Bandwidth monitoring device

A bandwidth monitoring device for monitoring a packet bandwidth, comprising:

• a counter residual quantity value determining portion which determines a current counter residual quantity value which represents a residual value of a packet length counter value by adding up inputted packet lengths and subtracting outputted packet lengths immediately prior to input of a next input packet;
• and
• a monitoring results determining portion which sets determination criteria, and determines in accordance with the determination criteria whether input packets violate or comply with a monitored bandwidth;
• wherein the determination criteria include a determination criterion, based on the counter residual quantity value from said counter residual quantity value determining portion, that all input packets are in compliance with the monitored bandwidth when the counter residual quantity value is equal to or less than a first threshold value;
• wherein the determination criteria include a determination criterion such that a drop probability, by which a determination is made that input packets violate the monitored bandwidth when the counter residual quantity value exceeds the first threshold value, becomes greater pursuant to increases in the counter residual quantity value;
• and
• wherein the determination criteria include a determination criterion that all input packets violate the monitored bandwidth when the counter residual quantity value exceeds a second threshold value which is greater than the first threshold value,
• wherein said monitoring results determining portion determines a rate of change of a counter residual quantity value from a preceding counter residual quantity value and a preceding time corresponding to the preceding counter residual quantity value, and the current counter residual quantity value determined by said counter residual quantity value determining portion, and a current time corresponding to the current counter residual quantity value, to determine a change rate of the drop probability relative to the counter residual quantity value in accordance with the determined rate of change of the counter residual quantity value, and to determine, based on the current counter residual quantity value and a random number value, whether or not input packets will be dropped in accordance with said determination criteria by virtue of an updated drop probability which is updated according to the change rate of the drop probability.

A bandwidth monitoring device for monitoring a bandwidth of either fixed-length or variable-length packets, the bandwidth monitoring device comprising:

• a counter residual quantity value determining portion which determines a current counter residual quantity value which represents a residual value of a packet length counter value by adding up inputted packet lengths and subtracting outputted packet lengths immediately prior to input of a next input packet;
• and
• a monitoring results determining portion which sets determination criteria, and to determine in accordance with the determination criteria whether input packets violate or comply with a monitored bandwidth;
• wherein the determination criteria include a determination criterion, based on an added value representing a sum of the counter residual quantity value from said counter residual quantity value determining portion and a packet length of the next input packet, that all input packets are in compliance with the monitored bandwidth when the added value is equal to or less than a first threshold value;
• and
• wherein the determination criteria include a determination criterion such that a drop probability, by which a determination is made that input packets violate the monitored bandwidth when the added value exceeds the first threshold value, becomes greater pursuant to increases in the added value,
• wherein said monitoring results determining portion determines a rate of change of a counter residual quantity value from a past counter residual quantity value and a past time corresponding to the past counter residual quantity value, and a current counter residual quantity value determined by said counter residual quantity determining portion and a current time corresponding to the current counter residual quantity value, to determine a change rate of a drop probability relative to the counter residual quantity value in accordance with the determined rate of change, and to determine, with respect to the current counter residual quantity value, whether input packets violate or comply with the monitored bandwidth in accordance with said determination criteria by virtue of an updated drop probability which is updated according to the change rate of the drop probability.

A bandwidth monitoring device, comprising:

• a packet receiving circuit which receives packets;
• a counter which counts a total packet length by adding up inputted packet lengths including a packet length of a next input packet and subtracting outputted packet lengths to produce a counted value;
• a timer which times a packet receiving time;
• a memory which stores a number of packet receiving times and a number of counted values counted by said counter which correspond to the packet receiving times, respectively;
• a counter rate-of-change calculating portion which calculates a change rate by a first counted value corresponding to an oldest packet receiving time stored in said memory representing an oldest time at which a packet was received and a second counted value corresponding to a latest packet receiving time stored in said memory representing a latest time at which a packet was received;
• and
• a determining portion which decides whether the next input packet will be discarded based on a probability computed by said change rate and the counted value counted by said counter when said packet receiving circuit receives the next input packet.