Re: [v6ops] Interesting problems with using IPv6

Brian E Carpenter <brian.e.carpenter@gmail.com> Tue, 09 September 2014 07:20 UTC

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Date: Tue, 09 Sep 2014 19:20:53 +1200
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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To: Fernando Gont <fernando@gont.com.ar>
References: <1410082125488.85722@surrey.ac.uk> <540CB702.3000605@gmail.com> <20140908183339.GB98785@ricotta.doit.wisc.edu> <540E26D9.3070907@gmail.com> <540E7DC3.8060408@gont.com.ar>
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Cc: IPv6 Operations <v6ops@ietf.org>, l.wood@surrey.ac.uk
Subject: Re: [v6ops] Interesting problems with using IPv6
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On 09/09/2014 16:10, Fernando Gont wrote:
> On 09/08/2014 06:59 PM, Brian E Carpenter wrote:
>>> See: draft-pashby-magma-simplify-mld-snooping-01
>> OK, but I would also like to understand why we require
>> MLD messages for a Solicited-Node multicast address to
>> set Router Alert.
> 
> Because in theory the multicast router needs to process the MLD message
> to build its forwarding table....

Why, for the Solicited-Node group, which is only meaningful on the link
from which the MLD message arrives?

(NBMA is different of course, but that is not the scenario in the blog.)

  -- or are you arguing that since the
> Dst Addr "includes" the router, the router should process the MLD
> message anyway?

In its role as a node on the same link, participating in ND on that
link, yes. In its role as a forwarding device, surely it should ignore
traffic to the Solicited-Node address? So Router Alert is not
needed. Or am I missing something?

    Brian