[137073] in North American Network Operators' Group
Re: IPv6 addressing for core network
daemon@ATHENA.MIT.EDU (sthaug@nethelp.no)
Wed Feb 9 04:48:10 2011
Date: Wed, 09 Feb 2011 10:48:04 +0100 (CET)
To: iljitsch@muada.com
From: sthaug@nethelp.no
In-Reply-To: <49F6C292-C26D-41E6-953D-F7316D795237@muada.com>
Cc: vikassharmas@gmail.com, nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> Is there a NANOG FAQ we can add this to?
>
> > 1- Use Public Ipv6 with /122 and do not advertise to Internet
> > 2- Use Public Ipv6 with /127 and do not advertise to Internet
>
> The all zeros address is the all routers anycast address so on most non-Cisco routers you can't use it, ruling out /127. The top 128 addresses in any subnet are also reserved anycast addresses although they don't do much in practice. So the longest prefix length you should use is /120 and only use addresses 1 - 127.
A /127 mask is still the best way to handle real point-to-point links
like SDH/SONET today, to avoid the ping-pong problem. Works fine with
Cisco and Juniper, not tried with other vendors.
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
