| Term |
Definition
|
| CRC |
Cyclic Redundancy Check. This is a process that is used to check the integrity of a block of data. |
| FCS |
Frame Check Sequence. This field is used at the receiving end to determine if any transmission errors have occurred. |
| HDLC |
High-Level Data Link Control. This protocol corresponds to Layer 2, the Data Link Layer, of the ISO 7-layer architecture.
It is responsible for the error-free movement of data between network nodes. The HDLC layer ensures that the data
that is passed up to the next layer has been received exactly as transmitted. It also ensures that data is transmitted
only as fast as the receiver can receive it (flow control). The data is segregated into frames. |
| Q.921 |
An ITU-T recommendation, this is synonymous with LAPD. Q.921 contains address information and details the ISDN
frame format at the data link layer of the OSI/ISDN Model. It is also the ITU-T/OSI Layer 2 protocol used in the
D channel. |
|
X.25
|
An ITU-T recommendation, this standard is used with packet-switching networks. It defines the switched communications
service necessary when setup times are relatively fast. X.25 also details how data must be formatted in order to
cross the network. It defines how data streams are assembled into packets, controlled, routed and protected. |
