> http://bugme.osdl.org/show_bug.cgi?id=3992
> 
>            Summary: Bondig. Not correct work function ARP Monitoring. Broken
>                     link.
>     Kernel Version: 2.6.10
>             Status: NEW
>           Severity: normal
>              Owner: jgarzik@pobox.com
>          Submitter: stanislav@muhachev.petro.ru
> 
...
> 
> bonding vpn1 & vpn2 то bond0 (bonding default setup -> nothing failover 
> setings)
> link ок!(192.168.100.1-192.168.100.2)
> 
> setting arp monitor in bonding (TUN/TAP driver not support Mii status)
> link down!

I am not sure I understand your setup completely ...
But as stated in bonding.txt, the ARP monitor requires the underlying
driver to update dev->trans_start and dev->last_rx.

Since the TUN/TAP driver doesn't maintain these, it could very well
explain the behavior you are seeing.

The patch below adds the required functionality to the TUN/TAP driver.
Please test if this helps in your case.

-Tommy