Static IP address
Assigning a static IP address on CentOS is accomplished by editing the files in the directory /etc/sysconfig/network-scripts. For example, assign a static IP address to interface eth0 by editing /etc/sysconfig/network-scripts/ifcfg-eth0:
DEVICE=eth0 BOOTPROTO=none IPADDR=192.168.0.123 NETMASK=255.255.255.0 GATEWAY=192.168.0.1 ONBOOT=yes
Network interface bonding
To achieve higher bandwidth and/or reliability, network interfaces can be bonded. First, edit the file /etc/sysconfig/network-scripts/ifcfg-bond0:
DEVICE=bond0 BOOTPROTO=none IPADDR=10.0.0.1 NETMASK=255.255.255.0 ONBOOT=yes
After that, you need to edit the network interfaces that are part of this bond, e.g. eth1 and eth2. Let’s start with /etc/sysconfig/network-scripts/ifcfg-eth1:
DEVICE=eth1 BOOTPROTO=none MASTER=bond0 SLAVE=yes ONBOOT=yes
Then edit /etc/sysconfig/network-scripts/ifcfg-eth2:
DEVICE=eth2 BOOTPROTO=none MASTER=bond0 SLAVE=yes ONBOOT=yes
The last file to edit is /etc/modprobe.conf:
alias bond0 bonding options bond0 mode=active-backup miimon=100
The mode value in this last file can be one of several:
In the active-backup mode shown in the example, only one slave in the bond is active. A different slave becomes active if, and only if, the active slave fails. The bond’s MAC address is externally visible on only one port (network interface) to avoid confusing the switch.
The option miimon (media-independent interface monitoring) defines how often, in milliseconds, link monitoring occurs.