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Appendix A Glossary
Address mask
A bit mask used to select bits from an Internet address for subnet addressing. The mask is 32 bits long and
selects the network portion of the Internet address and one or more bits of the local portion. Sometimes called
subnet mask.
AAL5
ATM Adaptation Layer - This layer maps higher layer user data into ATM cells, making the data suitable for
transport through the ATM network.
ADSL
Asymmetric digital subscriber line.
ATM
Asynchronous Transfer Mode - A cell-based data transfer technique in which channel demand determines packet
allocation.
ATM offers fast packet technology, real time; demand led switching for efficient use of network resources.
AWG
American Wire Gauge - The measurement of thickness of a wire.
Bridge
A device connects two or more physical networks and forwards packets between them. Bridges can usually be
made to filter packets, that is, to forward only certain traffic. Related devices are: repeaters which simply forward
electrical signals from one cable to the other, and full-fledged routers which make routing decisions based on
several criteria.
Broadband
Characteristic of any network multiplexes independent network carriers onto a single cable. Broadband
technology allows several networks to coexist on one single cable; traffic from one network does not interfere with
traffic from another. Broadcast A packet delivery system where a copy of a given packet is given to all hosts
attached to the network. Example: Ethernet.
CO
Central Office. Refers to equipment located at a Telco or service provider's office.