Patent ID: 7313144
Filing Date: 2007-12-25
Classification: H04L

Abstract:
1. A frame transmission device for causing supervisory frames to enter subscriber traffic to be transmitted along with subscriber frames, comprising: a shared buffer having subscriber queues for storing subscriber frames and a supervisory queue for storing supervisory frames; a queue length management section for managing a supervisory queue length which is a length of the supervisory queue, and subscriber queue lengths which are lengths of the respective subscriber queues; a supervisory token computing section capable of setting a minimum bandwidth for transmitting the supervisory frames and accumulating supervisory tokens for giving the supervisory frames permission to transmit within the set minimum bandwidth, said supervisory token computing section reducing the supervisory tokens in accordance with a result of queue read judgment; subscriber token computing sections associated with the respective subscriber queues and capable of optionally setting transmission bandwidths for the respective subscriber queues within a transmission bandwidth equal to a best-effort transmission bandwidth of the subscriber traffic minus the minimum bandwidth for the supervisory frames, said subscriber token computing sections accumulating subscriber tokens for giving the subscriber frames permission to transmit within the respective set transmission bandwidths and reducing the subscriber tokens in accordance with the queue read judgment result; a best-effort token computing section capable of setting the best-effort transmission bandwidth of the subscriber traffic and accumulating best-effort tokens for giving the supervisory frames or the subscriber frames permission to transmit by using an extra bandwidth and within the set best-effort transmission bandwidth, said best-effort token computing section reducing the best-effort tokens in accordance with the queue read judgment result; and a queue read control section for comparing the queue lengths with respective token storage amounts as the queue read judgment when reading the frames from the respective queues, wherein when the supervisory queue length is smaller than or equal to the supervisory token storage amount, said queue read control section permits the supervisory frames to transmit within the minimum bandwidth and reads and outputs supervisory frames corresponding to the supervisory queue length from the supervisory queue, when the subscriber queue length is smaller than or equal to the corresponding subscriber token storage amount, said queue read control section permits the subscriber frames to transmit within the transmission bandwidth set with respect to the corresponding subscriber queue and reads and outputs subscriber frames corresponding to the subscriber queue length from the corresponding subscriber queue, when the supervisory queue length is greater than the supervisory token storage amount and at the same time a remaining supervisory queue length in the supervisory queue obtained by subtracting the supervisory token storage amount from the supervisory queue length is smaller than or equal to the best-effort token storage amount, said queue read control section permits the supervisory frames to transmit by using the extra bandwidth and reads and outputs supervisory frames corresponding to the remaining supervisory queue length from the supervisory queue, and when the subscriber queue length is greater than the corresponding subscriber token storage amount and at the same time a remaining subscriber queue length in the corresponding subscriber queue obtained by subtracting the subscriber token storage amount from the subscriber queue length is smaller than or equal to the best-effort token storage amount, said queue read control section permits the subscriber frames to transmit by using the extra bandwidth and reads and outputs subscriber frames corresponding to the remaining subscriber queue length from the corresponding subscriber queue.