R1#show controllers serial 0/0
HD unit 0, idb=0xD21B4, driver structure 0xD7640
Buffer size 1524 HD Unit 0,
RX ring with 16 entries at 0x622800
TX ring with 16 entries at 0x623000
An administrator cannot connect from R1 to R2. To troubleshoot this problem, the administrator has entered the command shown in the exhibit. Based on the output shown, what could be the problem?
The serial interface is configured for the wrong frame size.
The serial interface does not have a cable attached.
The serial interface has the wrong type of cable attached.
The serial interface has a full buffer.
The serial interface is configured for half duplex.