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The university network shown in Exhibit 6 has the Nebula 2000 StarGazer network manager in place. This network management system provides a 3D graphics system that allows quick identification of network bottlenecks. A series of tools allows the network administrator to monitor network traffic in real time. Instantaneous feedback on individual ports and cumulative traffic allows the network manager to quickly identify network problems. A network topology feature allows the user to calculate and display the configuration of the current network topology. A trace port provides for the interface of a LAN analyzer that runs with a diagnostic program allowing the network manager to evaluate each active port without removing cables.

Various options allow the user to display the logical relationships of the Nebula switches and their relationship to other devices on the network. A port configurator function is available that allows the user to display the configuration of each Nebula port, its filtering setup, address resolution protocol leakage, and other control parameters in real time. The StarGazer is an icon-driven Windows product that provides a range of options for monitoring and gathering statistics.

For example, there are options for viewing the status of the Ethernet switch, set traffic thresholds, measure traffic at each of the ports, and measure and evaluate a range of network faults. There is also an option for simulating network segmentation and the impact of traffic on the segment in relation to Ethernet switching. This is a valuable aid in managing the placement of Ethernet switches across the network. StarGazer is an SNMP compliant network management system supporting both in-band and out-of-band SNMP management using Windows for ease of use.

ATM SWITCHING AND LAN EMULATION

Desktop ATM switching is being heralded as the next step in advancing the capability of a LAN or a multiple campus network to increase their throughput. This has become possible through the development of LAN emulation (e.g., LANE 1.0), an architecture developed by the ATM Forum that makes it possible for native LAN devices and protocols to communicate over ATM.

In recent tests using backbone ATM links, both IP and IPX Ethernet traffic could be handled easily over ATM. Although IP and IPX routing will work over Token Ring networks, source-ring bridging — a mandatory element in Token Ring networks — will not work over ATM. ATM integration can add significant complexity to a network configuration in terms of network management and network configuration.

Not Plug and Play

Although users have become accustomed to the shrink-wrap nature of the PC world, the connection-oriented nature of ATM, along with developing standards and new techniques, presents a steep learning curve for the network administrator. For example, each ATM session is a direct connection between devices that demand a different set of analysis procedures that are quite different from that of a shared LAN environment.

In addition, configuring an ATM gateway requires learning the operation of an entirely different device: an ATM switch. This dictates an additional set of tasks to get routers and servers properly interfaced. Such tasks involve configuring the ATM switch to establish the correct signaling protocol and related parameters.

ATM Is Not Cheap

ATM is still expensive because the equipment is still in limited production and the market is generally not ready to step up to the plate. For example, a baseline four-port ATM switch will cost about $33,000, while an ATM OC-3 port card for a router can cost as much as $26,000.

Aside from costs, the LAN administrator will have to plan carefully because ATM switches do not interoperate. For this reason, it may be wise to start first with point-to-point backbone arrangements before interlinking multiple servers.

Multi-Access LAN Servers

Service providers are emerging to support the transport of high-volume LAN traffic. For example, these companies provide multitenant access to a single high-speed communications link. The cost of these high-speed links can be charged back to multiple users at a fraction of what they might cost for a private network link. These transport services provide transport of IP and IPX traffic in an ATM pipe. They are supported by special ATM edge switches that are designed to completely fill an ATM pipe, making it economically feasible to support many different users at the same time.

An example of such a switch can be found in the NetEdge ATM Connect Switch, which is designed to support secure access to a single ATM link by multiple end users. This switch can support both permanent and switch virtual circuit arrangements. It will also support IP routing over SVC arrangements.

CONCLUSION

Newer high-performance workstations crowding the market are certain to expand the demand for bandwidth in the late 1990s and beyond. The introduction of low-cost Ethernet switches will allow network planners to extend the capabilities of their LANs as well as optimize degrading network performance as it may develop.

Switching technology provides the LAN administrator with the ability to preserve a growing network infrastructure investment while meeting the needs of the network user for more bandwidth. As the application of Asynchronous Transfer Mode begins to evolve, the network administrator positioned with Ethernet switches will be able to migrate into the higher-performance levels of ATM.


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