What is the best protocol?

Question

Computer networks

Good morning!
I need your help with choosing a routing protocol and in general with setting up a scalable network.
There are:
2 servers
1 in Moscow (main)
1 in St. Petersburg (reserve)
400+ routers (soho)
Openvpn (tap) service to weigh on two servers, routers are connected to it.
Task:
1) See the network behind the router
2) The network must be visible on two servers.

Answer 1

In such a scheme, RIP is also suitable (and perhaps it will be the best option). You just need to drag the route from the router to the server.
PS Earlier you wrote that you already have OSPF. Didn't take off?