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Glossary
clocking
Used in synchronous connections to provide a marker for the
start and end of data bytes. This is similar to the beat of a drum with a
speaker talking only when the drum is silent.
CLP
Cell Loss Priority: The area in the ATM cell header that determines
the likelihood of a cell being dropped during network congestion. Cells with
CLP = 0 are considered insured traffic and are not apt to be dropped. Cells
with CLP = 1 are considered best-effort traffic that may be dropped during
congested episodes, delivering more resources to handle insured traffic.
CLR
Cell Loss Ratio: The ratio of discarded cells to successfully delivered
cells in ATM. CLR can be designated a QoS parameter when establishing a
connection.
CO
Central Office: The local telephone company office where all loops in
a certain area connect and where circuit switching of subscriber lines occurs.
collapsed backbone
A nondistributed backbone where all network seg-
ments are connected to each other through an internetworking device. A col-
lapsed backbone can be a virtual network segment at work in a device such
as a router, hub, or switch.
collapsed core
A collapsed core is defined as one switch performing both
Core and Distribution layer functions. Typically found in a small network,
the functions of the Core and Distribution layers are still distinct.
collision
The effect of two nodes sending transmissions simultaneously in
Ethernet. When they meet on the physical media, the frames from each node
collide and are damaged. See also: collision domain.
collision domain
The network area in Ethernet over which frames that
have collided will spread. Collisions are propagated by hubs and repeaters,
but not by LAN switches, routers, or bridges. See also: collision.
composite metric
Used with routing protocols, such as IGRP and EIGRP,
that use more than one metric to find the best path to a remote network.
IGRP and EIGRP both use bandwidth and delay of the line by default. How-
ever, maximum transmission unit (MTU), load, and reliability of a link can
be used as well.
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