Ethernet is ubiquitous in campus networks and Data Centers. Movement to consolidate networks has collapsed storage and virtualization, and telephony has put more traffic on Ethernet. Maintaining this critical infrastructure involves understanding the component pieces: Spanning Tree, VLANs, InterVLaN routing, and gateway redundancy.
Poor forwarding performance on switches is usually associated with cabling and port problems, duplex mismatch, or TCAM issues.
Problems at the physical layer can be seen from show interface, show interface counters and show interface counters errors. Look for the following errors:
Align-Err, runts: Alignment errors are usually associated with cabling, NICs, or duplex ...