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Dual-Speed Stackable Hubs User's Guide
Fast Ethernet is a relatively new standard specified by the IEEE 802.3 LAN
committee. It is an extension of the 10Mbps Ethernet standard with the
ability to transmit and receive data at 100Mbps, while maintaining the
CSMA/CD Ethernet protocol. Since Fast Ethernet is compatible with all
10Mbps Ethernet environments, it provides a straightforward upgrade with-
out wasting the company's existing investment in hardware, software, and
trained personnel.
Cables and Connectors
Category 5 unshielded twisted-pair (UTP) cables and shielded twisted-pair
(STP) cables are both supported. Category 5 UTP cable uses the same RJ-
45 connector used with 10BASE-T, wired in the same configuration.
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).
6
Introduction
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