Playing with Multicast

Just an addendum to my previous entry - a few useful tricks I picked up whilst setting up a lab for playing with multicast.

Generating lots of multicast traffic

A dead quick and easy way of producing multicast traffic is to use iperf - normally a bandwidth-testing tool. It will happily send to multicast addresses, just give it a multicast IP as a destination. Using UDP we can send traffic aimlessly without worrying whether there is an iperf server on the other end. Use the syntax below!

iperf -u -p 1234 -c 224.1.1.1 -b 50M -t 86400

I actually used multiple instances simultaneously, to produce a few variable sized multicast streams to different multicast IPs.

Receiving multicast traffic

Also easy, using socat, a somewhat more versatile version of netcat. Syntax below!

socat STDIO UDP4-RECV:1234,ip-add-membership=224.1.1.1:eth0 > /dev/null

Obviously you may want to send the traffic somewhere other than /dev/null - but if you've generated it from iperf with the above syntax, there will be quite a lot of it!

Have fun playing with multicast in your lab!