How do I setup a bonding device bond0 and enslave two real Ethernet (say eth0 and eth2) devices to it on Ubuntu Linux 140.04 or 16.04 LTS server? How can I create 802.3ad bonding mode (IEEE 802.3ad Dynamic link aggregation) on Ubuntu Linux 16.04 LTS server?

You need to install and use a tool called ifenslave. It will attach and detach slave network devices to a bonding device. The Linux kernel comes with bonding driver which provides a method for aggregating multiple network interfaces into a single logical “bonded” interface. You need bonding to get higher data rates and as well as link failover.

Install ifenslave on Ubuntu

Type the following command:
$ sudo apt install ifenslave

Our sample setup

  • Bonding interface name: bond0
  • Link aggregation type: 802.3ad (mode 4)
  • Physical interfaces: eth0 and eth2 (as per your needs)
  • IP address assigned only to: bond0 (do not assign any IP address to eth0 and eth2 interfaces)

How to setup a bonding device on Ubuntu Linux

The following example shows how to setup a bonding device and enslave two real Ethernet devices to it from command prompt:

  1. Load driver, run: # modprobe bonding
  2. Setup bond0 with an IP address, run: # ifconfig bond0 netmask
  3. Enslave two interfaces, run: # ifenslave bond0 eth0 eth2
  4. Verify it: # ifconfig bond0
  5. View bonding info: # more /proc/net/bonding/bond0

Persistent bond0 configuration

Edit /etc/network/interfaces file, run:
$ sudo vi /etc/network/interfaces
Edit/update your config file as follows:

auto bond0
iface bond0 inet static
# Example add eth0 speed if needed (I'm going with auto detect/nego)
#pre-up /usr/sbin/ethtool -s bond0 speed 1000 duplex full autoneg on
post-up ifenslave bond0 eth0 eth2
pre-down ifenslave -d bond0 eth0 eth2
bond-slaves none
# 802.3ad mode
bond-mode 4
bond-lacp-rate fast
bond-miimon 100
bond-downdelay 0
bond-updelay 0
bond-xmit_hash_policy 1
# Add static route example if you needed #
# up route add -net gateway a.b.c.d
# down route del -net
auto eth0
iface eth0 inet manual
# Example add eth0 speed if needed
#pre-up /usr/sbin/ethtool -s eth0 speed 1000 duplex full autoneg on
auto eth2
iface eth2 inet manual
# Example add eth2 speed if needed
#pre-up /usr/sbin/ethtool -s eth2 speed 1000 duplex full autoneg on

Save and close the file. Restart the the networking service on Ubuntu Linux 14.04 LTS or older:
$ sudo /etc/init.d/networking restart
For Ubuntu Linux 16.04 LTS, enter:
$ sudo systemctl restart networking

Verify new settings

$ ip a show bond0
$ ifconfig bond0
Sample outputs:

6: bond0: <broadcast,multicast,master,up,lower_up> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 00:25:90:4f:b0:6c brd ff:ff:ff:ff:ff:ff
    inet brd scope global bond0
       valid_lft forever preferred_lft forever
    inet6 fe80::225:90ff:fe4f:b06c/64 scope link 
       valid_lft forever preferred_lft forever

To see the current status of Linux kernel bonding driver and bond0 interface type:
$ more /proc/net/bonding/bond0
Sample outputs:

Fig.01: bond0 status