Flow Control; Description Of Flow Control - Hirschmann RS20 User Manual

Network Load Control

8.5 Flow Control

8.5 Flow Control
8.5.1

Description of Flow Control

Flow control is a mechanism which acts as an overload protection for the
device. During periods of heavy traffic, it holds off additional traffic from the
network.
The example (see figure 31) shows a graphic illustration of how the flow
control works. Workstations 1, 2 and 3 want to simultaneously transmit a
large amount of data to Workstation 4. The combined bandwidth of
Workstations 1, 2 and 3 to the device is larger than the bandwidth of
Workstation 4 to the device. This leads to an overflow of the send queue of
port 4. The funnel on the left symbolizes this status.
If the flow control function at ports 1, 2 and 3 of the device is turned on, the
device reacts before the funnel overflows. Ports 1, 2 and 3 send a message
to the connected devices that no data can be received at present.
UM BasicConfig L2E
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Release 8.0 05/2013