Specifications

Glossary
3
Cisco AS5800 Operations, Administration, Maintenance, and Provisioning Guide
DOC-7810814=
assigned numbers
RFC [STD2] documents the currently assigned values from several series of numbers used in network protocol
implementations. This RFC is updated periodically, and current information can be obtained from the IANA. If you are
developing a protocol or application that will require the use of a link, socket, port, protocol, and so forth, contact the IANA
to receive a number assignment.
async interface
Asychronous interface is used to terminate analog (async) dialin calls.
asynchronous transmission
This term describes digital signals that are transmitted without precise clocking. Such signals generally have different
frequencies and phase relationships. Asynchronous transmissions usually encapsulate individual characters in control bits
(called start and stop bits) that designate the beginning and end of each character. A method of sending data over a
communications line by placing a block of transmitted bits in an “envelope.” The envelope begins with a "start" bit that tells
a computer a character is beginning. The “stop” bit sends a message that a character has ended. Asynchronous transmission
also has the advantage of not needing precise clocking mechanisms that maintain a time relationship between transmitter and
receiver.
Asynchronous Transfer Mode (ATM)
An international packet switching standard. The standard uses a cell-switched approach, in which each packet of information
features a uniform size of 53 bytes (digital words of eight bits each). Of the total cell, 48 bytes is the “payload,” or information
to be transmitted. Five bytes are used as a “header,” providing all the addressing information for that particular packet. ATM
could switch and route information of all types, including video, voice and data.
authentication
In security, the verification of the identity of a person or process.
B
B channel
Bearer channel. In ISDN, a full-duplex, 64-kbps channel used to send user data. Compare to D channel, E channel, and
H channel.
backplane
Physical connection between an interface processor or card and the data buses and the power distribution buses inside a chassis.
bandwidth
Difference between the highest and lowest frequencies available for network signals. The term is also used to describe the rated
throughput capacity of a given network medium or protocol. The transmission capacity of a telecommunications link
(e.g., 64 kbps).
baseband
The total frequency band occupied by the aggregate of all the voice and data signals used to modulate a radio carrier.