Bonding
From PlcWiki
Interface bonding
It is possible to use one IP address for one or more interfaces. It is possible to join wireless and LAN interface together. First of all you have to test both interfaces if they work. To set up wireless interface see steps in Wifi on station. Wireles and Ethernet interface can be bonded in case that both networks are bridged.
To set up bonding of eth0 and wlan0 interfaces in backup mode follow these steps:
1) create configuration of bond0 interface in /etc/sysconfig/network-scripts/ifcfg-bond0
ONBOOT=yes DEVICE=bond0 BONDING_OPTS="miimon=100 mode=active-backup primary=wlan0" BOOTPROTO=none TYPE=Bonding USERCTL=no IPV6INIT=no PEERDNS=no DNS1="x.x.x.x GATEWAY="x.x.x.x" IPADDR="x.x.x.x" NETMASK="x.x.x.x"
2) backup original /etc/sysconfig/network-scripts/ifcfg-eth0 and edit it
ONBOOT=yes SLAVE=yes MASTER=bond0 TYPE=Ethernet DEVICE=eth0 BOOTPROTO=none PEERDNS=yes USERCTL=no IPV6INIT=no
3) backup original /etc/sysconfig/network-scripts/ifcfg-wlan0 and edit it
ONBOOT=yes SLAVE=yes MASTER=bond0 TYPE=Wireless DEVICE=wlan0 BOOTPROTO=none PEERDNS=yes USERCTL=no IPV6INIT=no ESSID="xx" RATE=auto MODE=Managed
4) restart network
service network restart
5) check your interfaces
ifconfig
To check which interface is in use you can use:
cat /proc/net/bonding/bond0
In this configuration is wlan0 master and eth0 backup. I you have access to your wireless network based on MAC addresses check MAC address of bond0 interface. This interface takes MAC address from first bonded interface. It means that in this case it could have MAC of eth0 interface.
