User's Manual

Table Of Contents
SPEEDLAN 8500 Series Installation and Operation User Guide
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 ele-
ment 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.
IDU
The function of a IDU is to connect separate networks together. This device operates at the DataLink Layer of the OSI
model. IDUs connect different network types (such as Fast Ethernet and Ethernet) or networks of the same type. IDUs allow
only necessary traffic to pass through the designated segments. When the IDU receives a packet, the IDU determines the
destination and source segments. If the segments are the same, the packet is dropped, or filtered. If the segments are dif-
ferent, then the packet is “forwarded” to the correct segment. Additionally, IDUs do not forward bad or misaligned pack-
ets. IDUs 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.
IDU
This device is a combination of a router and a IDU in one product.
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.