Subject: [SAM] detect the presence of an IGMPv3 querier

From: Sebastian Wölke <[email-masked]>
Date: Fri, 20 May 2011 13:36:16 +0200

Hi all,

I'm working on a system software that automatically detects the presence
of a multicast querier in the current subnet based on passively
monitoring Linux kernel states.

This works fine for IPv6/MLD by looking into the /proc/net/SNMP6 table.
For IPv4/IGMP, the SNMP approach does not work. I can detect an IGMPv2
querier by monitoring 'Timer' in the /proc/net/igmp table: this counts
down the [Unsolicited Report Interval]. However, this does not exist for
IGMPv3, as reports are not suppressed.

My question is about IGMPv3. Does anybody know how to detect the
presence of an IGMPv3 querier based on the kernel states of a multicast
client?

Thanks for your support,

Sebastian

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From: Stig Venaas <[email-masked]>
Date: Fri, 20 May 2011 10:45:36 -0700

> presence of an IGMPv3 querier based on the kernel states of a multicast

If you look at "/proc/net/igmp" it should give you the querier version.
I see e.g.:

Idx     Device    : Count Querier       Group    Users Timer    Reporter
1       lo        :     0      V3
                                 010000E0     1 0:00000000               0
2       eth0      :     3      V3
                                 010000E0     1 0:00000000               0

Doesn't this work?

Stig

>
> Thanks for your support,
>
> Sebastian
> _______________________________________________
> SAM mailing list
> [email-masked]
> http://www.irtf.org/mailman/listinfo/sam

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From: Sebastian Wölke <[email-masked]>
Date: Mon, 23 May 2011 09:47:59 +0200

This dosen't work. The default Querier version is V3. If no Querier
present the version is set to V3.

Sebastian

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From: "Thomas C. Schmidt" <[email-masked]>
Date: Sun, 29 May 2011 18:12:02 +0200

Hi Stig et al.,

do you (or anybody else) have an idea where to look for traces of IGMPv3 
queriers in the linux kernel tables otherwise?

Thanks,

Thomas

On 23.05.2011 09:47, Sebastian Wölke wrote:
> 2011/5/20 Stig Venaas<[email-masked]>:

-- 

Prof. Dr. Thomas C. Schmidt
° Hamburg University of Applied Sciences                   Berliner Tor 7 °
° Dept. Informatik, Internet Technologies Group    20099 Hamburg, Germany °
° http://www.haw-hamburg.de/inet                   Fon: +49-40-42875-8452 °
° http://www.informatik.haw-hamburg.de/~schmidt    Fax: +49-40-42875-8409 °