Wireless – Which address should I use to receive a UDP wireless multicast with iperf

multicastwireless

On computer 1 (192.168.1.3):
I made a route to be sure that my communication pass through my wireless card

sudo route add -net 239.0.0.0 netmask 255.255.255.0 dev wlan2

I launch iperf with the following command :

iperf -c 239.0.0.1 -u -l 1316

On computer 2 (192.168.1.6):
I acknowledge the fact that I am receiveing the traffic on the wireless card with tcpdump.
I launch iperf with the following command:

iperf -s -u -l 1316 -B 239.0.0.1

But nothing comes out from computer 2, do I have to bind it on another address ?

Best Answer

I had this problem using multicast with iperf myself - in my case it was due to the fact that iperf does not let you bind to a multicast source on a specific interface and instead just hardcodes itself to the first interface of the system, meaning that, if the response isn't being received on what is typically eth0, it's useless. From what you say, it sounds like you have this problem too.

So, I wrote a patch that allows you to specify the interface to bind to - you can grab the source from my github repo.

To use it, enter either -O eth123 or --interface eth123 where eth123 is your actual interface name.

I did submit my patch to the project, but, given the inactivity, I suspect the author has either abandoned iperf or is just too busy.

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