Comment 3 for bug 920217

I have got a similar problem, this is my old setup:

auto eth0
iface eth0 inet manual

auto eth1
iface eth1 inet manual

auto bond0
iface bond0 inet manual
        bond-mode 4
        bond-miimon 100
        xmit_hash_policy layer2+3
        lacp_rate slow
        slaves eth0 eth1

related to: http://ubuntuforums.org/showthread.php?t=1876061
and to: /usr/share/doc/ifenslave-2.6/README.Debian.gz

I changed my network/interfaces file to

auto bond0
iface bond0 inet manual
        bond-slaves none
        bond-mode 802.3ad
        bond-ad_select bandwidth
        bond-lacp_rate slow
        bond-miimon 100
        bond-use_carrier 1
        bond-downdelay 200
        bond-updelay 200
        bond-primary eth0 eth1

auto eth0
allow-bond0 eth0
iface eth0 inet manual
   bond-master bond0
   bond-primary eth0 eth1

auto eth1
allow-bond0 eth1
iface eth1 inet manual
   bond-master bond0
   bond-primary eth0 eth1

and now it works. It would be nice to have got a bonding example in the ubuntu free documentation.