Fluke 2680A User Manual page 251

the computers and other devices attached to the network wiring. The Ethernet
standard consists of a set of low-level addressing and data transmission protocols
that run on several different wiring schemes.
Computers on a network are usually referred to as a "host." The 2680 Series
instruments are hosts in this context. Instruments that facilitate communication
between different sections of a network are called by names that indicate their
function, for example, routers, bridges, repeaters, etc.
Physical Layer Wiring Schemes Supported by 2680 Series
The 2680 Series supports the most common wiring scheme used in Ethernet
networks: 10/100BaseT (or UTP).
The 10/100BaseT wiring method uses two or four pairs of twisted wires. It is also
referred to as Unshielded Twisted Pair (UTP) wiring. This wiring method supports
only two connections to any one run of wire. To support more than two
connections, an active instrument called a "hub" must be used.
A hub is an active device that supports multiple 10/100BaseT connections. The
network host attached to each connection of the hub may communicate with every
other host attached to the hub. Hubs also may allow other types of cable
connections, such as 10Base2 and 10Base5 (fat coax). This is done to allow a hub
to communicate with other network hosts, such as other hubs, routers, and bridges.
A hub is sometimes referred to as a network switch.
If you want to use 10/100BaseT wiring without a hub (to connect one 2680 Series
instrument and one PC), you must use a special 10/100BaseT cable. This is
necessary because both hosts transmit and receive on the same pair of wires within
the cable. To operate correctly in a direct wiring situation, these pairs must be
crossed in the cable, so that the transmitter on one end is connected to the receiver
on the other.
The 10/100BaseT wiring method is very popular because the wire is inexpensive
to purchase and install, the use of a hub allows some protection from
malfunctioning network hosts, and this type of wiring is easier for network
administrators to manage and control.
Network Interconnection Devices
The following basic devices are used in networks to extend, partition, and
interconnect networks:
•
A repeater is a device used to physically isolate and extend the length of a
network segment, but it does not divide the network into subnets.
•
A hub is a device that allows communication among multiple 10/100BaseT
network hosts and allows these hosts to communicate with other Ethernet
wiring. Some hubs also perform Router functions.
Appendices
Network Considerations
H
H-3