Troubleshooting the Switch

Beyond configuration, accessing the switch’s console port or connecting across the network, gives us both diagnostic and troubleshooting abilities. Depending on the nature of the problem, some of the following troubleshooting tasks may help when working with switches.

First, determine switch communication via ping, a Telnet session, a web browser, or an SNMP system. When there’s no communication with a switch, the only communication possible is via the console port.

Most switch vendors offer a way to check the following:

  • Port statistics: View port error and traffic statistics for abnormalities
  • Port configuration: Verify speed and full-duplex operation.
  • Port security: Check to see if the port is locked down to a particular MAC address.
  • LEDs on the switch: Most vendors use LEDs for the ports on the switch. If it appears that they are continually flashing, a broadcast storm may be occurring.
  • Lookup tables: View the MAC address entries in the lookup table.
  • Port mirroring: Configure a port to connect an analyzer for viewing traffic going through the switch.

Related Courses
Understanding Networking Fundamentals
SWITCH — Implementing Cisco IP Switched Networks v1.0
Wireless LAN Foundations

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