HELP! VI Server will not work with two network cards

[John Lokanis]

I am in desperate need of a solution today. If you have ever experienced this problem and know a work around, please let let me know how you solved it.

The problem:

I have a test machine with two networks cards in it. One is for connection to the corporate net and one is for connection to a local test net where my DUTs are attached.

I have another machine on the corp net side that is running a LabVIEW app as a server.

The test machine needs to connect as a client to the server app and send commands to control part of the test system.

When I run the client code, I get error 1379: LabVIEW: The user failed a security authentication check.

If I disable the network card in the client that is on the local test net (leaving the corp net connected) then everything works fine.

It appears that if you have 2 network cards, then open application reference gets hosed up and will not connect.

There must be a way to make this work. Thanks for any help anyone can offer in solving this. I have until the end of the day to get this system working.

[Aristos Queue]

A) Have you posted this to DevZone? You're a lot more likely to get an NI AE to help there than here.

B) What version of LV are you using?

[Ton Plomp]

Please correct me if I'm wrong, but I think LabVIEW can only work with 1 (one) Network Interface Card. So creating a bridge between two networks never work with LabVIEW

Ton

[lavezza]

Please correct me if I'm wrong, but I think LabVIEW can only work with 1 (one) Network Interface Card. So creating a bridge between two networks never work with LabVIEW

Ton

Ok, I had a long reply but I lost it when I closed this window by accident. :headbang:

Short comment: I use LabVIEW 7.1.1 on a machine with two network cards to connect a test LAN with a corporate LAN, just like jlokanis. We aren't using VI server, just raw strings over TCP. Maybe the problem is with VI server specifically. Now, our two cards have IP addresses that don't "overlap". In other words, one is a 10.x.x.x number and the other is a 192.168.x.x number. So if I try to connect to 192.168.1.44, there is only one card this will work on. I'm not sure what happens if you are trying to use an address that is valid for both cards. So, I don't pick which card to send stuff on and I'm not sure how LabVIEW decides (or maybe the decision is passed down to Windows?), but it works for us.

Pat

[Rolf Kalbermatter]

Ok, I had a long reply but I lost it when I closed this window by accident. :headbang:

Short comment: I use LabVIEW 7.1.1 on a machine with two network cards to connect a test LAN with a corporate LAN, just like jlokanis. We aren't using VI server, just raw strings over TCP. Maybe the problem is with VI server specifically. Now, our two cards have IP addresses that don't "overlap". In other words, one is a 10.x.x.x number and the other is a 192.168.x.x number. So if I try to connect to 192.168.1.44, there is only one card this will work on. I'm not sure what happens if you are trying to use an address that is valid for both cards. So, I don't pick which card to send stuff on and I'm not sure how LabVIEW decides (or maybe the decision is passed down to Windows?), but it works for us.

Pat

This is really all about TCP IP routing tables and how they are setup. In your case using two exclusive subnet ranges the router has little problems to decide where a packet should go. You can easily influence the most simple routing by setting up according default geateway addresses for each interface so that addresses that do not match one of your subnets are all forwarded to a specific gateway such as a network router (or DSL modem). However once you have two different subnets that both can be default for certain adress ranges, not being the actual subnet itself, you won't be able to get things working right without explicite router tables.

Setting up router tables in corporate network routers is a common task for network administrators but doing so in workstations is seldom done and in the case of Windows usally something to do on the command line. http://support.microsoft.com/kb/140859 might be a good starting point for that.

Rolf Kalbermatter

[LAVA 1.0 Content]

I have a test machine with two networks cards in it. One is for connection to the corporate net and one is for connection to a local test net where my DUTs are attached. I have another machine on the corp net side that is running a LabVIEW app as a server. The test machine needs to connect as a client to the server app and send commands to control part of the test system.

Why not to set up router between the test network and the corporate network. The router can take care of the network address translation and allow only the connections between your client machine and the server machine. You don't need to play with Windows or with LabVIEW, routers can easily take care of these issues.