Answer:
Yes, error checking/correction is needed in layer 2.
Explanation: Bits are generally sent to the telephone in the physical layer without any error correcting scheme.
In layer 1, the presence of a central processing unit in each modem contains an error-correcting code.
The active error rate seen by layer 2 is highly reduced by layer 1.
Error correction is built in most modems nowadays. The active error seen in layer 2 is reduced with the aid of this built in error correction. Despite this, layer 2 errors are still possible.
There are still possibilities of errors in layer 2 even though the error checking/correction are done in layer 1.
Example: When a data is transferring from layer 1 to layer 2, unfortunately the data is lost due to lack of buffer space in layer 2. The error checking/correction mechanism will not be implemented in this situation. Therefore, the error will not be detected.
Thus, error checking/correction is needed in layer 2.
