Configure NIC(Network Interface Card) bonding in CentOS 7 / RHEL 7 NIC(Network Interface Card) bonding is also known as Network bonding. It can be defined as the aggregation or combination of multiple NIC into a single bond interface. It’s main purpose is to provide high availability and redundancy. In this article we will learn how to configure nic or netwok bonding in CentOS 7 & RHEL 7. In my case i have two interface cards (enp0s3 & enp0s8) and will form a bond interface (bond0). Prerequisite : If bonding module is not loaded on your linux box then use the below command to load. [root@openstack ~]# modprobe bonding To list the bonding module info, use following command. [root@openstack ~]# modinfo bonding Output will be something like below Step:1 Create Bond Interface File Create a bond interface file (ifcfg-bond0) under the folder “/etc/sysconfig/network-scripts/” [root@openstack network-scripts]# vi ifcfg-bond0 DEVICE=bond0 TYPE=Bond NAME=bond0 BONDING_MASTER=yes BOOTPROTO=none ONBOOT=yes IPADDR=192.168.1.70 NETMASK=255.255.255.0 GATEWAY=192.168.1.1 BONDING_OPTS="mode=5 miimon=100" Save & exit the file. Specify the IP address, Netmask & bonding modes as per your requirement. In my example i am using ‘mode=5′ which is used to provide fault tolerance and load balancing. Step:2 Edit the NIC interface files For ifcfg-enp0s3 [root@openstack ~]# vi /etc/sysconfig/network-scripts/ifcfg-enp0s3 TYPE=Ethernet BOOTPROTO=none DEVICE=enp0s3 ONBOOT=yes HWADDR="08:00:27:69:60:c9" MASTER=bond0 SLAVE=yes For ifcfg-enp0s8 [root@openstack ~]# cat /etc/sysconfig/network-scripts/ifcfg-enp0s8 TYPE=Ethernet BOOTPROTO=none DEVICE=enp0s8 ONBOOT=yes HWADDR="08:00:27:ea:71:8d" MASTER=bond0 SLAVE=yes Step:3 Restart the Network Service Below command will restart the network service and will bring above changes into the effect. [root@openstack ~]# systemctl restart network.service Step:4 Test & Verify bond interface. Use ‘ifconfig‘ & ‘ip add‘ command to check bond interface along with its slave interfaces. Use following command to view bond interface settings like bonding mode & slave interface. [root@openstack ~]# cat /proc/net/bonding/bond0 Step:5 Fault tolerance testing To test the fault tolerance we can down one interface and check whether you are still able access the server. [root@openstack ~]# ifdown enp0s8 Device 'enp0s8' successfully disconnected. [root@openstack ~]# www.hackthesec.co.in www.twitter.com/hackthesecurity