Does this help any? .SetSocketOption(SocketOptionLevel.Socket,

SocketOptionName.ReuseAddress, 1);

Found at: bytes.com/.../233554-udp-listen-same-port-two-a...

~Lee

I don't know if there are any DBs involved but you could register each node in a table or some other common data source. But perhaps that is what you are trying to avoid with the dependency comment, just thought I would mention it.

I cant figure out if your problem is hard or easy, but just in case its the easy one:

You can not have two applications bound to the same IP address and port.

You can have two applications bound to the same port if they are bound to different IP addresses, so start by giving your PC a second IP address and go from there.

Check out lines 171 in Transports/MulticastUdpEndpoint in MassTransit trunk. The InitializeReceiver method does just what you want.

In fact, there is a unit test with two buses on the same multicast endpoint getting all the business.

        _receiveClient = new UdpClient();


        Socket s = _receiveClient.Client;


        const int optionValue = 1;

        s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, optionValue);


        s.ReceiveBufferSize = 256*1024;

        s.ReceiveTimeout = 2000;

        s.Bind(new IPEndPoint(IPAddress.Any, _uri.Port));


        _receiveClient.JoinMulticastGroup(_groupAddress, 2); // 0 = host, 1 = subnet, <32 = same company

This works with two clients on the same machine joined to the same group address.

Have you considered Zeroconf/Bonjour at all?

I think you'd either need a server that allows peers to register themselves and gives that list to other peers requesting it (and updates when new nodes register) or you'd need a way scan your network. You get an IP address just fire off packets to all other IP addresses at the pre-determined port, if they respond then you know they exist.

You should have a look at WS-Discovery a standard for exactly that.

You can find a sample implementation in C# on:

blogs.msdn.com/.../...y-sample-implementation.aspx

Bo,

It looks like multicast UDP is much simpler

Michael,

That is additional dependency

Chris,

Thanks, exactly what I need.

Lee,

Thanks!

You might want to look at WS-Discovery a little more. For instance it's an inherent facility of WCF in .Net 4.0

weblogs.asp.net/.../...s-discovery-in-wcf-4-0.aspx

Probably a little heavier than you had in mind and they're a Win7 bits...

blogs.msdn.com/.../...ble-with-the-drt-part-1.aspx

blogs.msdn.com/.../...ting-table-in-windows-7.aspx