computers at collaborating
sites. To make this viable, reasonable bandwidth and latency guarantees
must be available since delays in communication between distributed processes
cause adverse effects on parallel execution performance.
Simulations of Action Potential Propagation in Models
of Cardiac Tissue
Pollard, Rogers.
Biomedical Engineering (BME), University of Alabama at Birmingham
(UAB).
The heart is made up of crossed fibers connected to one another
to form an intricate web of tissue. The complex nature of this web makes
the heart a three-dimensional anisotropic media. As a result, many results
from conventional one- and two-dimensional simulations of action-potential-propagation
are not directly applicable to cardiac function. To achieve routine solutions
of these problems three-dimensional grids, parallelized and vectorized
simulations have been developed by BME researchers to be compatible with
existing supercomputer architectures. The ability to integrate remote supercomputer
facilities into local simulations for real-time visualization in parallel
with results from local calculations will make the three-dimensional simulation
of cardiac stimulus practical.
Large Scale Simulations of Materials/Molecular Physics
Simultaneous Equations Using Massively Parallel Computers
Kawai .
Department of Physics, University of Alabama at Birmingham (UAB).
Programs developed at UAB to simulate dynamics of atoms from first principles
are called parallel ab initio molecular dynamics (PAIMD). The PAIMD
simulator simultaneously solves many electron Schrodinger equations and
atomic motion equations, and requires up to 10 GB of memory, generating
output files up to 1 GB. Analysis of such large data sets requires large
scale, animated visualizations. Because of the current slow, non-deterministic
Internet traffic, data from several successful simulations (many 100 GB
in size) must be left in national supercomputer centers without detailed
analysis. High-speed, deterministic access to national supercomputer centers
will facilitate transfer of this data to a local graphics workstation where
a more advanced visual analysis can be performed off-line or in real-time
as the simulations evolve.
http://www.phy.uab.edu/~kawai
http://solid2.phy.uab.edu/
Contaminant Flow in Aquifers Modelled Using Partial Differential Equations
Knowles, Zeng, Department of Mathematics, University of Alabama at Birmingham
(UAB).
Currently, two dimensional models of groundwater systems are being developed. The next stage will
consider the three-dimensional modelling of contaminant flow in aquifers. Calculations for this project will require use of
the Alabama State Supercomputer Center in Huntsville, with real-time transmission of graphics illustrating the
calculations as they are performed. The project also involves collaboration with a group at StonyBrook and use of
a 128 node Paragon supercomputer at that location with remote visualizations in real-time.
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