WAN L3 routing and L2 forwarding between 2 sites?

hmc250000 · ‎12-12-2019

Can you have L3 routing and L2 forwarding between 2 sites?

Site A
10.1.1.1/24 vlan4

Site B
172.16.10.0/24 vlan 10
172.16.20.0/24 vlan 20
172.16.30.0/24 vlan 30
172.16.40.0/24 vlan 40

Can you have the sites connected to both a metro ethernet L3 link (OSPF is used to advertise the subnets) and another metro ethernet point to point L2 link (L2 trunk between the switches with all vlans added).
Will L2 automatically take precedence over L3 routing?

Reza Sharifi · ‎12-12-2019

L2 should take precedence over layer-3 but the problem with this type of design is that you would have to change the user gateways every time you fail over from one circuit to the other. So, for example, for site-A the user default gateways for vlan 4 will be 10.1.1.1 when you are running layer-3 and so, when you switch from layer-3 to 2 the gateway would have to be changed from .1 to .2 if site-B is going to be hosting all the SVIs for all the vlans.

HTH