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Appendix D. Glossary

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

DLCI

data linkconnectionidentifier. A unique numberassigned to a PVC end pointin

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 terminalor computer thatplugsinto 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 codeviolations (CVs) are counted to determine

a current error rate. If this rate exceeds athreshold set bythe 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 aninter-

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).

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ADTRAN 1204006L1 Manual de usuario Pagina 184