IGMP (v3) older version querier timer on OSX

[Brandon Applegate <brandon () burn net>]

First of all - if there is a better place to ask this, let me know.  I simply want to make sure the audience has the 
technical chops to try to answer the question.  So discussions.apple.com / macrumors are out.

I’m trying to figure out how OSX is behaving with regard to downgrading sent IGMP messages in the presence of “older” 
queriers.  I.e. if a query is heard from a router (querier) that is v2, start a timer and only speak (IGMP) in v2 until 
it expires.  From the definitions I’ve found of how to calculate this timer - that should be 260 seconds.  After this 
time, assuming we haven’t heard any further v2 queries - we can start speaking v3 again.  From my testing (using 10.9 
Mavericks and the newest VLC) - this doesn’t happen.  From the network side, I’m using a Cisco 3750 with snooping and 
querier turned on (i.e. not a real mcast router).

If I turn these off and reboot, VLC causes IGMP v3 to be sent.  If I turn querier back on on my switch - OSX drops down 
to IGMP v2.  It just never seems to bounce back to v3.  I think I waited ~ 10 minutes on my last test, and it was still 
v2.

Thanks - and sorry this isn’t about systemd (although I am reading the thread and think it’s a great topic).

--
Brandon Applegate - CCIE 10273
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