This is a short post with a few useful commands for configuring and troubleshooting Cisco switches.
To show the current configuration:
show running-config
Show the switches firmware version and model:
show version
Show serial numbers:
show inventory
To save the current configuration:
copy running-config startup-config
Reboot switch:
Reload
Show details about the current interface, the below shows you information about port 49 on this switch:
show interface Ethernet1/49/1
If your switch port is in a port-channel you will need to show the details for the port-channel interface:
show interface port-channel 21
When troubleshooting it may be necessary to see the MAC addresses of the devices that are connected to the switch port. To do this run the below, it will show you the MAC addresses of all the devices connected to port 49:
show mac address-table interface Ethernet1/49/1
Show the MAC address details for a specific MAC address you are looking for:
show mac address-table address 0016.bad8.3fbd
Show all the MAC address entries for VLAN 10:
show mac address-table vlan 10
These commands will enable configuration mode, select interface eth1/27, enable terminal monitoring (so we can see the status of the port) and disable the port:
configure terminal int eth1/27 do term mon shut
These commands will do the same as above but enable the port:
configure terminal int eth1/27 do term mon no shut
Show all VLANs in the switch database:
show vlan
Show all the trunked ports on the switch:
show interface trunk
Create VLAN10 and name it ‘CorpVLAN’:
configure terminal vlan 10 name CorpVLAN
Configure a port for access mode – this means there are no trunked VLANs on the switch port but will put the port in one single VLAN that the device connected to it will be in automatically. These commands will select the port, add a description (fileserver), set the port to access mode and put it in VLAN 10:
configure terminal interface Ethernet1/51/1 description fileserver switchport access vlan 10
Configure a port for trunk mode – this means there are trunked VLANs on the switch port. The device you connect to this port will need to understand the trunked VLANs and will most likely be another switch or something like an ESXi host. These commands will select the port, add a description (fileserver), set the port to trunk mode and put it in VLANs 10,20 and 30:
configure terminal interface Ethernet1/38 description fileserver switchport trunk allowed vlan 10,20,30
Show other connected switches:
show cdp neighbor
Configure the switch management port 0, make it a member of vrf management and give it an IP address of 10.20.0.1:
interface mgmt0 vrf member management ip address 10.20.0.1/24 line console line vty
