Interphase iSPAN, Руководство пользователя

Страница: 216 / 236

196
Interphase Corporation
Asynchronous Transmission
◆
Method of sending data in which the
interval between characters may be of unequal length. The characters
transmitted include a start bit and one or more stop bits, which define
the beginning and ending of the character. No synchronizing or timing
signals need to be sent. Contrast with
Synchronous Transmission .
AT&T
®
5ESS
◆ The name of a central office switch manufactured by
AT&T. These switches use Custom (proprietary) or National ISDN-1
(NI-1) software. ESS stands for
Electronic Switching System .
Attenuation
◆ Signal power lost in a transmission medium as the sig-
nal travels from sender to receiver.
B8ZS (Bipolar with 8 Zeros Substitution)
◆
A method of digitally
encoding data on a link. A modified form of AMI used in USA.
Backward Explicit Congestion Notification (BECN)
◆ A bit set by a
frame relay network to notify an interface device (DTE) that conges-
tion avoidance procedures should be initiated by the sending device.
Bandwidth
◆ Capacity for transmitting data through a given circuit.
Generally, the greater the bandwidth, the more information can be sent
through a circuit during a given amount of time.
Basic Transmission Unit (BTU)
◆ In SNA, the unit of data and con-
trol information passed between control components. A BTU can con-
sist of one or more patch information units (PIUs).
Bc (Committed Burst Size)
◆ For Frame Relay , the maximum
amount of data in bits that a network agrees to transfer under normal
conditions over a measurement interval (T). Data may or may not be
contiguous. Bc is negotiated with the carrier provider.
B Channel
◆
A 56 Kbps or 64 Kbps bearer channel. Typically used
for delivering data or voice over ISDN.
Be
◆ See Excess Burst Size .
BECN
◆ See Backward Explicit Congestion Notification (BECN) .
Bearer Service
◆ A type of telecommunications service that provides
the capability to transmit a specific type of data such as voice or fax.
Bonding
◆
Bonding is the act of combining two 64Kbps B-channels
to derive a 128 Kbps channel. This is done by establishing two B-chan-
nel circuit switched calls and combining them in the customer's equip-
ment (using Multilink PPP or the bonding specification) or by
associating multiple B-channels in the network (multirate services).