4
Introduction
closet must be Category 5 certified. Where these blocks do not meet the
standard, an upgrade is necessary.
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 environment.
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 enterprise 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 coaxial
cables for horizontal wiring.
Network
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 maximum
10BASE-T Ethernet collision domain diameter can be up to 2500 meters.