[Bridge] Bridge interface always down since Linux >= 2.6.39

Arnaud Fontaine arnau at milkypond.org
Thu Jun 30 06:05:36 PDT 2011


After upgrading my  kernel to 2.6.39 (I also  tested with 3.0.0-rc4), my
bridge interface  with only TAP interfaces  is always down  (the flag is
NO_CARRIER and  operational state is  DOWN) despite it was  working well
with  previous  versions of  the  kernel  (the  state was  LOWER_UP  and
operational state  was UNKNOWN). Before, running  the following commands
was enough to activate the bridge interface:

  1. brctl addbr br0
  2. ip link set br0 up

Only by attaching a real network interface (such as eth0) to the bridge,
it finally works well  but I would like to be able  to not only use real
network interfaces.

Any idea? Many thanks in advance.

Arnaud Fontaine

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