Yes. It is a pyramid structure.
1
|-------|-------|
2 3 4
The ISP routes 2, 3, 4 with next hop of 1. 2, 3, 4 manage their own firewalls/routers and expose their own IPs. So, I need 1 to behave like a router for 2, 3, 4.
It is like a transport network between routers.