Problem with receiving of the UDP multicasting on multiple interfaces in the W2K12 cluster

Question

Hi,
I have my .NET application which receives the UDP multicasting communication. It works fine until it is deployed on a W2K12 cluster. Some multicast groups are still available and some are not in the cluster. The
problem is caused by the cluster which creates a virtual interface for a inter-node communication. When the cluster is on and my app is trying to subscibe to the affected group then IGMP packets are routed to the cluster's
virtual interface where the multicast communication is not available. When the cluster (cluster service) is off all groups are available and IGMP is routed to a right interface.
I also have a different application which is not based on .NET and it receives all multicast groups in any deployment (same W2K12 clustered server). So, I guess that in my app I have to tell to the socket somehow, which local interface should
be used for a particular multicast group. In my app I use code below for a group subscribtion, but I still can't manage routing of IGMP to a right local interface. Can you help me?
As you can see in the code example I try to mapp a group to a local interface using its IP and index using MulticastOption class, but it has no effect. Different interface (cluster's virtual interface) is used for a IGMP
subscribtion. I also tried to bind\set local interface to Any, but without success.
It seems that there is some OS logic which overrides my setup. But, it must be possible to do the socket setup correctlly because non .NET application works fine.
Thanks.
Regards,
Marek
public void Start(string[] args)
//args[0] - multicast group
//args[1] - multicast port
//args[2] - local interface IP
//args[3] - local interface index
UdpClient udp = new UdpClient();
udp.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
udp.Client.Bind(new IPEndPoint(IPAddress.Parse(args[2]), Convert.ToInt32(args[1])));
MulticastOption mcastOption = new MulticastOption(IPAddress.Parse(args[0]));
mcastOption.LocalAddress = IPAddress.Parse(args[2]);
mcastOption.InterfaceIndex = int.Parse(args[3]);
udp.Client.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, mcastOption);
udp.BeginReceive(new AsyncCallback(Receive), udp);

Answer 1

I don’t know if it will help you but I can illustrate my problem on the following prints from netsh and route tools. First print from netsh shows that the affected group 224.0.46.232 is assigned to interface 20. Second print shows
that interface 20 is Microsoft Failover Cluster Virtual Adapter where multicast communication is not available.
When the test app, which works fine, is used than these prints show that group 224.0.46.232 is assigned to interface 19 - Microsoft Network Adapter Multiplexor Driver, where multicast communication is available.
So, the question is how to manage these „prints“ to requested setup in .NET.
Regards,
Marek
C:\Windows\system32>netsh interface ip show joins
Interface 1: Loopback Pseudo-Interface 1
Scope       References  Last  Address
0                    0  Yes   239.255.255.250
Interface 20: Local Area Connection* 12
Scope       References  Last  Address
0                    0  Yes   224.0.0.1
0                    1  Yes   224.0.0.252
0                    1  Yes   224.0.46.232
Interface 19: Public
Scope       References  Last  Address
0                    0  No    224.0.0.1
0                    1  No    224.0.0.252
0                    0  Yes   239.255.255.250
C:\Windows\system32>route print
===========================================================================
Interface List
19...3c d9 2b ef 8a ec ......Microsoft Network Adapter Multiplexor Driver
20...02 91 08 09 1a ae ......Microsoft Failover Cluster Virtual Adapter
  1...........................Software Loopback Interface 1
16...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
21...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3
===========================================================================