We have installed two radio link with basebox 5 . there are four radio. location one R1-192.168.254.102 R3- 192.168.245.71 and location two R2-192.168.254.103, R4-192.168.245.70. at location one we have server having ip 192.168.10.39 . from another location users are accessing this server. we want to make failover and load balancing script in this two links. i am planning to put RB750 at location two. wan1 will be R2 wan2 will be R4. so how can i do failover. and load balancing. all location desktop ip address in same range. i.e 192.168.10.xxx

Thanks in advance....

Use OSPF with EQMP load balancing. No scripts required.

*whoops - ECMP (equal cost multi-path)

The wiki should have some articles about OSPF examples. If you create two paths between a pair of routers, and the cost of each path is the same, then OSPF will automatically load-balance the two (roughly - it's not as well-balanced as other protocols such as LACP can do, but LACP/PAGP/etc require identical links, and wireless just can't do that)

Please find details diagram. please help

R1 R2 R3 and R4 should all be configured as bridges.

On site 1:
/routing ospf
instance set 0 router-id=1.1.1.1
interface add interface=ether3 passive=yes
network
add area=backbone network=192.168.254.0/24
add area=backbone network=192.168.245.0/24
add area=backbone network=192.168.10.0/24

On site 2:
/routing ospf
instance set 0 router-id=2.2.2.2
interface add interface=ether3 passive=yes
network
add area=backbone network=192.168.254.0/24
add area=backbone network=192.168.245.0/24
add area=backbone network=192.168.20.0/24

That's all you need.