> According to the 7.1 of RFC3376 (IGMP V3)
> 7.1. Query Version Distinctions
> The IGMP version of a Membership Query message is determined as
> follows:
> IGMPv1 Query: length = 8 octets AND Max Resp Code field is zero
> IGMPv2 Query: length = 8 octets AND Max Resp Code field is
> non-zero
> IGMPv3 Query: length >= 12 octets
> I have a question about that. For Ethernet the IGMP V2 Query is
> always encapsulated in a 64 bytes packet. da+sa+tpid+ip header+IGMP
> query+padding+fcs=64 bytes,that means after 8 bytes Query fields,there
> are some padding "zeros".For this packet the TOTAL LENGTH filed of IP
> header is 46. So it seems that it's impossible for a snooping
> switch to tell the IGMP QUERY
> version from the IP header length. ...
In my experience, the length in the Ethernet header does not include the
padding bytes but I've found conflicting documentation on the web.
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