Combine multiple interfaces with network bonding¶

This guide describes how to configure systemd to use the bonding driver.

Network bonding combines multiple network interfaces into a single logical interface to provide redundancy and bandwidth aggregation.

Clear Linux* OS includes the Linux Bonding driver and Team driver .

The example demonstrates how to:

Bond all four ports of a quad-port NIC in 802.3ad mode.
Enable jumbo frames to optimize large data transfers on the local network.

Your NICs and network switch must support 802.3ad mode and jumbo frames. The example explains how to configure your NICs for both features. Your switch may require additional configuration. See your switch documentation for details.

Note

You must run all commands in this guide as root.

Log in and get root privileges.
```
sudo -s
```
Create the /etc/systemd/network directory.
```
mkdir -p /etc/systemd/network
```
The /etc/systemd/network directory contains configuration files and network settings for the virtual device and its underlying physical interfaces.
Configure systemd to create a virtual network device called bond1. Use a text editor to create a file named 30-bond1.netdev.
```
[NetDev]
Name=bond1
Kind=bond

[Bond]
Mode=802.3ad
TransmitHashPolicy=layer3+4
MIIMonitorSec=1s
LACPTransmitRate=fast
```
Refer to the systemd.netdev manpage for 30-bond1.netdev file syntax. This example is based on Example 9 on the manpage. Modify the example for your configuration.
Configure the slave interfaces. Create a text file named 30-bond1-enp1s0.network. Assign the slave interfaces to the virtual bond1 device and use the syntax shown in systemd.network.
```
[Match]
Name=enp1s0f*

[Network]
Bond=bond1

[Link]
MTUBytes=9000
```
The example bonds all four ports of a quad-port NIC as a slave of bond1. The example uses a wildcard match because the NIC names are in the range enp1s0f0-enp1s0f3. If your NIC names are not wildcard-compatible, create a separate .network file for each NIC.

For best results, do not assign addresses or DHCP support to the individual NICs.

The MTUBytes setting enables jumbo frames of up to 9000 bytes. Your switch may require additional configuration to support this setting.
Configure the bonded interface in a file named 30-bond1.network.
```
[Match]
Name=bond1

[Network]
BindCarrier=enp1s0f0 enp1s0f1 enp1s0f2 enp1s0f3
Address=192.168.1.201/24

[Link]
MTUBytes=9000
```
bond1 is a virtual interface with no physical link status.

BindCarrier indicates that the bond1 link status is determined by the status of the listed slave devices.

Address contains an IP address that you assign to the logical interface. DHCP bonded interfaces are complex and outside the scope of this example.

MTUBytes must be set to 9000 on all slave interfaces and on the bonded interface for successful jumbo frames operation. If MTUBytes is not the same on all interfaces, then the lowest value is used.
Apply the new network configuration with the command:
```
systemctl restart systemd-networkd
```
The MTUBytes settings do not take effect until you reboot or manually apply the settings with a utility such as ifconfig.