When a network apparatus of this invention receives an IEEE 802.3ad link application control packet from a subscriber line with a VPWS function, it processes the packet in a control unit without relaying the packet by VPWS. More specifically, the network apparatus receives an IEEE802.3ad link aggregation control packet along with receiving an IEEE802.3x flow control packet. The network apparatus transmits a link aggregation control packet. The network apparatus also relays other layer 2 control protocol packets without receiving them, and does not transmit the other layer 2 control protocol packets.