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Introduction6
Topology
A Fast Ethernet workgroup is configured in a star topology and is built
around a maximum of two repeaters. Each workgroup forms a separate
LAN (also known as a segment or collision domain), and these workgroups
can be easily interconnected through switches, bridges, or routers to form
one LAN large enough to encompass a high-rise building or campus envi-
ronment. Recent innovations in LAN hub technology such as stackable
hubs, coupled with the decreasing cost of switches, bridges, and routers,
allow the design of low-cost, efficient Fast Ethernet workgroups and enter-
prise LANs.
The following factors strongly influence the architecture of Fast Ethernet
networks:
•
The EIA/TIA 568 Wiring Standard imposes a 100 meter limit on
horizontal runs of twisted-pair cables; that is, connections from the
wiring closet to the end-station.
•
Fast Ethernet’s increased operational speed reduces the maximum
distance between all elements of the LAN (see below).
•
The EIA/TIA 568 Wiring Standard does not support the use of co-
axial cables for horizontal wiring.
Network Diameter
Network diameter, which is the distance between two end-stations in the
same collision domain, is the primary difference between traditional
Ethernet and Fast Ethernet. Due to the increased speed in Fast Ethernet and
adherence to the EIA/TIA 568 wiring rules, the network diameter of a Fast
Ethernet collision domain is limited to 205 meters; in contrast, the maxi-
mum 10BASE-T Ethernet collision domain diameter can be up to 500
meters.