Chapter 11. Configuring a network bridge

Procedure

1. Create a bridge interface:

   # nmcli connection add type bridge con-name bridge0 ifname bridge0

   This command creates a bridge named bridge0, enter:

2. Display the network interfaces, and note the names of the interfaces you want to add to the bridge:

   # nmcli device status
   DEVICE  TYPE      STATE         CONNECTION
   enp7s0  ethernet  disconnected  --
   enp8s0  ethernet  disconnected  --
   bond0   bond      connected     bond0
   bond1   bond      connected     bond1
   ...

   In this example:

   • enp7s0 and enp8s0 are not configured. To use these devices as ports, add connection profiles in the next step.
   • bond0 and bond1 have existing connection profiles. To use these devices as ports, modify their profiles in the next step.

3. Assign the interfaces to the bridge.

   1. If the interfaces you want to assign to the bridge are not configured, create new connection profiles for them:

      # nmcli connection add type ethernet slave-type bridge con-name bridge0-port1 ifname enp7s0 master bridge0
      # nmcli connection add type ethernet slave-type bridge con-name bridge0-port2 ifname enp8s0 master bridge0

      These commands create profiles for enp7s0 and enp8s0, and add them to the bridge0 connection.

   2. If you want to assign an existing connection profile to the bridge, set the master parameter of these connections to bridge0:

      # nmcli connection modify bond0 master bridge0
      # nmcli connection modify bond1 master bridge0

      These commands assign the existing connection profiles named bond0 and bond1 to the bridge0 connection.

4. Configure the IP settings of the bridge. Skip this step if you want to use this bridge as a ports of other devices.

   1. Configure the IPv4 settings. For example, to set a static IPv4 address, network mask, default gateway, DNS server, and DNS search domain of the bridge0 connection, enter:

      # nmcli connection modify bridge0 ipv4.addresses '192.0.2.1/24'
      # nmcli connection modify bridge0 ipv4.gateway '192.0.2.254'
      # nmcli connection modify bridge0 ipv4.dns '192.0.2.253'
      # nmcli connection modify bridge0 ipv4.dns-search 'example.com'
      # nmcli connection modify bridge0 ipv4.method manual

   2. Configure the IPv6 settings. For example, to set a static IPv6 address, network mask, default gateway, DNS server, and DNS search domain of the bridge0 connection, enter:

      # nmcli connection modify bridge0 ipv6.addresses '2001:db8:1::1/64'
      # nmcli connection modify bridge0 ipv6.gateway '2001:db8:1::fffe'
      # nmcli connection modify bridge0 ipv6.dns '2001:db8:1::fffd'
      # nmcli connection modify bridge0 ipv6.dns-search 'example.com'
      # nmcli connection modify bridge0 ipv6.method manual

5. Optional: Configure further properties of the bridge. For example, to set the Spanning Tree Protocol (STP) priority of bridge0 to 16384, enter:

   # nmcli connection modify bridge0 bridge.priority '16384'

   By default, STP is enabled.

6. Activate the connection:

   # nmcli connection up bridge0

7. Verify that the ports are connected, and the CONNECTION column displays the port’s connection name:

   # nmcli device
   DEVICE   TYPE      STATE      CONNECTION
   ...
   enp7s0   ethernet  connected  bridge0-port1
   enp8s0   ethernet  connected  bridge0-port2

   Red Hat Enterprise Linux activates controller and ports when the system boots. By activating any port connection, the controller is also activated. However, in this case, only one port connection is activated. By default, activating the controller does not automatically activate the ports. However, you can enable this behavior by setting:

   1. Enable the connection.autoconnect-slaves parameter of the bridge connection:

      # nmcli connection modify bridge0 connection.autoconnect-slaves 1

   2. Reactivate the bridge:

      # nmcli connection up bridge0

Procedure

1. Open a terminal, and enter nm-connection-editor:

   $ nm-connection-editor

2. Click the + button to add a new connection.
3. Select the Bridge connection type, and click Create.

4. In the Bridge tab:

   1. Optional: Set the name of the bridge interface in the Interface name field.

   2. Click the Add button to create a new connection profile for a network interface and adding the profile as a port to the bridge.

      1. Select the connection type of the interface. For example, select Ethernet for a wired connection.
      2. Optionally, set a connection name for the port device.
      3. If you create a connection profile for an Ethernet device, open the Ethernet tab, and select in the Device field the network interface you want to add as a port to the bridge. If you selected a different device type, configure it accordingly.
      4. Click Save.

   3. Repeat the previous step for each interface you want to add to the bridge.

      

5. Optional: Configure further bridge settings, such as Spanning Tree Protocol (STP) options.

6. Configure the IP settings of the bridge. Skip this step if you want to use this bridge as a port of other devices.

   1. In the IPv4 Settings tab, configure the IPv4 settings. For example, set a static IPv4 address, network mask, default gateway, DNS server, and DNS search domain:

      

   2. In the IPv6 Settings tab, configure the IPv6 settings. For example, set a static IPv6 address, network mask, default gateway, DNS server, and DNS search domain:

      

7. Save the bridge connection.
8. Close nm-connection-editor.

Procedure

1. Create a YAML file, for example ~/create-bridge.yml, with the following contents:

   ---
   interfaces:
   - name: bridge0
     type: linux-bridge
     state: up
     ipv4:
       enabled: true
       address:
       - ip: 192.0.2.1
         prefix-length: 24
       dhcp: false
     ipv6:
       enabled: true
       address:
       - ip: 2001:db8:1::1
         prefix-length: 64
       autoconf: false
       dhcp: false
     bridge:
       options:
         stp:
           enabled: true
       port:
         - name: enp1s0
         - name: enp7s0
   - name: enp1s0
     type: ethernet
     state: up
   - name: enp7s0
     type: ethernet
     state: up
   
   routes:
     config:
     - destination: 0.0.0.0/0
       next-hop-address: 192.0.2.254
       next-hop-interface: bridge0
     - destination: ::/0
       next-hop-address: 2001:db8:1::fffe
       next-hop-interface: bridge0
   dns-resolver:
     config:
       search:
       - example.com
       server:
       - 192.0.2.200
       - 2001:db8:1::ffbb

2. Apply the settings to the system:

   # nmstatectl apply ~/create-bridge.yml

Verification steps

1. Display the status of the devices and connections:

   # nmcli device status
   DEVICE      TYPE      STATE      CONNECTION
   bridge0     bridge    connected  bridge0

2. Display all settings of the connection profile:

   # nmcli connection show bridge0
   connection.id:              bridge0
   connection.uuid:            e2cc9206-75a2-4622-89cf-1252926060a9
   connection.stable-id:       --
   connection.type:            bridge
   connection.interface-name:  bridge0
   ...

3. Display the connection settings in YAML format:

   # nmstatectl show bridge0