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Cascading EIM Hubs Using Twisted-Pair Cabling
In shared Ethernet networks, repeating hubs and associated cabling all reside in a common collision domain. Expanding the network beyond the maximum allowable collision domain results in unstable operation. When expanding 10 Mbps twisted-pair networks, a maximum of four repeating hubs can be cascaded. Each  twisted-pair segment cannot exceed 100 m. No crossover cables are required since the EIM has an internal crossover port 4X. When port 4X is being used, port 4 must remain unused. In this example, the maximum network diameter is 500 m consisting of five 100 m twisted-pair segments and four repeating hubs.
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Cascading EI Hubs With One Fiber Optic Segment
The restriction that all repeating hubs and associated cabling must reside within the collision domain limits the deployment of fiber optics. However, it is possible to create a network of four repeating hubs and a mix of twisted-pair and fiber optic cabling. The end hubs incorporate twisted-pair cabling, on all ports, while the two inner hubs share a single fiber optic segment which can be up to 2 km in length.  All other twisted-pair segments are limited to 100 m in length. The EI Series does not have any internal crossover ports, so crossover cables are required for hub-to-hub connections. With fiber optics, it is just a matter of reversing one pair of connections. At 10 Mbps, ST fiber optic connectors are used. In this example, the maximum network diameter is 2400 m consisting of four 100 m twisted-pair segments, one 2 km fiber optic segment and four repeating hubs.
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Cascading EI Hubs with Two Fiber Optic Segments
A two-port fiber optic model is available in the EI series, which allows for the cascading of three repeating hubs using two fiber optic segments. In order not to violate the collision domain restriction, the two fiber optic segments cannot exceed an accumulative length of 2 km. The number of cascaded hubs in this configuration should not exceed the three that are shown. A one-port fiber optic repeating hub can be used at the two ends of the network to reduce cost.
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Cascading EISM Switches Using Twisted-Pair Cabling
 Switching hubs terminate one end of the collision domain; thereby, simplifying expansion rules. Switches can be cascaded theoretically without limit, as long as each twisted-pair segment is limited to 100 m. In the above example, no crossover cables are used since the EISM has an internal crossover port 5X. When port 5X is being used, port 5 cannot be used.
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