UUTs with identical IP addresses

[stephenb2]

I would like to be able to communicate with 2 units under test at the same time. The communication is via telnet, and the UUTs are constrained to have the same IP address, say 192.168.1.10.

 I normally use the internet toolkit telnet VIs. Is there a way, with separate NICs or anything else, to keep the telnet sessions separate? Thanks.

[RavensFan]

Not that  I know of.  Having two devices with the same IP address is a violation of the network.  You are going to have collisions.

Why do they have the same IP address?  What are you REALLY trying to do?

[altenbach]

There is no way this can work.

[stephenb2]

The reason for the duplicate IPs is that the devices have this as their default state used for testing. Perhaps a device in the middle that does some kind of NAT might work? Not a LabVIEW solution per se.

[Dennis_Knutson]

You don't have access to the UUT setup so that you can assign different addresses?

[Hooovahh]

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@Dennis_Knutson wrote:
You don't have access to the UUT setup so that you can assign different addresses?

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This could be product that is at a final functional test, and should be tested using the same settings as it is shipped out with.

Still I suggest changing to unique IPs if you can.  If you can't then you'll need some kind of device in the middle which can intercept the data and effectivly change the IP address.

Or is it possible to test the UUTs one at a time, where you power on one test, power it down then power on the next?  I think some high end switches can have ports turned on and off and this could be another solution.

[Dennis_Knutson]

I've done a lot of production testing of units in parallel and never had a problem with changing back to the default when the test was complete. That was, of course, after validating the devices firmware worked.

[Omar_II]

We use a "Managed Switch" to control which port we are communicating to.

We have ESS chambers with up to 24 UUT all with the same factory default IP address.

You can find 4 port managed switches for under $100. 

[altenbach]

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@Omar_II wrote:

We use a "Managed Switch" to control which port we are communicating to.

We have ESS chambers with up to 24 UUT all with the same factory default IP address.

You can find 4 port managed switches for under $100. 

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But that does not really work with the "parallel" requirement. You can only communicate with one at any given time.

NAT should work with a little bit of effort and some hardware (Plain NAT routers can be had very cheap today). Basically you would have NAT routers with different WAN IPs (all on your factory subnet), but the same LAN subnet. You would define the fixed UUT IP on each LAN subnet as the default server in the router and contact each viat the WAN IP of each router. Turn off the router firewall (if present) and LAN DHCP, etc.

This assumes that the devices are relatively well behaved and are NAT compatible. Telnet should work. If the router runs a telnet server for configuration, you would need to make sure it does not interfere.