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U.S. Robotics SureConnect ADSL Ethernet/USB Router User Guide
B
Bandwidth - Amount of data that can be transmitted over a given time period.
BPDU (Bridge Protocol Data Unit) - Data messages exchanged across switches in
an extended LAN with a spanning tree protocol topology. BPDU packets assure that
data arrives at the intended destination. These packets contain information on
addresses, costs, ports, and priorities. Network loop detection involves exchanging
BPDU messages across bridges. Loop deletion entails placing redundant switch ports
in a backup (blocked) state and shutting down selected bridge interfaces.
Bridge – A device that connects two LAN segments together. These LAN segments
may be of similar or dissimilar types, such as Ethernet and Token Ring. Inserting a
bridge into a network segments the network. The bridge improves performance by
keeping traffic contained within bridge segments.
Bridge Loop - Path that links one network segment to another. The spanning tree
protocol avoids bridge loops.
Bridge Priority - Determines which bridge becomes the root bridge.
Burst Size (Cells) - Maximum number of cells that the user can send at peak rate in
a burst. We measure burst size from within a sustainable rate.
C
CAP (Carrierless Amplitude and Phase Modulation) Modulation method used by
modems and DSL equipment. Based on QAM. Signals modulate two wideband
signals using passband modulation. CAP permits two to nine bits per frequency cycle.
Carrier wave - Periodic waveform. A carrier may be modulated or unmodulated. It
may also be continuous or switched. Typically, modems modulate the carrier wave
with a data signal. Modulation represents the data signal by impressing a variation on
some characteristic of the carrier wave. For instance, a circuit may represent the
signal as a proportional shift in carrier amplitude, frequency, or phase. Demodulation
(detection) eliminates the carrier wave and reproduces the signal. The carrier
frequency must be significantly greater than the signal frequency. A modem may
simultaneously apply more than one signal and more than one modulation method to
the same carrier. The modulation method may suppress the carrier before
transmission. In that case, the receiver must reinsert the carrier before demodulation
can occur.
CBR (Constant Bit Rate) - Service type that supports real-time applications with a
fixed bandwidth. These applications, such as a video stream, produce data at regular
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