3Com 5000 Switch User Manual


 
2-8 DESIGNING AND EXPANDING THE NETWORK
Twisted Pair
Backbone, Twisted
Pair To-The-Desk
In constructing a twisted pair backbone, remember the following rule:
There can be no more than eight 24-Port modules in the path
between any two transceivers due to Ethernet's four-repeater rule.
This is because each 24-Port module counts as a 1/2 repeater unless
the signal goes in one port and out another port of the same
module, in which case the module counts as a full repeater.
You must add a bridge if you have more than eight 24-Port modules
serially connected. Each bridge creates a subnetwork. Each
subnetwork can have its own 4200 meter network diameter.
The configuration in Figure 2-2
illustrates a possible unshielded
twisted-pair network using 24-gauge cable.
Figure 2-2 Unshielded Twisted Pair Network
100 m
100 m
50 m
100 m
100 m
A
B
D
C