Networking: A Beginner's Guide
Bus network topologies are by far the least expensive to install because they use
much less cable than the other two topologies and, accordingly, use less material and
need less installation labor.
But bus networks have some big drawbacks. Because all the subcables that make
up the segment and run from node to node must be connected at all times, and because
a failure in any part of the segment will cause the entire segment to fail, bus networks
are prone to trouble. And even more important, that trouble can take a long time to
track down, because you must work your way through all the cable connections until
you find the one causing the problem. Often, the source of the problem isn't visually
apparent, so you need to use various techniques and equipment to find it (as discussed
in the "Troubleshooting Coaxial Networks" section later in this chapter).
Because of the tendency of bus networks to be unreliable, new network wiring
installations do not use bus topologies, although many older networks still do.
Figure 4-2. BNC connectors used in a coax-based bus topology network
DEFINE-IT! BNC Connectors
Depending on whom you ask, BNC stands for Bayonet Nut Connector, British
Naval Connector, or Bayonet Neill-Concelman (with the latter two words standing
for its inventors, Mr. Paul Neill of Bell Labs and Carl Concelman of Amphenol
Corporation). BNC is a bayonet-style connector that quickly attaches and detaches
with a quarter turn. A variety of different parts--T-connectors, barrel connectors,
elbow connectors, cable ends that splice onto appropriate cable, and so forth--use
BNC connectors, so you can achieve nearly any type of connection needed. The
BNC connector is extremely easy to use and makes a secure connection.