Re: [v6ops] ref Hosts dont MLD to join LL groups

Alexandru Petrescu <alexandru.petrescu@gmail.com> Thu, 23 July 2015 12:17 UTC

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To: Ole Troan <otroan@employees.org>
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From: Alexandru Petrescu <alexandru.petrescu@gmail.com>
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Date: Thu, 23 Jul 2015 14:16:43 +0200
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Subject: Re: [v6ops] ref Hosts dont MLD to join LL groups
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If one disallows all MLD joins for all link-scoped IP multicast 
addresses - why does one need IP multicast addresses with link scope?

Why does one need the lino-layer  33::1 address?

If one doesnt need 33::1 then why Ethernet provides it?

I guess what I am trying to say is that it's useless to have multicast 
groups if one can't join them.

Alex

Le 23/07/2015 13:51, Ole Troan a écrit :
> Alexandru,
>
> I’m afraid I couldn’t interpret your message. would someone else be able to translate?
>
> cheers,
> Ole
>
>>>
>>> I do wonder if we should expand that exception to all link-scope
>>> multicast addresses.
>>>
>>
>> I would beg to disagree.
>>
>> If we expand that to all link-scoped groups, may lead to dismantling IPv6 dependence on 33::1 - ff:ff:ff:ff:ff would be sufficient.
>>
>> My oppinion would rather be to modify the MLD RFC to mandate MLD joins for all scopes.
>>
>> Ethernet has primitives for joining the corresponding link-layer groups, and in some cases they are used. Maybe all should use them.
>>
>>> the bridge implementors I speak to tell me that they don’t have
>>> enough state to do MLD snooping for link-local scoped multicast
>>> addresses anyway...
>>
>> This may be dumb from my side, but why dont bridge implementers use link-layer multicast?  They shouldnt implement MLD, and not snoop it. The Hosts should send the necessary link-layer multicast joins (triggered by themselves sending MLD REPORT for these groups) to the bridge addresses.
>>
>> Alex
>>
>>> cheers, Ole
>