Filter
Top Products
Appendix D. Glossary
D-6 TSU IQ+ User Manual 61200275L1-1
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).