[libvirt-users] Need information

Hi, Referring to the link http://wiki.libvirt.org/page/VirtualNetworking, the scenario described for the routed mode, explains that "Host has public IP and virtual machines have static public IPs. But one can't use bridged networking, since provider accept only packets from the MAC address of the host" Can someone explain to me why doesn't the switch accept the packets from the guest vms' mac addresses also since they have public IPs in the bridged mode ? Thanks Kumar