I have a custom made ADC device that is spitting out data by addressed UDP packets.

I have that device plugged into a 4 port switch.

I have one windows embedded standard 7 machine which is the normal recipient of that data. To be able to receive the data (Using LabVIEW) the windows network adapter IPv4 settings must have a static IP address that corresponds to the UDP packet destination.

I would like to add a second windows machine (This one is just regular Win 7 Pro) to simultaneously catch the data, however with all devices connected to the switch, the Win 7 Pro machine recognizes an IP address conflict and will not take the setting for the required static IP address. (The network adaptor settings show that the correct value has been entered but ipconfig shows that it is not actually set.)

Neither windows machine needs to transmit network data, they only need to be able to receive the UDP data from the ADC device.

Is there any way to disable this IP address conflict detection 'feature' of windows networking?

  • 2
    sounds like you need to mirror the switch on a port to your monitoring machine, in which case you don't need two PCs with the same IP. that requires a managed switch however. – Frank Thomas Jun 24 '13 at 16:13

You can't / shouldn't try to use the same IP on the computers, as lot of problems can arise: to begin with, the router will have problems knowing which network MAC is related to the correct (real) IP.

What you could do:

1 - mirror the port , so that the 2nd computer receives all the traffic that comes to the first port, and then put / run the program so that it can capture all traffic that he receives, despite not being addressed to his IP (read about promiscuous mode, for example)

2 - instead of using a router, use a switch, so that all ports will always receive the same packets, and then, again, listen to that in your program.

  • The network device I am using is just a switch that rebroadcasts any packets received on any port to all other connected ports. The problem is with windows not taking the setting for the same IP address because it is polling the network to see if there are others with the same IP. – Stu Jun 24 '13 at 16:58
  • yes, windows won't allow you to do that. Take a look in the "promiscous mode" I said: your network card will receive all the packets anyway. If you just want to receive the packets and store them, you can your wireshark or something like that... do some research about netwaork sniffer – woliveirajr Jun 24 '13 at 17:14

Alternatively you could look into using multicast to solve this problem. If you can program the ADC to send out traffic to a multicast group and then have your two Windows client subscribe to the group. Since you are sending UDP this should work out to your benefit. You will however need a switch that supports IGMP snooping.

Alternatively have your ADC just send packets out to broadcast and then have your Windows hosts listen for that.

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