Glossary
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compression
A technique to send more data across a link than would be
normally permitted by representing repetitious strings of data with a single
marker.
configuration register
A 16-bit configurable value stored in hardware or
software that determines how Cisco routers function during initialization. In
hardware, the bit position is set using a jumper. In software, it is set by spec-
ifying specific bit patterns used to set startup options, configured using a
hexadecimal value with configuration commands.
congestion
Traffic that exceeds the network's ability to handle it.
congestion avoidance
To minimize delays, the method an ATM network
uses to control traffic entering the system. Lower-priority traffic is discarded
at the edge of the network when indicators signal it cannot be delivered, thus
using resources efficiently.
congestion collapse
The situation that results from the retransmission of
packets in ATM networks where little or no traffic successfully arrives at
destination points. It usually happens in networks made of switches with
ineffective or inadequate buffering capabilities combined with poor packet
discard or ABR congestion feedback mechanisms.
connection ID
Identifications given to each Telnet session into a router.
The show sessions command will give you the connections a local router
will have to a remote router. The show users command will show the con-
nection IDs of users telnetted into your local router.
connectionless
Data transfer that occurs without the creating of a virtual
circuit. No overhead, best-effort delivery, not reliable. Contrast with: con-
nection-oriented. See also: virtual circuit.
connection-oriented
Data transfer method that sets up a virtual circuit
before any data is transferred. Uses acknowledgments and flow control for
reliable data transfer. Contrast with: connectionless. See also: virtual circuit.
console port
Typically an RJ-45 port on a Cisco router and switch that
allows command line interface capability.
contention media
Media access method that is a baseband media; that is,
first come, first served. Ethernet is an example of a contention media access.
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