AT&T DEFINITY 555-230-223 - Manual (Page 23)

Installation
Task 4: Verify Components and
Connectivity
Study Figure 2-2 that follows to gain a general understanding of how the system
assembly is to be connected. Some customer-furnished LAN equipment is
included within the dotted lines in this figure. Helpful definitions for this
equipment are as follows.
Balun (balanced/unbalanced) — An impedance matching transformer.
Baluns are small, passive devices that convert the impedance of coaxial
cable so that its signal can run on twisted-pair wiring. They are used often
so that IBM 3270-type terminals, which traditionally require coaxial cable
connection to their host computer, can run off twisted-pair. Baluns work
for some types of protocols and not for others. There is often some
performance degradation with baluns, and the signal cannot run as far on
twisted wire as it can on coaxial cable.
10BaseT Hub — An Ethernet LAN that works on twisted pair wiring which
looks and feels like telephone cabling. 10BaseT Ethernet LANs work on
home runs in which the wire from each workstation snakes directly to the
10BaseT hub (like the wiring of a phone system). The advantages are
twofold — first, if one machine crashes, it doesn’t bring down the whole
network, and second, 10BaseT hubs often come with sophisicated
management software.
2-4 Issue 1 January 1996