Eaton Electrical PXES4P Series - Manual (Page 22)

PXES4P Switches Installation and User Guide (10/06)
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likely when traffic is heavy, the result of store-and-forward operation is that more
bandwidth is available for good packets when the traffic load is greatest.
When the Switch detects that its free buffer queue space is low, the Switch sends
industry standard (full-duplex only) PAUSE packets out to the devices sending packets to
cause “flow control”. This tells the sending devices to temporarily stop sending traffic,
which allows a traffic catch-up to occur without dropping packets. Then, normal packet
buffering and processing resumes. This flow-control sequence occurs in a small fraction of
a second and is transparent to an observer. See Section 4.6 for additional details.
Another feature implemented in PXES4P Series Switches is a collision-based
flow-control mechanism (when operating at half-duplex only). When the Switch detects
that its free buffer queue space is low, the Switch prevents more frames from entering by
forcing a collision signal on all receiving half-duplex ports in order to stop incoming traffic.