The same VLans at WAN and LAN interfaces

[Safar Safarov]

I have VLans 20 and 21 set by ISP for Voice and Data respectively.

What will happen if I already have VLans 20 and 21 in my Local network?

[andrew.prince · Accepted solution]

you can have secondary ip addresses

Sent from Cisco Technical Support iPad App

[Safar Safarov]

Ok. Thanks a lot )

[mousmani]

This will affect spanning-tree bridge election and layer2 convergence in your network.

Do not propogate this to your local LAN switches.

Also this will not have any effect if your topology is lke this below :

ISP---TRUNK VLAN20,21----SWITCH-EXTERNAL---ROUTER-----SWITCHES -- YOUR L2 network.

No need for secondary ip address also.

regards,

aslam

[mousmani]

This will affect spanning-tree bridge election and layer2 convergence in your network.

Do not propogate this to your local LAN switches.

Also this will not have any effect if your topology is lke this below :

ISP---TRUNK VLAN20,21----SWITCH-EXTERNAL---ROUTER-----SWITCHES -- YOUR L2 network.

No need for secondary ip address also.

regards,

aslam