Hey,This just for practicingyou are saying problem is in R3 and in bgp networks?
(R3 bgp network config)
network 172.16.255.248 mask 255.255.255.252
network 172.16.255.252 mask 255.255.255.252
network 10.0.0.0 mask 255.255.255.252
network 10.2.0.252...