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The key element of this type of a strategy is the employment of network filtering to reduce the amount of traffic that flows across the network. This technique serves to contain extraneous traffic to the appropriate networks but allow passage of those packets of information with a specific requirement for access. Extensive application of MAC address filtering ensures that only those specific assigned users will have access to secured information resources. In this situation, the Nebula 2000 serves to selectively isolate traffic to specific LAN segments and broadcast groups to maintain overall performance levels.
Exhibit 6. San Diego Supercomputer Center.
This form of segmentation allows for parallel communications as well as the isolation of specific workstation groups with requirements for high-speed throughput. In addition, in a university or campus situation there is likely to develop a number of workgroups with a demand for large amounts of bandwidth. In the case of the University, many workgroups are engaged in special research projects where there is an unnatural distribution of high-speed workstations (e.g., Sun SPARC terminals, DEC, and UNIX-based servers). The design concept for this type of network architecture is to establish, at an early stage, the capability to isolate or reorganize high-speed workstations into communities of interest before they impact the performance of the network.
Exhibit 7. Existing Installation of Standalone Networks.
In a typical campus-type network environment, the application of a Nebula 2000 switch can greatly enhance the process for dividing the network into smaller more efficient workgroups. The Nebula 2000, supported by an established hierarchical structure across the campus, is capable of fully interconnecting each of the established subnetworks of the various departments. The Nebula 2000 filters the local traffic and connects specific segments at full wire speed. The university experiences frequent moves and changes, however, the Nebula 2000 StarGazer NM system can accommodate moves, additions, and changes to make for a very smooth implementation of a new LAN segment.
Exhibit 7 presents a general overview of a network for a large insurance company. Over the years their network expanded indiscriminately starting first as a Unisys minicomputer-based proprietary network. This network expanded to the point that the network was unable to support the user population. This gave rise to the establishment of several separate dedicated networks using PCs and high-speed workstations from Sun, Hewlett-Packard, and Digital Equipment Corp. There are now more than 350 workstations that comprise several functional LANs.
As the company expanded through acquisitions and customer growth, a number of disparate networks evolved. The application of LAN NOS (e.g., NetWare and Lantastic) allowed individual user groups to set up LANs by lines of business. This expedited the automation of the companys lines of business, but left the company with several customer database structures as well as a complex process for interLAN server communications.
Exhibit 8. Insurance Companies Networks (from Exhibit 7) with Interworking Components.
The establishment of a common corporate customer database greatly improves sales and customer service. Exhibit 8 shows one solution for a design concept for the insurance companys expanding network. This concept deploys intelligent hubs and a large-scale Bay Networks router to support an enterprisewide network. Because the insurance company has consolidated their operations in a high-rise office complex, their network can be organized based on a collapsed fiber backbone. The old proprietary network can now be phased out and a migration path established to phase out the old Unysis A-series platform.
Additional functional LANs can be phased in as required. For example, several functional LANs have been reestablished to support the fire and automobile lines of business on the casualty network. Health and life lines of business can now be supported to a newly established life policy network. The former administrative and Unysis network can now function to support E-mail, word processing, and general internal business applications (e.g., billing and receivables).
The integration of intelligent hubs incorporating Ethernet switches over a fiber backbone provides for the segregation of communities of interest onto separate subsegments. Additional Ethernet switches provide for the direct interconnection of selected servers to improve access to customer files. This arrangement makes it possible to contain the amount of enterprisewide traffic and keep like traffic within the same community of interest. Therefore, bandwidth can be kept to a minimum across the enterprisewide network.
Previously, server traffic often created network slowdowns during key periods of the work day because of frequent cross-server access by unrelated line-of-business users. To remedy this situation, some of the intelligent hubs have been introduced onto the network. This allows some of the key servers to be directly linked as well as some of their high-speed workstations. Once again, this strategy allows the network administrator to contain high bandwidth requirements to specific LAN subsegments optimizing the performance on the entire network.
The Bay Networks router functions as both a bridge and router, providing for multiprotocol routing of all network traffic. This arrangement provides a collapsed backbone network architecture over a fiber backbone media. This strategy supports the continued addition of functional LANs to support a variety of new lines of business.
When implementing hub-mounted Ethernet switching engines, it is necessary to maintain a complete view of the Ethernet switch elements in terms of topology, configuration, status, and performance. As can be seen in the university model in Exhibit 6 and the insurance company network in Exhibit 7, in a widely distributed network it would be possible to quickly lose track of their topology and the status of their switching configurations without a system for management. Although the switch vendors (e.g., Cabletron and Bay Networks) have network management systems available for their switch products, it is important to recognize the elements of management that are required to support a high-speed widespread LAN.
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