Expo/Computation/The Metacomputer

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Networks

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Networks are critical to the success of the metacomputer. They must transmit data from one computer to another at very high speeds--gigabits or billions of bits every second. If you've got data pouring from a supercomputer like water from a firehose, you don't want to transmit that data to another computer with a garden hose.

Moreover, the networks must transmit all that data reliably, possibly over large distances. Networks bring the power of computers--wherever they may be--to the scientist in the laboratory, the librarian in the library, the physician in the hospital, the student in school. Increasingly, networks must be able to transmit audio and visual information as well as data, and also support interactive applications, including virtual reality.

NCSA uses a number of networking technologies, both local and far-reaching, in support the metacomputing.

Local Area Networks
Wide Area Networks
Networking Testbeds


Local Area Networks:

Local Area Networks (LANs) typically connect an in-house collection of desktop workstations to each other and possibly to a central computer.

From Ethernet to HiPPI

Many LANs employ Ethernet, which connects computers at up to 10 megabits or millions of bits per second. NCSA uses Ethernet to link all of its lower performance workstations and personal computers. Ethernet is fine for many kinds of work on a LAN, but when researchers begin to retrieve or send send large numbers of large files over the network, they must turn to faster networking technologies.

The current network "backbone" of NCSA's LAN is provided by a Fiber Distributed Data Interface (FDDI), which uses fiber-optic cable to provide connections, at up to 100 megabits per second, between NCSA's high-end supercomputers and a number of high-speed workstations.

A High Performance Parallel Interface (HiPPI) network provides even faster (800 megabits per second) connections between supercomputers, or between supercomputers and high-end workstations. HiPPI's copper cables are limited to 25 meters in length, so it's generally used to connect high-performance computers in the same building.

Advanced Computation Building

These length limitations notwithstanding, NCSA recently expanded the HiPPI network beyond its Advanced Computer Building into two other buildings: its facilities in the Beckman Institute, which house the Numerical Laboratory and the CAVE; and to the nearby Digital Computer Laboratory.
Beckman Institute Digital Computer Laboratory

Stepping up to ATM

The world of high-performance computing is constantly changing, and networking technologies are no exception. NCSA is working toward replacing their current technologies with an emerging standard for telecommunications networks, called ATM (much as we'd all like to get cash over the network, ATM stands for Asynchronous Transfer Mode, not Automated Teller Machine).

ATM Networks
ATM networks, which function anywhere from 1.5 megabits per second all the way up to 9.6 gigabits (billions of bits) per second, carry voice, data and video over a single line. But ATM offers more than just potential speed. Past efforts to integrate local and wide area newtorks have been plagued by differences in network architectures and protocols (the set of conventions between communication lines and links to the messages to be exchanged). Incorporation of ATM technology into wide area networks will help eliminate the seams between LANs and WANs.
JPEG Image (44.8 KB); Credits and Copyrights

Wide Area Networks

NSF Net Backbone

Wide Area Networks (WANs) connect computers across cities, region, countries, even continents. NCSA's local area network, for example, is connected to the Internet at a "node" in Chicago; the San Diego Supercomputing Center mostly uses a San Francisco node. The nodes in turn are connected to each other, and it's through the nodes that all Internet traffic must pass.
JPEG Image (35.6 KB); Credits and Copyrights

NSF Network

Originally a federally funded network connecting a relatively limited number of researchers, the Internet now connects tens of thousands of academic, commercial and government sites both here and abroad.
JPEG Image (40.1 KB); Picture Caption and Credit

In the U.S., the Internet is fast becoming self-supporting via commercial interests. While the capacity of the Internet backbone (45 megabits per second) is adequate for most applications, it's too slow for the most demanding applications where data rates may approach a Gigabit per second.

Networking Testbeds

In order to handle the most challenging applications of metacomputing, the Federal Government's HPCC Program supports a number of high-speed network testbeds.

Very-High Bandwidth Network Service (vBNS)

This ATM-based network connects all five NSF supercomputing centers and several other research institutions at speeds of 155 megabits per second. At these speeds, most applications will run nearly as quickly as though all the machines were in the same room.
JPEG Image (65.9 KB); Credits and Copyrights

vBNS is a major artery in another networking experiment called the I-WAY (Information Wide Area Year), a network that links dozens of the nation's fastest computers and advanced visualization environments.

Information Wide Area Year network (I-WAY)


Supercomputing '95/I-Way

The virtual environments, data sets, and computers reside at sites connected by 11 networks employing varying bandwidths, protocols, and routing and switching technologies.

Full Map

The I-WAY is the first truly national scale high-performance ATM applications-driven testbed. Some of the first users of the I-WAY will demonstrate the network at Supercomputing '95.

JPEG Image (27.7 KB); Credits and Copyrights

Virtual Environments Application Map

This application map shows how a distributed virtual reality application involving CAVE and Immersadesk environments employed the vBNS as part of the I-WAY in demonstrations at Supercomputing '95 and in subsequent experiments.
JPEG Image (28.4 KB); Credits and Copyrights

Experimental Universities Network (XUNET)

The XUNET (Experimental Universities Network) Communications Program, supported by AT&T Bell Laboratories and the NSF, is a 45 megabit/second network that spans the continent: from The University of California-Berkeley (UCB) and the Lawrence Berkeley Laboratory (LBL) in California, to the University of Illinois and the University of Wisconsin-Madison in the midwest, to Bell Labs in New Jersey.

Linked to XUNET was the BLANCA testbed, only recently completed. The BLANCA testbed ran between the University of Illinois and the University of Wisconsin-Madison, and between UCB and LBL, at 622 megabits/second--fast enough for collaborating space scientists to observe data from earth-orbiting satellites and change the paths of the satellites in real time.

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Copyright, (c) 1995: Board of Trustees, University of Illinois


NCSA. Last modified 11/4/95.