50 GLOSSARY
broadcast storm Multiple simultaneous broadcasts that typically absorb all the available
network bandwidth and can caus e a network to fail. Broadcast storms
can be due to faulty network devices.
collision A term used to describe tw o colliding packets in an Ethernet network.
Collisions are a part of normal Ethernet ope ration, but a sudden
prolonged increase in the number of collision s can indicate a problem
with a device, particularly if it is not accompanied by a general increase
in traffic.
CSMA/CD Carrier-sense Multiple Access with C ollision Detection. The protocol
defined in Ethernet and IEEE 802.3 standards in whi ch devices transmit
only after finding a data channel clear for a period of time. When two
devices transmit simultaneously, a collision occurs and the colliding
devices delay t heir retransmissions for a random length of time.
endstation A computer, printer or server that is connected to a network.
Ethernet A LAN specification developed jointly by Xerox, Intel and Digital
Equipment Corporation. Ethernet n etworks use CSMA/CD to transmit
packets at a rate of 10Mbps over a variety of cables.
Ethernet address See MAC addr ess.
Fast Ethernet An Ethernet system that is designed to operate at 100Mbps.
forwarding The process of sending a packet toward its destin ation using a
networking device.
filtering The process of screening a packet for certain characteristics, such as
source address, destination address, or protocol. Filtering is used to
determine whether traffic is to be forwarded, and can also prevent
unauthorized access to a network or network devices.
flow control A congestion con trol mechanism. Congestion is caused by devices
sending traffic to already overloaded port on a Switch. Flow control
prevents packet loss and inhibits devices from genera ting more traffic
until the period of congestion ends.
full duplex A system that allows packets to be transmitted and received at the
same time and, in effect, doubles the pot ential throughput of a link.
half duplex A system that allows packets to transmitted and received, but not at
the same time. Contrast with full duplex.
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