3Com 1000 - Manual (Page 26)

2-2 C HAPTER 2: I NSTALLATION AND S ETUP
Configuration Rules for Fast Ethernet
The topology rules for 100Mbps Fast Ethernet are
slightly different to those for 10Mbps Ethernet.
Figure 2-1 illustrates the key topology rules and pro-
vides examples of how they allow for large-scale
Fast Ethernet networks.
The key topology rules are:
■ Maximum UTP cable length is 100m (328ft) over
category 5 cable.
■ A 412m (1352ft) fiber run is allowed for connect-
ing switch to switch, or endstation to switch,
using half-duplex 100BASE-FX.
■ A total network span of 325m (1066ft) is allowed
in single-repeater topologies (one hub stack per
wiring closet with a fiber run to the collapsed
backbone). For example, a 225m (738ft) fiber
downlink from a repeater to a router or switch,
plus 100m (328ft) UTP run from a repeater out to
the endstations.
Configuration Rules with Full Duplex
The Switch provides full duplex support for all its
fixed Ethernet and Fast Ethernet ports, and Fast
Ethernet Plug-in Module ports. Full duplex allows
frames to be transmitted and received simulta-
neously and, in effect, doubles the potential
throughput of a link.
With full duplex, the Ethernet topology rules are the
same, but the Fast Ethernet rules are:
■ Maximum UTP cable length is 100m (328ft) over
category 5 cable
■ A 2km (6562ft) fiber run is allowed for connect-
ing switch-to-switch, or endstation-to-switch