58 GLOSSARY
loop An event that occurs when two network devices are connected by
more than one path, thereby causing packets to repeatedly cycle
around the network and not reach their destination.
MAC Media Access Control. A protocol specified by the IEEE for determining
which devices have access to a network at any one time.
MAC address Media Access Control address; also called hardware or physical address.
A layer 2 address associated with a particular network device. Most
devices that connect to a LAN have a MAC address assigned to them
as they are used to identify other devices in a network. MAC addresses
are 6 bytes long.
MDI Medium Dependent Interface. An Ethernet port connection where the
transmitter of one device is connected to the receiver of another
device.
MDI-X Medium Dependent Interface Cross-over. An Ethernet port connection
where the internal transmit and receive lines are crossed.
multicast A packet sent to a specific group of endstations on a network.
NIC Network Interface Card. A circuit board installed in an endstation that
allows it to be connected to a network.
POST Power On Self Test. An internal test that a Switch carries out when it is
powered-up.
protocol A set of rules for communication between devices on a network. The
rules dictate format, timing, sequencing and error control.
repeater A simple device that regenerates LAN traffic so that the transmission
distance of that signal can be extended. Repeaters are used to connect
two LANs of the same network type.
router A device that provides WAN links between geographically separate
networks.
RPS Redundant Power System. A device that provides a backup source of
power when connected to a Switch.
segment A section of a LAN that is connected to the rest of the network using a
switch or bridge.
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