Packet data transmission

摘要

A multi-port data communication device e.g. for an Ethernet system includes a common central memory 5 through which all data packets must pass. Packet data is written to and read from the common memory space 5 in bursts in response to receive write requests and transmit read requests. A transmit read request for a first burst of data in a packet has in a central arbiter 7 a relatively low priority and transmit read requests for a second and any subsequent burst of data in a packet have in the central arbiter 7 a relatively high priority. Preferably the receive write requests have in said central arbiter a priority intermediate said relatively low priority and said relatively high priority. The priority system reduces the likelihood of underrun and overrun particularly when the burst size is generally smaller than the packet size.