Patent ID: 8780719

Claim:
A packet relay apparatus relaying packets exchanged between communication apparatuses with a connection established, the packet relay apparatus comprising: a buffer to store a packet selected from among arrival packets so that a transfer of the selected packet is to be suspended; and a congestion controller to monitor, after the storage of the selected packet on the buffer, at least one other packet passing through the packet relay apparatus, and causing the selected packet, stored on the buffer, to be transmitted at a timing responsive to a passage status of the at least one other packet having a same connection as the connection of the selected packet stored on the buffer, wherein the congestion controller includes a counter counting a number of the at least one other packet having the same connection that arrived after and has passed through the packet relay apparatus while the selected packet is suspended and stored in the buffer, and the congestion controller determines the timing based on the number of the at least one other packet having the same connection passing through the packet relay apparatus, wherein the congestion controller includes a connection manager to determine when congestion occurs for a connection, and the counter receives an instruction from the connection manager when congestion occurs, counts the number of the at least one other packet having the same connection passing through the packet relay apparatus, and causes transmission of the packet stored on the buffer at a timing at which the counter equals a specific number; wherein the congestion controller estimates a number of response packets a communication apparatus operating as a destination of the packet stored on the buffer has transmitted to a communication apparatus operating as a source, based on the number of the at least one other packet of the same connection and a time elapse from a previous detection of a packet of the same connection, and determines the timing for transmission of the packet stored on the buffer based on the estimated number of response packets.