Introduction

Managing network switches often involves performing routine tasks such as identifying connected devices, checking VLAN assignments, configuring ports, and reviewing logs. Having a quick reference of commonly used switch commands can simplify day-to-day administration and troubleshooting.

Prerequisites

Before you begin, ensure you have:

  • Access to the network switch via SSH, Telnet, or console
  • Administrative or privileged (enable) access
  • Basic understanding of switch interfaces and VLANs

Implementation

Find the Switch Port Using a MAC Address

show mac address-table address xx:xx:xx:xx:xx:xx

Example output:

Aging time is 300 sec

Vlan    Mac Address         Port       Type
100     xx:xx:xx:xx:xx:xx  gi1/0/12   dynamic

View the MAC Address Connected to a Switch Port

show mac address-table interface gi1/0/2

Example output:

Aging time is 300 sec

Vlan    Mac Address         Port      Type
100     xx:xx:xx:xx:xx:xx  gi1/0/2    dynamic

Check the VLAN and Administrative Mode of a Port

show interfaces switchport gi1/0/12

Example output:

Administrative Mode: access
Access Mode VLAN: 100

Check the Speed and Status of a Switch Port

show interfaces status gi1/0/12

Example output:

Port      Type       Duplex  Speed  State
gi1/0/12  1G-Copper Full    100    Up

Change the VLAN of an Access Port

configure
interface gi1/0/<port_number>
switchport access vlan 100

Configure a Trunk Port

configure
interface gi1/0/<port_number>
switchport mode trunk
switchport trunk allowed vlan add <vlan_number1> <vlan_number2>
end

Shut Down a Switch Port

configure
interface gi1/0/<port_number>
shutdown

Save the Running Configuration

copy running-config startup-config

This saves the current running configuration so it persists after a reboot.

Create a New VLAN

configure
vlan database
vlan <vlan_number>

View All Ports Assigned to a VLAN

show vlan tag <vlan_number>

This displays all switch ports associated with the specified VLAN.

View Recent Switch Logs

show logging

This command displays the recent system logs, which can help during troubleshooting.

Conclusion

These commands cover many of the common tasks performed during network switch administration, including locating devices, checking interface status, configuring VLANs, managing switch ports, and reviewing logs. Keeping these commands handy can help speed up routine maintenance and troubleshooting activities.

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