> -----Original Message----- > From: Masataka Ohta [mailto:mo...@necom830.hpcl.titech.ac.jp] > Sent: Tuesday, June 05, 2012 2:44 PM > To: Templin, Fred L; nanog@nanog.org > Subject: Re: IPv6 day and tunnels > > 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.
I should qualify that by saying: 1) For tunnels over IPv4, let infinity equal (2^16 - 1) minus the length of the encapsulation headers 2) For tunnels over IPv6, let infinity equal (2^32 - 1) minus the length of the encapsulation headers > > 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. Are you interested in only supporting tinygrams? IMHO, go big or go home! Fred fred.l.temp...@boeing.com > Masataka Ohta