Re: [v6ops] Interesting problems with using IPv6

Fernando Gont <fgont@si6networks.com> Wed, 10 September 2014 01:13 UTC

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Date: Tue, 09 Sep 2014 21:40:17 -0300
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To: Brian Haberman <brian@innovationslab.net>, v6ops@ietf.org
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Subject: Re: [v6ops] Interesting problems with using IPv6
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Hi, Brian,

On 09/09/2014 02:09 PM, Brian Haberman wrote:
>> We probably use MLD because "If you use multicast, you use MLD". Truth
>> is that, *unless your switch does MLD snooping* (and hence you *need*
>> MLD, or else your packets will not flow around), you could completely
>> kill MLD, and ND would still work just fine.
> 
> Sure, since NDP is link-local.  The drawback is what happens if your
> network is using RFC 4541 snooping that relies on seeing those MLD
> messages to build forwarding/filtering tables?

Exactly. That's why I said "unless...".



>> Not to mention that there are nodes that default t running MLDv2 *for
>> this* (way overkill, IMO)
> 
> Why is MLDv2 overkill?

If you're just going to use MLD for ND, MLDv2 is unnecessarily complex
-- whole different game if you're using non-link-local multicast, of course.

That said, I seem to recall the node reqs RFC requires MLDv1, rather
than MLDv2?

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492