nanog mailing list archives

Re: IPv6 and multicast listener discovery


From: "Dale W. Carder" <dwcarder () es net>
Date: Mon, 7 Jun 2021 11:34:07 -0500


Are your links or hosts limited in some way or broadcast domains
of some unreasonable size?  Most of the competent switching or 
managed wireless products will snoop or otherwise handle this 
overhead in a sane manner.  Otherwise this at best would seem to 
be an over-optimization.

From my days on a giant campus network the current pps rate of MLD
chatter was much lower than the IPX/SAP broadcasts we had from 
20-25 yrs earlier.

Dale

Thus spake William Herrin (bill () herrin us) on Fri, Jun 04, 2021 at 02:01:19PM -0700:
Howdy,

Question for those more versed in IPv6 than I: Is there any harm from
dropping ICMPv6 multicast listener discovery reports in a network
which does NOT use any multicast routing (i.e. only uses multicast
which stays within the local link). I see a LOT of idle node chatter
in the form of these reports which, of course, flood every station
since they are themselves multicast. As far as I can tell they are
used only to tell a multicast router whether to repeat a particular
set of multicast packets to the instant link. Which in my network is
-never- because there are no routed multicast packets to be repeated.

Regards,
Bill Herrin

-- 
William Herrin
bill () herrin us
https://bill.herrin.us/


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