How to connect 3 Cisco routers via VPN?

Question

VPN

In general essence of a problem
I need to connect 3 cities through Cisco VPN routers. Especially never with these routers did not work.
I tried to connect via Gre, but I just can’t connect 3 routers.
I was able to connect 1 and 2 via GRE, hung up ospf routing, all hosts see each other, but 3 router does not work at all.
Who knows how to do it, tell me where to dig? and what vpn method of a tsiska to use for expansion of a network up to 100 branches. Please don’t kick me, I’m doing a lab I’m
attaching the scheme, star topology, 2 central router


R1 - mirror settings on R2 router
ip route 0.0.0.0 0.0.0.0 10.1.100.1
interface tunnel 0
tunnel mode gre ip
ip address 10.10.0.1 255.255.255.0
tunnel source fastEthernet 0/0
tunnel destination 10.2.100.2
OSPF 1R
conf t
router ospf 1
router-id 1.1.1.1
network 10.88.30.0 0.0.0.255 area 0
network 10.10.0.0 0.0.0.255 area 0

Answer 1

is GRE necessary? it is quite enough that the top one knows how to L3 routing and it has interfaces of each VLAN with addresses. then, when routing is enabled, even routes do not need to be registered, it is enough to specify the addresses of its interfaces with gateways.
if you need to encrypt traffic, you will have to raise at least three tunnels for the drawn scheme. IMHO.