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Date: Wed, 8 Feb 2012 13:23:29 -0500
From: Gary Palmer <gpalmer@freebsd.org>
To: Steven Hartland <killing@multiplay.co.uk>
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Cc: freebsd-net@FreeBSD.org, Gleb Smirnoff <glebius@FreeBSD.org>
Subject: Re: kern/161899: Repeating RTM_MISS packets causing high CPU load
	for ntpd
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On Wed, Feb 08, 2012 at 01:44:56PM -0000, Steven Hartland wrote:
> ----- Original Message ----- 
> From: "Gleb Smirnoff" <glebius@FreeBSD.org>
> >> Any update on this, would have been nice to see a fix hit before
> >> 9.0. If you need any more information please let me know.
> >
> >AFAIK, this is no longer a problem in 9.0-RELEASE or in HEAD.
> >
> >The cause for this number of misses is absense of a route for
> >IPv4 mapped block in IPv6 routing table.
> >
> >Here it is:
> >
> ># netstat -rn -f inet6 
> >Routing tables
> >
> >Internet6:
> >Destination                       Gateway                       Flags      
> >Netif Expire
> >::/96                             ::1                           UGRS       
> >lo0
> >
> >Some rc.d script installs this prefix in 9.0 and 10.0. If it hasn't
> >been merged to stable/8, then it needs to be found and merged.
> 
> Thanks Gleb!
> 
> Running the following commands does indeed stop this
> route add -inet6 ::ffff:0.0.0.0 -prefixlen 96 ::1 -reject
> route add -inet6 ::0.0.0.0 -prefixlen 96 ::1 -reject
> 
> I found these in /etc/rc.d/network_ipv6 but I can't see why
> these wouldnt be run on a machine that doesn't have an IPv6
> address, they seem to be added correctly on machines that do.

Speculation: the machine(s) which didn't have the routes maybe
didn't have

ipv6_enable="YES"

in /etc/rc.conf?

Gary