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

Arnaud Fontaine arnau at milkypond.org
Thu Jun 30 12:58:31 PDT 2011


> There are  two flags, IFF_UP  - admin up/down and  IFF_RUNNING carrier
> up/down The IFF_UP is controlled manually, and IFF_RUNNING is what you
> are talking about.

Interesting, thank you very much for the explanation.

> In older  kernel versions, the  bridge device always  asserted carrier
> even if all  ports did not have carrier. Now it  reflects the state of
> the  underlying device.  In  your case  the  problem is  that the  tap
> interfaces aren't reporting carrier.

This  is what  I understood  by testing  with a  real  network interface
attached to the  bridge, however I was not sure  whether it was intended
or a regression.  In this  particular case, a tap interface is reporting
carrier when  an userspace program is  attached to it AFAIK,  so I guess
there  is  nothing else  I  can do  besides  of  attaching an  userspace
program, right?

Thanks for the quick response.

Arnaud Fontaine

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