I'm setting up a Ubuntu Server 11.10 box with multiple Ethernet interfaces that are bonded for redundancy. I'm planning to use it as a KVM host, so I'll need a network bridge.

To accomplish this, I installed ifenslave and bridge-utils, then wrote my /etc/network/interfaces file. The relevant portion is as follows:

auto br0
iface br0 inet static
    bridge_ports bond0
    bridge_stp off

iface bond0 inet manual
    bond-slaves eth0 eth3
    bond_mode balance-rr
    bond_miimon 100

Unfortunately, this isn't giving me connectivity. ifup br0 gives me "can't add bond0 to bridge br0: Invalid argument", and ifdown br0 gives me "device bond0 is not a slave of br0". If I modify my interfaces file to get rid of the bridge, I have full connectivity—but I'm going to need the bridge.

I think something in my interfaces file is wrong, but I don't know how to make it right. Does anyone know? Thanks!

  • Did you actually find a satisfactory answer or get this working? If so please provide your solution. I'm wanting to do exactly the same thing but with DHCP
    – hookenz
    Mar 26, 2012 at 19:26
  • Sorry, the project ended up being abandoned for awhile. I'll look back into it.
    – Taymon
    Mar 26, 2012 at 22:47
  • The answer you're looking for, several years late, is you're missing an auto statement. Your file should look like auto bond0, the bond0 definition, auto br0, then the br0 definition.
    – Diablo-D3
    Apr 8, 2015 at 10:32
  • @diablo-D3, auto doesnt help. I have the same problem.
    – eos
    Mar 23, 2016 at 14:21
  • @eos In the example op gave, there are also no matching lines to bring the bridge members up. This is also a common configuration error. Listing bond-slaves doesn't up them.
    – Diablo-D3
    Apr 12, 2016 at 19:52

2 Answers 2


This is how I configured a Ubuntu 10.04 LTS system for bridging on top of bonded interfaces:

iface eth0 inet manual
iface eth5 inet manual

# eth0 & eth5 form bond0 for the x.y.z.0/25 subnet
auto bond0
iface bond0 inet static
        bond_miimon 100
        bond_mode active-backup
        bond_downdelay 200
        bond_updelay 200
    address x.y.z.35
    network x.y.z.0
    post-up ifenslave bond0 eth0 eth5
    pre-down ifenslave -d bond0 eth0 eth5

auto br0
iface br0 inet static
    bridge_ports bond0
    address x.y.z.35
    network x.y.z.0
    gateway x.y.z.126

You can try to add this lines to definition of br0 interface:

    pre-up ifup bond0
    post-down ifdown bond0

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