NETWORK COMMUNICATION APPARATUS AND METHOD OF PREFERENTIAL BAND LIMITATION OF TRANSFER FRAME

摘要

In a network communication apparatus, transfer and discard processing is realized for each transfer frame having a priority, and a band limitation is carried out to prevent the congestion of a transfer destination apparatus. Specifically, a bucket is provided for every priority, and tokens of an amount determined based on the priority are supplemented. Moreover, before a bucket evaluation, one shared bucket is provided. All of the tokens existing in the bucket provided for every priority are transferred to the shared bucket for every constant period. The tokens overflowing beyond a capacity of the shared bucket are discarded. All of the frames are equally evaluated and transferred regardless of the priority of each of the frames, as far as the token exists in the shared bucket. When there is no token in the shared bucket, switching to the preferential band limitation is carried out and each priority bucket is evaluated. The bucket corresponding to the priority of the frame is checked and when the token exists, transfer processing of the frame is carried out. When there is no token, discard processing of the frame is carried out.