50 computers, computer room, computer room with a huawei s5320-52.0003 billion access layer switches, switch port (5700), huawei is part is ready to exchange vlan) under layer 3 switches connect PC to Internet access was not on the net, the network card exclamation mark, restart the network card is also began to it is not can surf the Internet, computer room and so are other machines, on the 5320 linked to hang a layer 2 switch after 5700, and then pick up from the 5320 PC network is normal. (this is MB network), help masters help me,