ADTRAN 1204002L2, TSU IQ+ user manual Cir

Appendix D. Glossary

bridge

A device that supports LAN-to-LAN communications. Bridges may be equipped to provide frame relay support to the LAN devices they serve. A frame relay capable bridge encapsulates LAN frames in frame relay frames and feeds them to a frame relay switch for transmission across the network. A frame relay capable bridge also receives frame relay frames from the network, strips the frame relay frame off each LAN frame, and passes the LAN frame on to the end device. Bridges are generally used to connect LAN segments to other LAN segments or to a WAN. They route traffic on the level 2 LAN protocol (e.g., the Media Access Control address), which occupies the lower sub-layer of the LAN OSI data link layer. See also router.

bursty errored second See BES.

byte

Generally, an 8-bit quantity of information, used mainly in referring to parallel data transfer, semiconductor capacity, and data storage. Also, it is generally referred to in data communications as an octet or character.

carrier

The provider of the T1 service to the customer site. Carriers can be local tele- phone companies, regional telephone companies or any inter-exchange carrier such as AT&T, Sprint, or MCI.

CD

carrier detect. A signal generated by a modem or DSU/CSU. CD indicates the presence of a carrier signal on a communications link.

channel bank

Equipment in a telephone central office or customer premises that performs mul- tiplexing of lower speed digital channels into a higher speed composite channel. The channel bank also detects and transmits signalling information for each channel, thereby transmitting framing information so that time slots allocated to each channel can be identified by the receiver.

CIR

committed information rate. Less than or equal to the access rate, the CIR is used by the service provider for rate enforcement when the network is con- gested. When rates exceed the CIR, frames may be discarded.

61200275L1-1 TSU IQ+ User Manual D-3