[c-nsp] Multicast Issue

[Antonio Querubin]

On Thu, 27 Apr 2006, John Neiberger wrote:

> The client begins talking to the server via TCP, so it already
> obviously knows the server's IP address. After it's been talking to the
> server for a few seconds (a couple hundred packets) the client sends a
> single multicast packet to 224.0.1.55. This is some sort of server
> location mechanism. But it shouldn't be necessary because the client
> obviously already knows the IP address of the server. To make this even
> more colossally dumb, the IP address of the server is IN THE DATA
> PORTION OF THE MULTICAST PACKET! If the client does not receive a
> unicast response to this multicast packet, the client can't connect, at
> least from the user's perspective. Really bad design because that means
> that the server doesn't use IGMP to join the group, which means it has
> to be on the same LAN as all of the clients. I'm just trying to find a
> way to make it work for now until we can talk to the developers of the
> application.

Seems that the root of the problem is that the server isn't joining the 
group so the fix should be applied there.  Couldn't you just write a small 
routine that runs concurrently on the server and joins the group?  And 
then let the router handle multicast normally.