Let Say Router A have 3 clients on eth1 port with x.x.x.x, y.y.y.y, z.z.z.z public ip and eth1 port have t.t.t.t public ip which is acting as gateway for internal network. now eth2 of router A connected with ISP Router which is Router B’s eth1 with a /30 subnet.
now i want to know the router B’s configuration, that means how router B route those static IPs into the Router A’s internal network
With this configuration you need configure:
1.- Route 0.0.0.0/0, gateway (IP from eth1 of router B). On A router.
2.- “masquerade” for internet navigation on Router B.
I think with this configuration you will have intenet navigation.