I have a client that is complaining about corrupted files whenever they send the files over their point 2 point T1 connection to the other office. I looked at the routers on both sides of the T1 (Cisco 2621XM routers) and noticed that in router A there are 17 CRC errors and 7 Frame errors since I reset the couters 6 hours ago. I believe this is why the clients files are corrupted. Can anyone tell me how I can further troubleshoot this. (Been a while since my cisco course) what can cause CRC and Frame errors on a ppp encapsulated point to point T1 connection between two Cisco routers.