Multicast Measurements

[materi...@gmail.com]

Greetings!

I am currently attempting to measure latencies by using sockperf to send packets to a multicast address, which is forwarded to three separate systems by a switch.  The setup is as follows:

One multicast sender running the sockperf client.  It is sending traffic to 224.1.1.100
Three recipients of the multicast traffic, each having a sockperf server with address 224.1.1.100.

I'm seeing responses from all three systems, which is what I want.  What I don't understand is why I'm seeing two of the three server's responses coming in as duplicate packets.  To be clear, if I perform a default under-load test, I send 10,000 messages and I get back about 300, 100 messages from each of the multicast clients.  200 of those packets are marked as duplicates.  From reading the posts at

https://code.google.com/p/sockperf/issues/detail?id=11

it seems to me that there was supposed to be an "--enable-extra" parameter available during building that would allow the sockperf client to help clear up what reply is coming from what server, even if they all have the same multicast IP.  I've looked at several versions of sockperf after this topic was closed, and have not found "--enable-extra" anywhere.  I am using version 2.5.241, the currently-released version of sockperf.  I used the following commands to build/compile/install the tool:

./configure --enable-test --enable-doc --enable-tool --enable-debug && make && make install

So, can I actually use sockperf to do a multicast measurement with N number of multicast clients, or is it strictly limited to one multicast server and one multicast client?