I have 3 device for feeding net to my Router WNDR4700 they are
(a) WAN (wan, wan6) (when it goes it goes down it will be like for month ++)
(b) USB-RNDIS-4G-Router (RNDIS, RNDIS6)
(c) My-Android-Phone (I use it occasionally when (a) and (b) are down or slow ) Note: both (b) and (c) are usb devices but named internally as eth1 and usb0 respectively.
So between (b) and (c), I want to write whenever I connect My-Android-Phone the (b) should be disable and connect when I disconnect My-Android-Phone
(c) My-Android-Phone has following output at $dmesg | tail -3
$dmesg
[ 105.568133] usb 2-1: USB disconnect, device number 3
[ 105.858105] usb 2-1: new high-speed USB device number 4 using xhci_hcd
[ 105.990166] rndis_host 2-1:1.0 usb0: register 'rndis_host' at usb-0000:45:00.0-1, RNDIS device, 0Z:Z0:CC:XX:RR:73