Loop Detection - Siemens SCALANCE X-300 Configuration Manual

Configuration using Web Based Management and Command Line Interface
4.5 The Switch menu
4.5.24

Loop Detection

Principle of operation
If the "Loop Detection" function is set for a port, the port sends special test frames, the loop
detection frames. If these frames are sent back to the device, there is a Loop.
If the device receives the sent frames again at another port, a Local Loop has occurred. The
device itself is part of the loop.
If the device receives the sent frames at the same port, a loop has occurred on other
network components, a Remote Loop.
Loops in the network
A loop can, for example, be caused by an incorrect configuration or by plugging in a cable
incorrectly. Mechanical damage to cables can also lead to short-circuits and also cause
loops.
A loop is an error in the network structure that needs to be eliminated. The loop detection
can help to find the errors but does not eliminate them. The loop detection is not suitable for
increasing network availability by deliberately including loops.
Enabling the function
Note
Loop detection is only possible at ports that were not configured as ring ports or standby
ports.
Enabling the function for the device
To enable the "Loop Detection" function generally for the device, select the "Loop Detection
Enabled" option on the "Loop Detection Config" page. On this page, you can make basic
settings that apply to all ports, see section "Loop Detection Configuration".
With this setting, the function is not enabled for all ports. You need to configure the ports
individually.
Enabling ports
For the individual ports, you can set the "Loop Detection" function on the "Loop Detection
Port Configuration" page, see section "Loop Detection Port Configuration".
If there is an error, a port can only be blocked to prevent a loop when it is configured as
"Sender".
256
Configuration Manual, 10/2014, C79000-G8976-C187-22
SCALANCE X-300 / X-400