I'm seeing some serious multicast cross-talk a.k.a "promiscuous traffic" (which is not promiscuous mode, see on wikipedia).

Can anybody confirm this problem ? here's how :
Given the 2 rudimentary programs (attached) : mcsend.c and mcreceive.c (of course you have to compile them: just do gcc -o mcsend mcsend.c and gcc -o mcreceive mcreceive.c ) , open 3 terminal windows A, B and C.
- in terminal A , type: mcreceive 239.192.0.2 21002
- in terminal B, type: mcreceive 239.192.0.3 21004
- in terminal C, type: mcsend 239.192.0.2 21004

Now, in terminal C, type "hello" and enter.

Normally, terminals A and B shouldn't receive anything. However, on at least 2 red-hat (el4 and el5) and 1 centos5 boxes I could verify the "hello" goes through, which proves promiscuous traffic.

Can anybody verify this?

thanks
Guillaume Rava.

Attached Files

	mcreceive.c.txt (3.6 KB, 16 views)
	mcsend.c.txt (2.7 KB, 14 views)

Are they connected through switch?

this is all on one machine. The 2 IP addresses of the example are multicast addresses