Create 802.1Q trunk interface

[gscalia01]

Hi,

We have a small site with a single L2 3850 switch connecting to an CE router. Currently there is two vlans (2 & 3) on the switch and the interface g1/0/1 connecting to the CE router is only an access port for vlan 2 traffic. We now need to carry traffic from both vlans (2 &3) and I need to create a 802.1Q trunk between the CE router and the 3850 switch.

Is it just a matter of change the int g1/0/1 from an access port to trunk port  on the switch side?  of course the CE would need to do the same  as well.

Please advise.

Thanks,

Jack

[Reza Sharifi]

Hi,

Is it just a matter of change the int g1/0/1 from an access port to trunk port  on the switch side?  of course the CE would need to do the same  as well.

Yes, that is correct.  In addition to changing it to trunk, it is also good practice to add the specific vlans you want to the trunk port.

Example:

switchport mode trunk

switchport trunk allowed vlan 2,3

HTH
 

[chintalamuniraju]

HI 

I hope this will work for you !

Thank you 

CRaju

[jeremykearney]

Jack,

The switch port would be configured with dot1q encapsulation and then set to trunk mode.  The router would need sub interfaces for each vlan with the appropriate encapsulation applied.  You should also consider the native vlan.

Switch:

int gi1/0/1

switchport trunk encapsulation dot1q

switchport mode trunk

Router:

int gi1.2 (you didn't specify the router interface, use what is appropriate for your environment here)

encapsulation dot1q 2

int gi1.3 (same as the previous sub interface)

encapsulation dot1q 3

HTH,

Jeremy