ADTRAN Cable T1 ESF CSU ACE User Manual page 61

T1 ESF CSU ACE
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.
encapsulation
A process by which an interface device places an end device's protocol-specific frames inside a frame rely
frame. The network accepts only frames formatted specifically for frame relay; therefore interface devices act-
ing as interfaces to a frame relay network must perform encapsulation. See also interface device or frame relay
capable interface device.
end device
The ultimate source or destination of data flowing through a frame relay network sometimes referred to as
DTE. As a source device, it sends data to an interface device for encapsulation in a frame relay frame. As a des-
tination 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.
FCS
frame check sequence. The standard 16-bit cyclic redundancy check used for HDLC and frame relay frames.
The FCS detects bit errors occurring in the bits of the frame between the opening flag and the FCS, and is only
effective in detecting errors in frames no larger than 4096 octets. See also CRC.
FDL
facility data link. A 4 bit/s non-disruptive management channel provided in ESF framing mode. This data link
conforms to ANSI T1.403 and AT&T TR 54016 specifications.
FECN
forward explicit congestion notification. A bit set by a frame relay network to notify an interface device (DTE)
that congestion avoidance procedures should be initiated by the receiving device. See also BECN.
file server
In the context of frame relay network supporting LAN-to-LAN communications, a device connecting a series
of workstations within a given LAN. The device performs error recover and flow control functions as well as
end-to-end acknowledgment of data during data transfer, thereby significantly reducing overhead within the
frame relay network.
frame-relay-capable interface device
A communications device that performs encapsulation. Frame-relay-capable routers and bridges are examples
of interface devices used to interface the customer's equipment to frame relay network. See also interface
device and encapsulation.
frame relay frame
A variable-length unit of data, in frame-relay format that is transmitted through a frame relay network as pure
data. Contrast with packet. See also Q.922A.
frame relay network
A telecommunications network based on frame relay technology. Data is multiplexed. Contrast with packet
switching network.
61204025L1-1B © 2004 ADTRAN, Inc
Appendix D. Glossary
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