User Manual

SPEEDLAN 9000 Series Installation and Operation User Guide Version 3.03
Glossary-3
Bit Error Rate
A measure of the number of errors in a digital transmission. Typically given as an exponential number that
represents the ratio of errors to total bits. Example: 1E-03 = 0.001 = 1.0 x 10-3 and 1.0E-6 = 0.000001
= 1.0 x 10-3. A single element in a binary code. A measure of the number of errors in a digital
transmission. Typically given as an exponential number that represents the ratio of errors to total bits.
Example: 1E-03 = 0.001 = 1.0 x 10-3 and 1.0E-6 = 0.000001 = 1.0 x 10-3.
Bridge
The function of a bridge is to connect separate networks together. This device operates at the DataLink Layer
of the OSI model. Bridges connect different network types (such as Fast Ethernet and Ethernet) or networks of
the same type. Bridges allow only necessary traffic to pass through the designated segments. When the
bridge receives a packet, the bridge determines the destination and source segments. If the segments are the
same, the packet is dropped, or filtered. If the segments are different, then the packet is “forwarded” to the
correct segment. Additionally, bridges do not forward bad or misaligned packets. Bridges are also called
“store-and-forward” devices because they look at the whole Ethernet packet before making filtering or
forwarding decisions. Filtering packets, and regenerating forwarded packets enables bridging technology to
split a network into separate collision domains.
Byte
A data unit consisting of eight bits.
Cable
A transmission medium of copper wire or optical fiber wrapped in a protective cover.
Channel
A specific band of frequencies designated for a specific purpose; the data path between two nodes.
Channel Service Unit/Data Service Unit (CSU/DSU)
Manages digital transmission and monitors signals for problems. Performs many functions similar to a
modem with the exception of converting digital signals to/from analog since the end device and transmission
facility are both digital.
Channel Spacing
The amount of space signals can flow through.