multicast issues

[Hans-Peter Jansen]

Hi,

after reading the multicast howto again, googling around, and trying to 
estimate the current state of affairs with multicast, I'm still confused 
how the pieces work together. 

The only reliable group address to get my stuff to work with seems 
224.0.0.1, which should be avoided, AFAICS.

The howto states, that it's necessary to add a route similar to:
route add -net 224.0.0.0/4 dev eth0
but nevertheless, the attached test program works on some systems (Intel 
e1000 || NVIDIA MCP55 NIC, Linux 2.6.24.3, openSUSE 10.2), or it does not 
(NVIDIA MCP51 NIC, rest as above), independent from setting such a route.

I also experimented with:
ip route add multicast 224.0.0.0/4 dev eth0
which makes the output of ip route look different, but not the behavior.

Could somebody enlight me, what's the culprit here? Is multicasting still 
such a mess? Is my test program silly?

Puzzled,
Pete

Attachment: mctest.py
Description: application/python