What VLANS does this port have access to?

[adamwilkinson776321465]

Hi,

If the config says switchport mode trunk  does this mean the port has access to all of the vlans on the switch?

Any help appreciated please

#show running-config interface gi1/0/23
Building configuration...

Current configuration : 185 bytes
!
interface GigabitEthernet1/0/23
switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate
spanning-tree portfast disable
channel-group 1 mode active
end

[Nadav]

It can send all configured VLANs over the trunk. If you want to select specific VLANs, use "switchport trunk allowed vlan <vlans>"

[Jaderson Pessoa]

Hello

this command apply all vlans configured on switch itself. If you want to see what vlans are allowed trough this interface, use this command.

"show interface gi 1/0/23 trunk"

If you want allow a list of vlans, you can use a command like below;

"switchport trunk allowed vlan 10,20,30-50"

Best regards,

[luis_cordova]

Hi @adamwilkinson776321465 

When a frame reaches a switch, the number of vlan(tag) configured in the interface is inserted.

Then, that frame is switched to all ports that have the same tag assigned.

When you configure a port in trunk mode, the switch will include that port when switching frames originating from different vlan. This is necessary in the links that connect two switches and in the links that connect a switch to a router.

Regards