Comment 9 for bug 974218

OK,
Indeed, after configuring /etc/network/interfaces according to the link above, bonding starts with system without a problem! Just for reference, my config looks now like this:
===
#bond
auto bond0
iface bond0 inet manual
 bond_slaves none
        bond_mode 4
        bond_miimon 100
        bond_downdelay 200
        bond_updelay 200
        bond_lacp_rate fast

auto eth0
iface eth0 inet manual
 bond-master bond0
        bond_mode 4
        bond_miimon 100
        bond_downdelay 200
        bond_updelay 200
        bond_lacp_rate fast

auto eth1
iface eth1 inet manual
 bond-master bond0
        bond_mode 4
        bond_miimon 100
        bond_downdelay 200
        bond_updelay 200
        bond_lacp_rate fast
===

@Robie, thanks for your help