[Techtalk] Multicast IP

[Anita Verlorenes]

Hi everyone,

I'm part of a team developing an industrial electronics product.  Our product 
is made of several nodes, connected together via ethernet, which may or may 
not be the customer's corporate ethernet.

We need a method, for the nodes to find each other automatically, without 
having to be explicitly told the addresses of the other nodes in the network.

We were looking at using SSDP (i.e. the node discovery part of UPNP), but I'm 
starting to get a little uneasy with this.

SSDP works by using UDP multicasts over the IP multicast address 
239.255.255.250:1900

Supposedly, according to the SSDP blurb, network administrators setup their 
routers to limit the scope of 239.255.255.250 to some useful scope,  e.g. 
perhaps to the physical premises.

The question is this:   In the real world, does anyone actually use these 
scoped multicast addresses? and do real routers even support them?  

Thanks very much,
Anita.