| variable | 1 | 2 | 3 | 4 | 4 | 5 | 6 | 7 |
| ack_expected | 7 | 7 | 1 | 0 | 7 | 1 | 7 | 1 |
| next_frame_to_send | 2 | 2 | 2 | 2 | 2 | 2 | 3 | 2 |
| frame_expected | 5 | 5 | 5 | 0 | 5 | 5 | 5 | 5 |
| to_far | 1 | 1 | 1 | 4 | 1 | 1 | 1 | 1 |
| no_nak | ? | F | F | T | F | ? | ? | ? |
| nbuffered | 3 | 3 | 1 | 2 | 3 | 1 | 4 | 1 |
| arrived[0] | F | T | F | F | F | F | F | F |
| arrived[1] | F | F | F | F | F | F | F | F |
| arrived[2] | T | T | T | F | T | T | T | T |
| arrived[3] | T | T | T | F | T | T | T | T |
Problem 8: Resend frame 1
Problem 9: Send an ack for frame 4
Problem 10: If no_nak is true, send a nak frame, s, with s.ack = 4. In any case, no_nak is now false.