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Port Connections
100BASE-TX Ports
The Switch has eight Fast Ethernet 100BASE-TX
ports configured as MDIX (cross-over), which provide
a 100Mbps connection to other Fast Ethernet
devices such as the SuperStack II Switch 1000. The
maximum segment length is 100m (328ft) over cat-
egory 5 twisted pair cable.
As these ports are configured as MDIX (cross-over),
you need to use a cross-over cable to connect to
devices whose ports are MDIX-only. Most
100BASE-TX ports in 3Com devices are MDIX-only.
Plug-in Module
A slot at the rear of the unit can take a Plug-in
Module, providing an additional high-speed port if
required. This could be used to provide a Fast Ether-
net or Asynchronous Transfer Mode (ATM) backbone
connection to the rest of your network.
Switch Operation and Features
The Switch 3000 TX uses the same algorithm as a
conventional 802.1d bridge for filtering, forwarding
and learning packet addresses.
Intelligent Flow Management
Intelligent Flow Management (IFM) is a system for
controlling congestion on your network. Conges-
tion can be caused by one or more devices sending
traffic to an already busy port on the Switch. If a
port on the Switch is connected to another switch
or endstation, IFM prevents packet loss and inhibits
the device from generating more packets until the
period of congestion ends.
IFM should be enabled on a port if it is connected
to another switch, or an endstation. IFM should be
disabled on a port connected to a repeater.
For more information about enabling IFM, refer to
“
Setting Up the Switch Ports” on page 4-11.
Full Duplex
The Switch 3000 TX provides full duplex support
for all its fixed ports, and Fast Ethernet Plug-in
Module ports. Full duplex allows frames to be trans-
mitted and received simultaneously and, in effect,
doubles the potential throughput of a link. In addi-
tion, full duplex also supports 100BASE-FX cable
runs of up to 2km (6562ft).
Full Duplex can be enabled on all ports, or on indi-
vidual ports. For more information, refer to “
Setting
Up the Switch Unit” and “Setting Up the Switch
Ports” in Chapter 4.
Resilient Links
The Switch’s Resilient Link feature enables you to
protect critical links and prevent network downtime
should those links fail. Setting up resilience ensures
that should a main communication link fail, a
standby duplicate link immediately and automatically
takes over the task of the main link. Each main and
standby link pair is referred to as a resilient link pair.
For more information about resilient links, refer to
“
Setting Up Resilient Links” on page 4-18.