Layer 1

When troubleshooting Layer 1 issues, verify:

The installation of cables and connectors.
The behavior of LED status lights. For additional information about LEDs, see LEDs.
That the port is enabled, the link status is active, and speed and duplex parameters match the port settings at the other end of the cable.
1. To display the configuration of one or more ports, use the show ports configuration command.
That the packets are being received and transmitted.
1. To display the number of packets being received and transmitted, use the show ports {port_list | stack-ports stacking-port-list} statistics {no-refresh} command.
That there are no packet errors.
1. To display packet error statistics, use the following commands:
  
  show ports {port_list | stack-ports stacking-port-list} rxerrors {no-refresh}—Displays receive error statistics
  
  show ports {port_list | stack-ports stacking-port-list} txerrors {no-refresh}—Displays transmit error statistics
  
  show ports {mgmt | port_list |tag tag} collisions {no-refresh}—Displays collision statistics