ADTRAN TSU IQ+, 1204002L2 user manual Dlci

Appendix D. Glossary

DLCI

data link connection identifier. A unique number assigned to a PVC end point in a frame relay network. Identifies a particular PVC endpoint within a user's access channel in a frame relay network and has local significance only to that channel.

DSU

data service unit. A device designed to transmit and receive digital data on dig- ital transmission facilities.

DTE

data terminal equipment. The end-user terminal or computer that plugs into the termination point (DCE) of a communications circuit. The main difference between the DCE and the DTE is that pins two and three are reversed.

EER

excess error rate. The number of code violations (CVs) are counted to determine a current error rate. If this rate exceeds a threshold set by the user, the line is said to be in an excess error rate (EER) condition or state.

encapsulation

A process by which an interface device places an end device's protocol-specific frames inside a frame relay frame. The network accepts only frames formatted specifically for frame relay; therefore interface devices acting as interfaces to a frame relay network must perform encapsulation. See also interface device and frame-relay-capable interface device.

end device

The ultimate source or destination of data flowing through a frame relay net- work sometimes referred to as DTE. As a source device, it sends data to an inter- face device for encapsulation in a frame relay frame. As a destination device, it receives de-encapsulated data (i.e., the frame relay frame is stripped off, leaving only the user's data) from the interface device.

ESF

extended superframe. A framing format which consists of 192-bit frames grouped into 24-frame superframes where 12 of the 24 framing bits are used as an out-of-band communications channel. Of these twelve bits, six are used for frame synchronization and six are used for a cyclic redundancy check (CRC). This method greatly increases performance monitoring capability and enables remote performance monitoring not available in superframe (SF).

D-6 TSU IQ+ User Manual 61200275L1-1