Specifications

Page 32 DocSTAR Level 2 Service Training Workbook
Currently, ethernet hubs can communicate in two speeds 10Mbps and 100Mbps (Fast
Ethernet). You can purchase a 10Mbps hub, a 100Mbps hub, or a hub that can
communicate at either speed automatically.
What is a Switch and when should I use one instead of a Hub?
A Switch is a device much like a hub, which connects multiple computers to a central
point and regenerates the signal. However, a switch corrects traffic jam problems by
creating a ‘Virtual Circuit’, a direct path from the originating computer to the destination
computer(s) without transmitting signals to computers that were not intended to receive
the data. A switch remembers the address of every node on the network and anticipates
where data needs to go. The switch effectively eliminates unnecessary network traffic.
Based on the above information, it is easily seen that a switch would be very beneficial in
a network that was suffering network traffic jams because of data wandering the network
to find its destination. If there is high utilization on a hub it is probably a good candidate
for a switch.
What different types of network cabling & connectors are there?
The majority of networks today use three different types of cable:
? Coaxial
? Thin (thinnet)
? Thick (thicknet)
? Twisted-pair
? Unshielded twisted-pair (UTP)
? Shielded twisted-pair (STP)
? Fiber-optic
Coaxial cable
Coaxial cable has one conductor in the center surrounded by insulation, which is
surrounded by a wire mesh shielding to absorb electrical noise/interference surrounded by
an outer cover. Coaxial cable has two subsets: thinnet and thicknet. These describe not
only the physical appearance of the cable but also the effective transmission distances.
Thinnet- Carries signals up to approximately 185 meters (607 feet).
Thicknet- Carries signals up to approximately 500 meters (1640 feet).
The connector used for coaxial cable is the BNC connector. See Figure 3.5.
Figure 3.5 Coaxial cable design & BNC connector
Twisted-pair cable
Twisted-pair cable is actually one cable usually made up of four twisted wire pairs. There
are two types of twisted pair cable: shielded (STP) and unshielded (UTP). UTP is the