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7.1 | |
10-Mbps and 100-Mbps Ethernet | |
| 7.1.5 | |
10BASE-T wiring and architecture |
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10BASE-T links generally consist of a
connection between the station and a hub or switch. Hubs are
multi-port repeaters and count toward the limit on repeaters between
distant stations. Hubs do not divide network segments into separate
collision domains. Because hubs or repeaters merely extend the length
of a network segment within a single collision domain, there is a
limit on how many hubs may be used in that segment. Bridges and
switches divide a segment into separate collision domains, only
leaving the media limitations to determine the distance between the
switches. 10BASE-T limits the distance between switches to 100 m (328
ft). Although hubs may be linked, it is best to avoid this arrangement. This is to prevent exceeding the limit for maximum delay between distant stations. When multiple hubs are required, it is best to arrange them in hierarchical order as to create a tree structure. Performance will be improved if fewer repeaters separate stations. An architectural example is shown in
Figure 10BASE-T links can have unrepeated distances up to 100 m. While this may seem like a long distance, it is typically “used up” when wiring an actual building. Hubs can solve the distance issue but will allow collisions to propagate. The widespread introduction of switches has made the distance limitation less important. As long as workstations are located within 100 m of a switch, the 100 m distance starts over at the switch.
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All distances between stations are acceptable. However, the total
distance from one end of the network to the other, places the
architecture at its limit. The most important aspect to
consider is how to keep the delay between distant stations to a
minimum, regardless of the architecture and media types involved. A
shorter maximum delay will provide better overall performance.
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