A misconfiguration or a physical layer issue may cause the alignment error counter to increment.
Alignment errors are the count of the number of frames received that do not end with an even number of octets and have a bad Cyclic Redundancy Check (CRC). This could indicate a cable problem or a faulty transmitter on the network equipment connected at the other end. This count should be zero or very low. When the cable is first connected, some alignment errors may occur. Issue the show port command to check for alignment errors on a Catalyst OS (CatOS)-based switch. On a Cisco IOS -based switch, issue the show interface command to check for CRC errors.
To resolve alignment errors, perform these tasks:
Test the existing cable with a cable tester or replace it with a known good cable.
Hard set the speed and duplex settings if both sides of the link can be hard set.