Re: [magma] Question about IGMP host implementation

"V, Magesh (Magesh)" <> Wed, 12 October 2011 05:23 UTC

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From: "V, Magesh (Magesh)" <>
To: Kunal Shah <>, "" <>
Date: Wed, 12 Oct 2011 10:52:58 +0530
Thread-Topic: Question about IGMP host implementation
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Subject: Re: [magma] Question about IGMP host implementation
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To the best of my knowledge the host does not care about the source-ip of the query for it to respond. I've seen this work always.
OTOH, the igmp router needs to do this check for the reports received because they come from the untrusted side of the n/w.


From: [] On Behalf Of Kunal Shah
Sent: Wednesday, October 12, 2011 6:09 AM
Subject: [magma] Question about IGMP host implementation

Hi all,

Can an IGMPv2 host respond to a general query originated from a subnet other then its own?? RFC 2236 states:

""query received" occurs when the host receives either a valid
     General Membership Query message, or a valid Group-Specific
     Membership Query message.  To be valid, the Query message must be
     at least 8 octets long, and have a correct IGMP checksum.  The
     group address in the IGMP header must either be zero (a General
     Query) or a valid multicast group address (a Group-Specific Query)"

There is no requirement for the source address to be on the same subnet as the host.