Second WAN connection to other subnet

Hello

I have a 3900 and a 2960 and I need to use the second WANs to interconnect the two subnets behind each.

The two subnets are in different datacentres but have a 'direct'connection at layer 2 between them.

I am currently simulating this by using a cable to connect the two routers before I install them, but am not having much luck -  what IPs should I be using for the interfaces.

Subnet 1 is 10.10.10.0/24
Subnet 2 is 10.10.11.0/24

They both connect to the internet and can VPN between them if required, but they cannot connect via a cable between the two WANs.

I have tried making the WAN a member of the remote subnet and doing a 'crossover' of the cables so that each WAN can ping the other but the reverse direction doesn't work.

I have tried making the two WANs in a 192.168.1.0/24 subnet and making a static route to show each subnet is available via the other.

The only other option I can think of is to make both sites in the same subnet but then there will be difficulties with traffic routing between the two sites to reach the default gateway.

What should I be trying?

You need to use VLAN and LAN-LAN instead of WANs

Basically you need to make a VLAN on p4 or whichever you plan to use that is within the subnet of the other LAN and this will make it routable from the other LAN.

You only need do this in one direction as the other router should pick it up just with a static route added to the LAN so that the router knows where to look.

See here: https://store.sircles.net/draytek-vigor-39002960-intersiteintern-subnet-communications-via-direct-connection-on-lan-side

According to DrayTek it should just work with LAN RIP active, but we have not seen this actually work so far.