Network Design
The Distributed Backbone
One method of creating a backbone network is to sequentially string all of the workgroup networks or hubs together. Cabling is run from one workgroup hub to the next, providing the necessary connections. This method of configuring a backbone network, as shown in Figure
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Figure 5-5. Distributed Backbone
A distributed backbone is usually the least expensive backbone network selection, as the only products required is the cabling that runs from one workgroup network to another. The problems inherent in the distributed backbone network are somewhat limiting, however:
•Connectivity Requirements - FDDI and Token Ring networks must form a complete, unbroken ring. Ethernet backbones are most effective if all workgroup networks are attached to a shared bus, such as a thick coaxial cable.
•Limited Expandability - While it is possible to simply add stations to a thick Ethernet backbone, the ring-dependent technologies (Token Ring and FDDI) require that existing cable be cut and terminated or replaced with additional cable runs when new workgroup networks are added to the backbone.
•Troubleshooting Complexity - If a distributed backbone suffers an error or a faulty cable, locating the fault in the network often takes up much of the total troubleshooting time. If a cable is at fault, the Network Manager may spend a lot of time pulling and testing new cabling.
•Limited Control - The use of a distributed backbone makes the isolation of workgroups from the rest of the overall network somewhat time-consuming. If a workgroup in a distributed backbone must be disconnected from the other networks physically, the distributed backbone requires that a Network Manager go out to the physical location of the workgroup network and disconnect the required cables, making any additions or changes necessary to keep the backbone network whole and operating.
The Workgroup in the Larger Network |
