Abstract: In an edge router controlling traffic flows using a buffer in a network handling both real-time traffic and data application traffic, a buffer management-based transmission includes receiving a packet from the network and deciding whether the received packet is a choke packet. If the received packet is not the choke packet, then the received packet is classified into a predetermined traffic class. The buffer is divided logically, and a buffer area of the logically divided buffer is assigned to the traffic class into which the received packet is classified. Control of transmission of the received packet includes either dropping the received packet or storing the received packet in the buffer area assigned to the classified traffic class. Accordingly, the present invention can continuously guarantee appropriate bandwidth required for real-time traffic and, at the same time, prevent a situation in which no bandwidth is assigned to data application traffic.