Glossary
6
Cisco 600 Series Installation and Operation Guide
78-11190-01
line rate
The speed by which data is transferred over a particular line type, expressed in
bits per second (bps).
logical port
A logical entry to a server machine. These ports are mostly invisible to the user,
though you might occasionally see a URL with a port number included in it.
These ports do not refer to physical locations; they are set up by server
administrators for network trafficking.
loopback
A diagnostic test that returns the transmitted signal back to the sending device
after it has passed through a network or across a particular link. The returned
signal can then be compared to the transmitted one. The discrepancy between the
two helps to trace the fault. When trying to locate a faulty piece of equipment,
loopbacks will be repeated, eliminating satisfactory machines until the problem
is found.
M
MAC
Media Access Control Layer. A sublayer of the Data Link Layer (Layer 2) of the
ISO OSI Model responsible for media control.
MIB
Management Information Base. A collection of objects that can be accessed via
a network management protocol, such as SNMP and CMIP (Common
Management Information Protocol).
modem pooling
The ability of a service provider to dynamically switch users’ messages between
modems, rather than requiring a modem to be dedicated to a particular user on a
network.
multiplexer
A device that can send several signals over a single line. The signals are then
separated by a similar device at the other end of the link. This can be done in a
variety of ways: time division multiplexing, frequency division multiplexing, and
statistical multiplexing. Multiplexers are also becoming increasingly efficient in
terms of data compression, error correction, transmission speed, and multi-drop
capabilities.
L
