BLACK BOX→ Power Over Ethernet Switch(PoE) Installation and User Guide
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 Black Box LP004A-Series Power over Ethernet (PoE) Switch 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 LP004A-Series Power over Ethernet (PoE) Switch 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. For 10 Mb-to-10 Mb or 10 Mb-to-100Mb or 100Mb-to-10 Mb forwarding, the latency is 15 microseconds plus the packet time at 10 Mb. For 100Mb- to-100Mb forwarding, the latency is 5 microseconds plus the packet time at 100Mb.
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