[153408] in North American Network Operators' Group
Re: IPv6 day and tunnels
daemon@ATHENA.MIT.EDU (Masataka Ohta)
Tue Jun 5 17:45:52 2012
Date: Wed, 06 Jun 2012 06:44:22 +0900
From: Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>
To: "Templin, Fred L" <Fred.L.Templin@boeing.com>,
"nanog@nanog.org" <nanog@nanog.org>
In-Reply-To: <E1829B60731D1740BB7A0626B4FAF0A65D374A89C9@XCH-NW-01V.nw.nos.boeing.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Templin, Fred L wrote:
> General statement for IPv6-in-IPv4 tunneling, yes. But
> inner fragmentation applies equally for *-in-* tunneling.
>
>> Even though you assume tunnel MTU 1500B
>
> What I am after is a tunnel MTU of infinity. 1500 is
> the minimum packet size that MUST get through. 1501+
> packets are admitted into the tunnel unconditionally
> in hopes that they MIGHT get through.
Infinity? You can't carry 65516B in an IPv4 packet.
> My document also allows for outer fragmentation on the
> inner fragments. But, like the RFC4213-derived IPv6
> transition mechanisms treats outer fragmentation as
> an anomalous condition to be avoided if possible - not
> a steady state operational approach. See Section 3.2
> of RFC4213.
Instead, see the last two lines in second last slide of:
http://meetings.apnic.net/__data/assets/file/0018/38214/pathMTU.pdf
It is a common condition.
Masataka Ohta
