User guide

BLACK BOX
®
Series Convenient Switches Installation and User Guide
19
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 Black Box LBH101A-Series Convenient
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 LBH101A-Series Convenient 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. For 10 Mb-to-10 Mb or 10 Mb-to-100Mb or 100Mb-to-10 Mb