NETWORK SWITCH HAVING VIRTUAL INPUT QUEUES FOR FLOW CONTROL

A network switching device for transferring data among n channels includes n receive circuits and n ingress modules. The receive circuits receive frames from n channels. The ingress modules include a memory circuit that stores each frame in buffers. The buffers store bytes of data. A destination resolution circuit selects a destination channel for each of the frames. A forwarding module enqueues each buffer to the respective destination channel. Egress modules transmit data in the buffers enqueued to the n channels. Each of the n counters stores a count for a respective n channel. The counters are incremented when a respective ingress module enqueues a buffer to a destination channel. The counters are decremented after the data stored in a buffer is transmitted to the n channels. The egress modules exercise flow control on a respective channel when a respective count is greater than a pause threshold.