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Old 12-19-2009, 02:35 PM   #1
guillaumerava
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Exclamation multicast cross-talk issue - anybody else confirm ?


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
File Type: txt mcreceive.c.txt (3.6 KB, 1 views)
File Type: txt mcsend.c.txt (2.7 KB, 2 views)
 
Old 12-19-2009, 02:58 PM   #2
nimnull22
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Are they connected through switch?
 
Old 12-20-2009, 09:22 PM   #3
guillaumerava
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this is all on one machine. The 2 IP addresses of the example are multicast addresses
 
  


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