Black Box Modular SwitchesInstallation and User Guide (8/99)
LE14XXA-Series Switches are constantly adapting internally to 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 caus “flow control”. This tells the sending devices to temporarily stop sending traffic, which allows 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 LE14XXA--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.
The latency (the time the frame spends in the Switch before it is sent along or forwarded to its destination) of the LE14XXA-Series Switches varies with the port -speed type 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 microseconds plus the packet time at 100Mb.
