The switches are connected by an optical patch cord. When transmitting data, errors increase on port 4912. Setting the speed and duplex on auto-negotiation or without auto-negotiation - the result is the same. The same cisco 2960S in conjunction with other models (3560G, 3750G - IOS) works correctly without errors. The problem is in CatOS?
These are the ports in 4912. Тhere are errors - cisco 2960, no errors - 3560