Subject: (IPng 6766) Re: Problem with "smart" layer 2 switches

From: [email-masked] (Tim Hartrick)
Date: Thu, 19 Nov 1998 12:11:29 -0800

Brian,

> 
> In talking with our facilities people, I got the impression that these sort
> of IPv4 centric features are becoming more common on layer 2 switches.  So
> this is one more potential problem to look for when deploying v6.  I suppose
> it could even be a barrier to deployment in environments where the local
> network manager has become attached to this sort of feature.
> 

At one time it was suggested that IGMPv6/MLD be used for all IPv6 multicast
addresses.  That is, registrations for the all-nodes, all-routers and
solicited node multicast address all be required to send group report
messages so that boxes of this sort could get a clue about IPv6.  At
a minimum it would seem that a report for the solicited nodes multicast
address would be required in order for these boxes to get a clue.

What makes IPv6 different than other protocols like AppleTalk is that the
solicited nodes multicast address is not well known.  These boxes can have
special rules that deal with well known addresses.  That won't work for
solicited node multicast addresses since they are derived from the link
token.

As an alternative to using MLD I suppose these boxes could use 33:33:ff
prefix of the link-layer address associated with the solicited nodes multicast
as an indicator that it should switch the packet onto all segments.  The
ability to do this type of address specific switching might already exist
in some of these boxes today.

Tim Hartrick
Mentat Inc.
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