em driver doesn't set multicast ethernet address

[iprebeg at freebsd.org]

On Sat, Jul 11, 2009 at 01:57:49PM +0100, Bruce Simpson wrote:
> Hi,
>
> Thanks for the feedback.
>
> iprebeg at freebsd.org wrote:
>> Well, now, something really interesting happened. I changed default IGMP
>> version via sysctl
>>
>> # sysctl net.inet.igmp.default_version=2
>>
>> but, then I tested it with mtest and generated packets were still IGMPv3
>> Membership reports, but first two of them had proper mcast ethernet
>> address. They generated sent by mtest.
>>   
>
> Sorry, forgot to mention -- this sysctl won't take effect immediately.
> It needs to be set before the interface's driver is loaded and IPv4 is 
> attached to the interface.
>

I placed config in sysctl.conf and rebooted but mcastread still generates IGMPv3
membership report. Am I missing something?

> Do you have any unusual ARP table entries or routing setup? That would be 
> where to look next.
>

Nope. 

> There haven't been any other reports of this issue as far as I know. The 
> IGMP code does not fill out the Ethernet address field -- it leaves it up 
> to ip_output() to do that.
>
> Do you see this with other multicast traffic, or just IGMP reports?
>

I generated multicast traffic with nc and examined packets still have
wrong ether dest address.

So, it seems that no IGMP code is wrong. Can someone please try to
reproduce this with different hardware? I have no other configuration 
but this in VMWare environment.

> thanks,
> BMS
>