Pilz PSSnet SHL 8T MRP - Manual (Page 172)

Operation diagnosis
PSSnet SHL - Basic Configuration
Pilz GmbH & Co. KG, Felix- Wankel Str. 2, 73760 Ostfildern
9.8 Detecting IP address conflicts
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9.8 Detecting IP address
conflicts
9.8.1 Description of IP address conflicts
By definition, each IP address may only be assigned once within a subnet-
work. Should two or more devices erroneously share the same IP address
within one subnetwork, this will inevitably lead to malfunctions, including
communication disruptions with devices that have this IP address.In his In-
ternet draft, Stuart Cheshire describes a mechanism that industrial Ethernet
devices can use to detect and eliminate address conflicts (Address Conflict
Detection, ACD).
Mode Meaning
enable Enables active and passive detection.
disable Disables the function
activeDetectionOnly Enables active detection only. After connecting to a network or after an
IP address has been configured, the device immediately checks whether
its IP address already exists within the network.
If the IP address already exists, the device will return to the previous con-
figuration, if possible, and make another attempt after 15
seconds. This
prevents the device from connecting to the network with a duplicate IP
address.
passiveOnly Enables passive detection only. The device listens passively on the net-
work to determine whether its IP address already exists. If it detects a du-
plicate IP address, it will initially defend its address by employing the ACD
mechanism and sending out gratuitous ARPs. If the remote device does
not disconnect from the network, the management interface of the local
device will then disconnect from the network. Every 15
seconds, it will poll
the network to determine if there is still an address conflict. If there isn't,
it will connect back to the network.
Table 21: Possible address conflict operation modes