Patent ID: 7480247
Filing Date: 2009-01-20
Classification: H04L

Abstract:
1. A packet switch, comprising: a plurality of input side transfer units from which packets are entered; a plurality of output side transfer units from which packets are outputted; a switching unit through which each packet entered from each input side transfer unit is switched to a desired output side transfer unit; a congestion status monitoring unit configured to monitor a congestion status of one of said output side transfer units to which a packet from one of said input side transfer units is destined to reach within the switching unit; a priority level attaching unit configured to attach a priority level to each packet, according to the congestion status of one of said output side transfer units to which the packet from one of said input side transfer units is destined to reach which is monitored by the congestion status monitoring unit; and a packet selection unit configured to select one priority level attached packet that is to be transferred at a higher priority among colliding packets when a packet collision occurs within the switching unit, according to the priority level attached to each colliding packet, wherein the packet with the priority level attached thereto is transferred from an input side transfer unit via the switching unit to an output side transfer unit, the switching unit transfers one colliding packet selected from colliding packets by accounting for the priority level attached to each colliding packet, at higher priority to the output side transfer unit when the packet collision occurs inside the switching unit, the priority level attaching unit is provided at the input side transfer unit, and when a plurality of packets constituting one datagram are to be transferred from the input side transfer unit, the priority level attaching unit sets the priority level of one packet corresponding to a top portion of said one datagram lower than the priority level of other packets corresponding: to subsequent portions of said one datagram, by setting the priority level of the other packets higher than the priority level attached to packets that do not belong to said plurality of packets constituting one datagram.