Re: A proposal for draft-ietf-6man-rfc4291bis-07

Philip Homburg <> Sat, 04 March 2017 12:58 UTC

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Subject: Re: A proposal for draft-ietf-6man-rfc4291bis-07
From: Philip Homburg <>
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In-reply-to: Your message of "Sat, 4 Mar 2017 13:24:49 +0100 ." <>
Date: Sat, 04 Mar 2017 13:58:31 +0100
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Cc: Alexandre Petrescu <>
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>I agree with the IPv6 facility to have many on-link prefixes.  IPv4 does
>it too these days anyways.
>But I do not agree with mandating there to be multiple on-link prefixes.

Currently at home I have 4 different /64 prefixes as onlink (in addition to
link local). I think all implementations should support that.

>The fe80::/64 is there by default.

Just a note, my stack considers fe80::/10 as onlink. There is no
fe80::/64 in my stack. Of course addr. conf has to treat link local 
special.  But that is already spelled out in the RFC.

>So if I add a 2001:db8:abba:abb*::/60 on some computer it will get two
>different onlink prefixes with different prefix lengths.

So in my implementation adding a /64 creates two different prefix sizes.
It is not clear to me why you would care.

>Two is too much, because it means ND  messages for that /64.  That is
>noise that can create interference.

Onlink prefixes don't generate traffic. It is only when you use them
to configure addresses or when addresses covered by the prefix are
the destination of a packet. But that is exactly the way it should be.

>Ideally, freedom from /64 means that I would only have that /60 prefix
>on the link if that's what I mnaually added.

True, you should be able to consider a /60 onlink. 

>To realize that freedom (avoid ND noise for /64) I have to add the /60
>_and_ delete the /64.

Address configuration should not create onlink prefixs, so I'm not sure
where the /64 comes from.