Patent ID: 7908390
Filing Date: 2011-03-15
Classification: H04L,H04Q

Abstract:
1. A packet forwarding apparatus for transmitting packets having: an interface unit sending and receiving packets, a packet switch outputting a received packet to the interface unit as a destination of the received packet, and a traffic shaper controlling timing of packet transmission, wherein the traffic shaper comprises: a bandwidth control unit controlling a packet transmission bandwidth, a packet buffer for temporarily storing the received packet, and a request selecting unit determining the received packet to be read out from the packet buffer, wherein the bandwidth control unit comprises: a first timing generator that makes a first determination judging whether the received packet can be read out from the packet buffer with a bandwidth less than a minimum guaranteed bandwidth or not by using a part of a token bucket algorithm, and a second timing generator that makes a second determination judging whether the received packet can be read out from the packet buffer with a bandwidth less than a maximum allowable bandwidth or not by using a part of a leaky bucket algorithm, wherein the part of the token bucket algorithm judges that the received packet can be read out from the packet buffer with a bandwidth less than the minimum guaranteed bandwidth when a quantity of tokens held in a token bucket is positive, and the part of the leaky bucket algorithm judges that the packet can be read out from the packet buffer with a bandwidth less than the maximum allowable bandwidth when a quantity of tokens held in a leaky bucket is zero, wherein the request selecting unit determines that the received packet can be read out from the packet buffer, when the first timing generator judges based upon the part of token bucket algorithm that the packet can be read out from the packet buffer with a bandwidth less than the minimum guaranteed bandwidth and concurrently the second timing generator also judges based upon the part of the leaky bucket algorithm that the packet can be read out from the packet buffer with a bandwidth exceeding the maximum allowable bandwidth, wherein the request selecting unit determines that the received packet can be read out from the packet buffer when, the first timing generator also judges based upon the part of the token bucket algorithm that the received packet can be read out from the packet buffer with a bandwidth exceeding the minimum guaranteed bandwidth and concurrently the second timing generator judges based upon the part of the leaky bucket algorithm that the received packet can be read out from the packet buffer with a bandwidth less than the maximum allowable bandwidth, wherein the request selecting unit, in response to determining that the received packet can be read out from the packet buffer based upon the first determination made by the first timing generator and the second determination made by the second timing generator, sends a transmit approval signal to the packet switch that includes an indication of the received packet, wherein the packet switch, in response to receiving the transmit approval signal, reads the received packet from the packet buffer according to the indication included within the transmit approval signal, and wherein the interface sends the received packet upon the received packet being read from the packet buffer.