Potential DHCP Conflict

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Description

 

Message text:This Device Server has DHCP enabled. New IP-address may work but the use of this new IP will neither be authorized, nor noted by the DHCP server. Do you still want to continue?

 

May appear in:Auto-discovery access mode; Change IP function

 


Details

 

This message is shown when the Change IP function is used while the IP-address of the DS appears to be configured through the DHCP (which means that DHCP (DH) setting is 1 (enabled) and IP-address appears to have been successfully received from the DHCP server i.e. the DS is not in the IP-address not obtained state)*.

 

Technically, the DS will work fine when you assign an IP-address manually (while the network has the DHCP service) as long as you find an unused IP-address**. The problem is that the DHCP server will not know that you have occupied this IP and may assign it to some other device in the future***.

 

Finally, keep in mind that the IP-address you set manually may be changed next time the DS reboots. This is because, when the DHCP (DH) setting is 1 (enabled), the DS negotiates its IP-address with the DHCP server each time it powers up or reboots and the DHCP server may assign a different IP-address at this time. This new IP will be saved into the IP-address (IP) setting thus overwriting the value you may have set.

 

Programmer's info:

 

The DS Manager verifies whether the IP-address of the DS is configured through the DHCP by sending the Echo (X) command and analysing the status of the i flag in the reply. If the flag is set to 'I' then this means that the DHCP is enabled and the DHCP server is actually present on the network.

 

* In other words, the DS Manager does not detect the presence of DHCP server directly but instead relies on the "indirect evidence" from the DS. Unfortunately, this means that the DS Manager won't be able to alert you when the DHCP server is actually present but DHCP (DH) setting is 0 (disabled) on the DS.

 

** This can always be done by PINGing different IPs on the local subnet. No reply means that the IP is probably unused.

 

*** Unless you have specifically banned the DHCP server from using this IP-address (this can usually be done).