7.4. Using the Command Line Interface (CLI)
A bond is created using the
bonding kernel module and a special network interface called a channel bonding interface.
7.4.1. Check if Bonding Kernel Module is Installed
In Red Hat Enterprise Linux 7, the bonding module is not loaded by default. You can load the module by issuing the following command as
root:
~]# modprobe --first-time bonding
This activation will not persist across system restarts. See the Red Hat Enterprise Linux Kernel Administration Guide for an explanation of persistent module loading. Note that given a correct configuration file using the BONDING_OPTS directive, the bonding module will be loaded as required and therefore does not need to be loaded separately.
To display information about the module, issue the following command:
~]$ modinfo bonding
See the modprobe(8) man page for more command options.
7.4.2. Create a Channel Bonding Interface
To create a channel bonding interface, create a file in the
/etc/sysconfig/network-scripts/ directory called ifcfg-bondN, replacing N with the number for the interface, such as 0.
The contents of the file can be based on a configuration file for whatever type of interface is getting bonded, such as an Ethernet interface. The essential differences are that the
DEVICE directive is bondN, replacing N with the number for the interface, and TYPE=Bond. In addition, set BONDING_MASTER=yes.
Example 7.1. Example ifcfg-bond0 Interface Configuration File
An example of a channel bonding interface.
DEVICE=bond0 NAME=bond0 TYPE=Bond BONDING_MASTER=yes IPADDR=192.168.1.1 PREFIX=24 ONBOOT=yes BOOTPROTO=none BONDING_OPTS="bonding parameters separated by spaces" NM_CONTROLLED="no"
The NAME directive is useful for naming the connection profile in NetworkManager. ONBOOT says whether the profile should be started when booting (or more generally, when auto-connecting a device).
Important
Parameters for the bonding kernel module must be specified as a space-separated list in the
BONDING_OPTS="bonding parameters" directive in the ifcfg-bondN interface file. Do not specify options for the bonding device in /etc/modprobe.d/bonding.conf, or in the deprecated /etc/modprobe.conf file.
The
max_bonds parameter is not interface specific and should not be set when using ifcfg-bondN files with the BONDING_OPTS directive as this directive will cause the network scripts to create the bond interfaces as required.
For further instructions and advice on configuring the bonding module and to view the list of bonding parameters, see Section 7.7, “Using Channel Bonding”.
Note that if the
NM_CONTROLLED="no" setting is not present, NetworkManager might override settings in this configuration file.
7.4.3. Creating Port Interfaces
The channel bonding interface is the controller (also refered to as
master) and the interfaces to be bonded are referred to as the ports (slaves). After the channel bonding interface is created, the network interfaces to be bound together must be configured by adding the MASTER and SLAVE directives to the configuration files of the ports. The configuration files for each of the port interfaces can be nearly identical.
Example 7.2. Example Port Interface Configuration File
For example, if two Ethernet interfaces are being channel bonded,
enp1s0 and enp2s0, they can both look like the following example:
DEVICE=device_name NAME=bond0-slave TYPE=Ethernet BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes NM_CONTROLLED="no"
In this example, replace device_name with the name of the interface. Note that if more than one profile or configuration file exists with
ONBOOT=yes for an interface, they may race with each other and a plain TYPE=Ethernet profile may be activated instead of a bond port.
Note
Note that if the
NM_CONTROLLED="no" setting is not present, NetworkManager might override settings in this configuration file.
7.4.4. Activating a Channel Bond
To activate a bond, open all the ports. As
root, issue the following commands:
~]# ifup ifcfg-enp1s0
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/7)
~]# ifup ifcfg-enp2s0
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/8)
Note that if editing interface files for interfaces which are currently “up”, set them down first as follows:
ifdown device_nameThen when complete, open all the ports, which will open the bond (provided it was not set “down”).
To make NetworkManager aware of the changes, issue a command for every changed interface as
root:
~]# nmcli con load /etc/sysconfig/network-scripts/ifcfg-device
Alternatively, to reload all interfaces:
~]# nmcli con reload
The default behavior is for NetworkManager not to be aware of the changes and to continue using the old configuration data. This is set by the monitor-connection-files option in the NetworkManager.conf file. See the NetworkManager.conf(5) manual page for more information.
To view the status of the bond interface, issue the following command:
~]# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp1s0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master bond0 state UP mode DEFAULT qlen 1000
link/ether 52:54:00:e9:ce:d2 brd ff:ff:ff:ff:ff:ff
3: enp2s0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master bond0 state UP mode DEFAULT qlen 1000
link/ether 52:54:00:38:a6:4c brd ff:ff:ff:ff:ff:ff
4: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT
link/ether 52:54:00:38:a6:4c brd ff:ff:ff:ff:ff:ff
7.4.5. Creating Multiple Bonds
In Red Hat Enterprise Linux, for each bond a channel bonding interface is created including the
BONDING_OPTS directive. This configuration method is used so that multiple bonding devices can have different configurations. To create multiple channel bonding interfaces, proceed as follows:
- Create multiple
ifcfg-bondNfiles with theBONDING_OPTSdirective; this directive will cause the network scripts to create the bond interfaces as required. - Create, or edit existing, interface configuration files to be bonded and include the
SLAVEdirective. - Assign the interfaces to be bonded, the port interfaces, to the channel bonding interfaces by means of the
MASTERdirective.
Example 7.3. Example multiple ifcfg-bondN interface configuration files
The following is an example of a channel bonding interface configuration file:
DEVICE=bondN NAME=bondN TYPE=Bond BONDING_MASTER=yes IPADDR=192.168.1.1 PREFIX=24 ONBOOT=yes BOOTPROTO=none BONDING_OPTS="bonding parameters separated by spaces"
In this example, replace N with the number for the bond interface. For example, to create two bonds create two configuration files,
ifcfg-bond0 and ifcfg-bond1, with appropriate IP addresses.
Create the interfaces to be bonded as per Example 7.2, “Example Port Interface Configuration File” and assign them to the bond interfaces as required using the
MASTER=bondN directive. For example, continuing on from the example above, if two interfaces per bond are required, then for two bonds create four interface configuration files and assign the first two using MASTER=bond0 and the next two using MASTER=bond1.
