All routers have a loopback 0 interface X.X.X.X/32 where X is the number of the router.
Configure OSPF on R1, R2, R3 and advertise 10.10.12.0/24, 10.10.13.0/24 and loopback 0 subnets
Configure OSPF on R4, R5 and advertise 126.96.36.199/26 and loopback 0 subnets
Configure full iBGP mesh in AS 123, use loopback 0 interface for peering
Configure iBGP in AS 45, use loopback 0 interface for peering
Configure eBGP between AS 123 and AS 45
Advertise R1 loopback 0 and 188.8.131.52/26 in BGP
Ensure AS 123 will use the link between R3-R5 towards network 184.108.40.206/26. Use MED attribute only.
Ensure AS 45 will use the link between R3-R5 towards network 220.127.116.11/32. Use MED attribute only.