GarrettCom 4K16 - Manual (Page 16)

Magnum 4K16 Switches Installation and User Guide (12/05)
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provide maximum network performance with the least dropped packets.
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 Magnum 4K16 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.
The latency (the time the frame spends in the Switch before it is sent along or
forwarded to its destination) of the 4K16 Switches varies with the port-speed types, and
the length of the frame is a variable here as it is with all store-and-forward switches. The
4K16 Switch’s latency is 5 microseconds plus the packet time at 100Mb. See Section 1.1
Specifications.