Question DLL in Win7 Embeded and Win7 Pro

[stulish]

Hi not sure if this is the correct forum thread for this, but i have created a DLL using Vb.net and VS2012 and it works great on my development PC which is Win 7 Professional. The DLL receives Packets over multicast UDP and then reassembles the data and sends acknowledgements back over the network.

This all worked great while developing, i went and installed the app on the system it is to be used on which is a windows 7 embedded system but nothing works, its as it if cant see the data.

I used wireshark to ensure the packets hadn't been stopped by security policies or the firewall and i could see the data arriving in wireshark.

Does anyone have any idea where to look or what to test for, i think there is some driver somewhere that isn't the same in embedded compared to professional, also has anyone else experienced anything like this??


Thanks

Stu

 

[Herman]

Windows Embedded Standard only has .NET 3.5 support, so try making sure you are targetting that framework just in case.

 

[stulish]

Thanks Herman,

I will give that a go i used .NET 4.0 but there is nothing groundbreaking in the code so it should recompile easily enough

Stu

 

[stulish]

Hi Herman,

Just to let you know, i recompiled at .NET 3.5 and it worked straight away, so thanks for you help i could have seen myself spending hours pulling my hair out

Stu

 

[stulish]

I spoke too soon,

The problem is back so the compiling with dot net 3.5 wasn't the problem.

The WSE7 system i am using the DLL in has 4 NIC's fitted and having looked on the net this can cause problems, i have pasted the code below that sets up the socket:

 [COLOR=#a31515][/COLOR]
        _rxEndpoint = [COLOR=blue]New[/COLOR] [COLOR=#2b91af]IPEndPoint[/COLOR](_NICIPaddress, _MulticastPort)
        _rx.Client.SetSocketOption([COLOR=#2b91af]SocketOptionLevel[/COLOR].Socket, [COLOR=#2b91af]SocketOptionName[/COLOR].ReuseAddress, [COLOR=blue]True[/COLOR])
        _rx.ExclusiveAddressUse = [COLOR=blue]False[/COLOR]
        _rx.Client.ReceiveTimeout = 15000
        _rx.Ttl = _tTl
        _rx.Client.Bind(_rxEndpoint)
        _rx.JoinMulticastGroup(_MulticastIP)
        ListenThread.Start()
        LastGoodImageSave = [COLOR=#2b91af]DateTime[/COLOR].Now
        LastImageSave = [COLOR=#2b91af]DateTime[/COLOR].Now
        Timer_SaveImageCheck.Interval = 1000
        Timer_SaveImageCheck.Enabled = [COLOR=blue]True[/COLOR]
        _isCapturing = [COLOR=blue]True[/COLOR]

I read on the net the following:

from: How do I re-open the Visual Studio Immediate Window? - Stack Overflow

Mike G Reply:
I had the same issue on a windows failover cluster... Multiple nics....
I ended up opening a case with Micorsoft as I thought it was an OS issue.
It wasn't.
You need to specify the IP of the interface you whant to use to create a IPEndpoint. THen use that endpoint when creating the socket instead of IPAddress.any
That solved the problem for me.
Hope it helps even if it is late.

Dave's Reply:
Mike G is correct. One of the constructors for the UDPClient class takes an IPEndPoint as an argument. If the IPEndPoint is set to the IP address of a local interface, then that is the interface that the UDPClient and underlying socket will use so yes, you can have two UDP clients bound to the same port on a a machine as long as they are on seperate local IP interfaces (i.e. multi-homed or multi-NIC).

so as you see from the code above i set the IPEndPoint to the NIC Address (_NICIPaddress), in my case the NIC IP address is 172.16.0.25, rather than IPAddress.Any

The network cards IP addresses are set as below:

Cable Ident	Network Connection	IP Address
1	To Switch 1	172.16.0.25
2	To Switch 2	192.168.2.19
4	Data Download	192.168.0.4
3	Expansion	192.168.1.4

The PC sending the UDP Data has an IP of 172.16.0.42 and this is connected via network Switch 1 to the NIC with IP 172.16.0.25.

Hopefully what i have done makes sense, if i have missed any infor that would be useful let me know.

Finally i found on the WSE7 system if i disconnect the network cables from all other NIC then the app starts recieving the packets ok, and then if i plug the network cables back in the app keeps receiveing the packets, until i restart the system.

My questions are as follows:

Has anyone else experienced something like this?

Does anyone know a way to get it working?

And have i implemented it correctly?

Thanks for any advice/help.

Stu

 

[stulish]

Fixed At Last - I hope

I think i have cracked it and it is really simple, i just added the NIC IP address to the JoinMulticastGroup and it seems to work everytime now:

        _rx.JoinMulticastGroup(_MulticastIP,NICIPaddress)

 

[JohnH]

I think i have cracked it and it is really simple, i just added the NIC IP address to the JoinMulticastGroup and it seems to work everytime now:

        _rx.JoinMulticastGroup(_MulticastIP,NICIPaddress)

Good find, it is not documented for JoinMulticastGroup method, but it is at a lower level code, although it is a clue that there exist an overload of the method has a local ip parameter.
I had a look at source code for that method and found that it does Client.SetSocketOption with AddMembership and a MulticastOption with only the multicast ip (local address is here set to IPAddress.Any). And here you can find the "small print": MulticastOption Constructor (IPAddress) (System.Net.Sockets)

For machines with multiple network cards, do not use this constructor. Use the constructor that takes a group and a local IP address.

So when you use the JoinMulticastGroup with both group ip and local ip the correct MulticastOption is also used.