Re: [v6ops] PMTUD issue discussion

"Templin, Fred L" <Fred.L.Templin@boeing.com> Fri, 05 September 2014 14:48 UTC

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From: "Templin, Fred L" <Fred.L.Templin@boeing.com>
To: Joe Touch <touch@isi.edu>, "Fred Baker (fred)" <fred@cisco.com>, "Fernando Gont" <fgont@si6networks.com>
Thread-Topic: [v6ops] PMTUD issue discussion
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Date: Fri, 5 Sep 2014 14:48:06 +0000
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References: <0D370E74-688B-4EB3-A691-309A03AF20BA@cisco.com> <53FBA174.2040302@isi.edu> <53FBA6E1.90905@bogus.com> <CAPi140PMeM9omtm11+NHa2ywUfof_tE7HknKExtoEb32mm7L_w@mail.gmail.com> <71D0D5E8-80E9-430B-8ED4-16C1F99082CC@cisco.com> <54020ECC.4000000@globis.net> <CAEmG1=redpYUnv9R-uf+cJ4e+iPCf6zMHzVxeKNMGjcC=BjR+Q@mail.gmail.com> <5402C26A.8060304@globis.net> <540626F6.1020103@scea.com> <60533790-9A16-44C8-8239-89AE2C6BD783@cisco.com> <5408F6C6.3030103@gont.com.ar> <080303C1-D09F-4987-B114-F0F5C8B44863@cisco.com> <5409080E.7000200@si6networks.com> <9F0F552B-B465-40C4-8206-82A289294787@cisco.com> <5409C1D2.60604@isi.edu>
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Cc: "v6ops@ietf.org" <v6ops@ietf.org>, Tom Perrine <tperrine@scea.com>, Fernando Gont <fernando@gont.com.ar>
Subject: Re: [v6ops] PMTUD issue discussion
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> -----Original Message-----
> From: v6ops [mailto:v6ops-bounces@ietf.org] On Behalf Of Joe Touch
> Sent: Friday, September 05, 2014 7:00 AM
> To: Fred Baker (fred); Fernando Gont
> Cc: v6ops@ietf.org; Tom Perrine; Fernando Gont
> Subject: Re: [v6ops] PMTUD issue discussion
> 
> 
> 
> On 9/4/2014 5:58 PM, Fred Baker (fred) wrote:
> >
> > On Sep 5, 2014, at 10:47 AM, Fernando Gont <fgont@si6networks.com> wrote:
> >
> >> On 09/04/2014 09:24 PM, Fred Baker (fred) wrote:
> >>>
> >>> On Sep 5, 2014, at 9:33 AM, Fernando Gont <fernando@gont.com.ar>
> >>> wrote:
> >>>
> >>>> What happens when/if such lins employ v6 (whether they really
> >>>> offer a "virtual" MTU >=1280).. I just don't know.
> >>>
> >>> 802.15.4?
> >>
> >> No. I seem to recall that it was more of a packet radio sort of thing
> >> (something predating 802.15.4). I could ask some folks if interested
> >> in more details...
> >
> > I think you missed my point. We have a case in point today, which is
> > IPv6 in an IPv6 tunnel encapsulation running on a packet network whose
> > MTU is 127 bytes. We call it "6lowpan", and it runs on IEEE 802.15.4.
> 
> That's not IPv6. I don't know what it is, but RFC2460 is clear on the
> minimum MTU for IPv6.

Joe is right - for IPv6 there is only one magic number (1280). Beyond
that, any size up to and including jumbograms must be accommodated,
subject to path MTU limitations.

Thanks - Fred
fred.l.templin@boeing.com

> Anyone who pays money for such a thing should return it.
> 
> Joe
> 
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