iRule for using SNAT and Next-Hop for specific pool member only

you can enable/disable snat after server is selected in LB_SELECTED.

e.g.

 floating self ip (snat automap)

root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list net self 200.200.200.14/24
net self 200.200.200.14/24 {
    address 200.200.200.14/24
    allow-service {
        default
    }
    floating enabled
    traffic-group traffic-group-1
    unit 1
    vlan internal
}

 config

root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm virtual bar
ltm virtual bar {
    destination 172.28.24.10:80
    ip-protocol tcp
    mask 255.255.255.255
    pool foo
    profiles {
        http { }
        tcp { }
    }
    rules {
        qux
    }
    source 0.0.0.0/0
    source-address-translation {
        type automap
    }
    vs-index 41
}
root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm pool foo
ltm pool foo {
    members {
        200.200.200.101:80 {
            address 200.200.200.101
        }
        200.200.200.111:80 {
            address 200.200.200.111
        }
    }
}
root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm rule qux
ltm rule qux {
    when LB_SELECTED {
  switch [LB::server addr] {
    200.200.200.101 { snat automap }
    default { snat none }
  }
}
when SERVER_CONNECTED {
  log local0. "[IP::local_addr]:[TCP::local_port] > [IP::remote_addr]:[TCP::remote_port]"
}
}

 test

[root@ve11a:Active:In Sync] config  tail -f /var/log/ltm
Jun  5 07:56:09 ve11a info tmm1[9801]: Rule /Common/qux SERVER_CONNECTED: 200.200.200.14:44267 > 200.200.200.101:80
Jun  5 07:56:11 ve11a info tmm[9801]: Rule /Common/qux SERVER_CONNECTED: 172.28.24.1:44268 > 200.200.200.111:80