[Bug 204831] mld_v2 listener report does not report all active groups to the router

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=204831

scheffler at beuth-hochschule.de changed:

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                 CC|                            |scheffler at beuth-hochschule.
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--- Comment #2 from scheffler at beuth-hochschule.de ---
Andrey,

are you sure you are reading the traces correctly?

1.) Maximum Response Code (Delay) is set to 10000 (10s) by the router. Which is
the default value given by RFC3810. 
2.) The Query Intervall (QQIC) is set to the (default) value of 125, but the
unit of this value is seconds.

The router is a Cisco 2811 running IOS 15.1-4.M10, the latest IOS for this
platform supported by Cisco. The router has a basic MC configuration, no timer
values have been changed from the default. The behaviour starts as soon as I
enable 'IPv6 multicast-routing'. I also reproduced the behaviour on a 2901.

Your description of 4-packet burts makes sense - I was wondering about the
500ms delay between packet groups. The 510 groups need 8 packets to report. 
So, the kernel should stop after the second packet group (having reported all
510 groups to the router for this reporting period). However, it does not!
The trace clearly shows that it keeps on reporting the same groups over and
over again until it suddenly starts losing groups from the report.
So to me it looks like 2 bugs:
 1.) Reporting should stop after having reported all 510 groups.
 2.) We should not lose groups from the report which are still active.

In the meantime I found a Linux-Box to run my MC code on and connected it to
the very same router. Here the behaviour is very different. The router sends a
General Query very 125 seconds. Linux reports the 510 groups (using 8 packets)
and stays silent until it receives the next General Query. It also never
reports less than the full 510 groups.
If you think it helps, I can also attach the Linux-trace.

Thomas

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