router bgp 65538
  no bgp ebgp-requires-policy
  no bgp network import-check
  neighbor 192.168.255.1 remote-as 65537
  address-family ipv4 unicast
   network 172.31.3.0/24 route-map rmapout
   network 172.31.4.0/24 route-map rmapout
   neighbor 192.168.255.1 route-map rmapin in
   neighbor 192.168.255.1 activate
  exit-address-family
exit
bgp as-path access-list only65540 permit _65540_
bgp as-path access-list only1_4 permit _1.4_
access-list 172311 permit 172.31.1.0/24
access-list 172312 permit 172.31.2.0/24
route-map rmapout permit 1
 set as-path prepend 65540
exit
route-map rmapin permit 1
 match ip address 172311
 match as-path only65540 
exit
route-map rmapin permit 2
 match ip address 172312
 match as-path only1_4 
exit