slb server rs_172.16.0.5 172.16.0.5
   port 80  tcp
slb server rs_172.16.0.6 172.16.0.6
   port 80  tcp
!
slb service-group test tcp
    member rs_172.16.0.5:80
    member rs_172.16.0.6:80
!
!
slb virtual-server vip_172.16.0.21 172.16.0.21
   port 80  tcp
      source-nat pool snat_pool
      service-group test