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

Network load control

7.5 Flow control

7.5 Flow control

7.5.1 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 fig. 32) 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.
Basic Configuration L2P
122
Release 4.2 07/08