About Multicast availability in modern routers...

Dear All:

Hi! I've been developing a pet project of mine for some time, and
early on I decided that for the messaging between computers on the
local network I would use Multicast UDP communication.

I assumed that, by now, this would be supported by most routers (I
believe it became part of the TCP/IP standard back in 1994)... but I
was surprised when I found out that I couldn't use my little program
while at work. The router was a Netopia router from ~2001... upon
further investigation, I found out that Multicast UDP isn't supported
at all in ANY Netopia routers (even to this day).

My attempts to find out the rarity of support for Multicast UDP in
modern routers has failed thus far: most routers don't list whether
they support it or not in their features list, most reviews of
products don't mention Multicast at all, and I've yet to find someone
on the net compiling a list of supporting routers (which I found
especially surprising: someone on the internet can generally be found
who is making a list of pretty much anything imaginable ).

Does anyone know if most routers these days support Multicast UDP (and
thus Netopia routers are a strange anomaly)? I'm especially curious
about if most end-user routers (the type that John Q. Public would buy
at a Best Buy for his home network) still do not support the Multicast
UDP protocols (IGMP I believe it's called? I'm still a relative noob
in the world of network programming).

If you've been fortunate enough to come across a list of routers that
support Multicast UDP (or have made one yourself), I'd also greatly
appreciate being able to view such a list if possible, so that I can
at least have a collection of routers that I can tell users of my
program (likely just myself and friends, for now =) ) to purchase for
the purpose of running the app.

Thanks for any info that can be provided! =)

-Alex