NetworkManager and bridging

Friday , 20, December 2013 6 Comments

In previous iterations of NetworkManager, it was really only useful if you were dealing with wireless networks. Anything involving a bridge meant removing the device from NetworkManager, and manually configuring the network.

A fair amount of work has been done to make NetworkManager more friendly to bridged devices, however it's still far from perfect.    My experiences so far:

  • There isn't an intuitive way to create a bridge in the NetworkManager gui.
  • Configuring the bridge manually, and leaving control of the devices with NetworkManager works. I tested this using bridged network devices and virtual machines in virt-manager.
  • With a manually configured bridge, the status icon in gnome is confused at best. Do not rely on it to provide an accurate status of your network.

The screenshot below should demonstrate the confusion to some extent. I wouldn't expect the 'Wired' connection to show up, as it's a slave to the bridge. Both the virbr0 and the vpn show as off, even though both are active and in use.

network-manager

At this point the best course of action for anyone who needs a bridge is simply to remove NetworkManager from the equation. Since this is already current practice, it's not really a deviation for folks tracking 6->7 differences.

6 thoughts on “ : NetworkManager and bridging”
  • Mika Ilmaranta says:

    Have You been able to get bond devices up and running without NetworkManager?

  • Yogesh says:

    One can use NM to setup bridge:

    Here are steps
    1 Applications -> System Tools -> Settings -> Network
    2 Disable existing wired Network
    3 Add new bridge connection
    4 In popup dialog general tab ensure "Connect Auto" is checked
    5 "Bridged connections" Add
    6 In popup dialog general tab ensure "Connect Auto" is checked
    7 From Device MAC dropdown select MAC of your existing wired network ( which was disabled in step #2)
    8 Finish by clicking save on all the dialogs

    Bridge should be working now except (as you wrote icon shows wrong state)

  • Is Bridging nessasary when creating vlans in libvirt ? or does libvirt create the bridges itzelf ?

  • serg says:

    Open the Terminal app
    Get info about the current connection:
    nmcli con show
    Add a new bridge:
    nmcli con add type bridge ifname br0
    Create a slave interface:
    nmcli con add type bridge-slave ifname eno1 master br0
    Turn on br0:
    nmcli con up br0

    https://www.cyberciti.biz/faq/how-to-add-network-bridge-with-nmcli-networkmanager-on-linux/

  • Akemi Yagi says:

    There is a CentOS wiki article, "Setting up a network bridge using nmcli on CentOS 7"

    https://wiki.centos.org/TipsAndTricks/BridgeAndNmcli

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