Same VLAN number at multiple sites

[Matt Roberts]

Most of our remote locations are L2, but I need to enable L3 on them and put them all on different subnets. We have several remote locations and I was wondering can I use the same VLAN numbers at each location if they are on different subnets? For example

Site A
vlan 100 - Management 10.1.0.0/24
Vlan 102 - Data 10.1.2.0/24

Site B
Vlan 100 - Management 10.2.0.0/24
Vlan 102 - Data 10.2.2.0/24

Is this a bad idea, should each remote location be on a different vlan? Doesn't the VLAN tag get removed once the traffic is routed? What if I'm routing using an SVI, I have to allow the VLAN through the trunk to keep the SVI up. 

[jhager001]

Yes you can, there is no VLAN tagging over a L3 link, therefor you can have the exact same VLAN's at every site with different subnets, since the subnets are being routed, not the VLAN ID

[Matt Roberts]

To keep the SVI up I would have to allow the VLAN over the trunk link so this will not cause an issue?

[Jon Marshall]

Matt

If they are different vlans your links should be L3 not trunks.

For the data vlans as long as there is a client port up/up then your SVI will be up/up.

Your management vlan however won't be up if you have no trunks.

If there are no trunks to other switches within each site then use a loopback rather than an SVI for management.

If there are other switches in each site connected to the L3 switch then an SVI for management will work.

Jon