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Re: [v6ops] PMTUD forever, was: MTUs on the general Internet

"Templin, Fred L" <Fred.L.Templin@boeing.com> Mon, 08 December 2014 16:23 UTC

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From: "Templin, Fred L" <Fred.L.Templin@boeing.com>
To: Jeroen Massar <jeroen@massar.ch>, "sthaug@nethelp.no" <sthaug@nethelp.no>
Thread-Topic: [v6ops] PMTUD forever, was: MTUs on the general Internet
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Date: Mon, 08 Dec 2014 16:23:53 +0000
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References: <5481B5C8.6030501@massar.ch> <2134F8430051B64F815C691A62D9831832DAC16A@XCH-BLV-504.nw.nos.boeing.com> <5482E29A.1070802@massar.ch> <20141206.122039.74658588.sthaug@nethelp.no> <5482F5F1.8000907@massar.ch> <2134F8430051B64F815C691A62D9831832DAD225@XCH-BLV-504.nw.nos.boeing.com>
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Subject: Re: [v6ops] PMTUD forever, was: MTUs on the general Internet
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More on what I said the other day, there are two magic numbers that tunnels
need to concern themselves with: 1280 and 1500. Accommodating all packets
within that size range while placing no explicit upper bound for accommodating
larger packets is what is being proposed. In other words, no MTU clamping.

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


> -----Original Message-----
> From: v6ops [mailto:v6ops-bounces@ietf.org] On Behalf Of Templin, Fred L
> Sent: Saturday, December 06, 2014 8:18 AM
> To: Jeroen Massar; sthaug@nethelp.no
> Cc: v6ops@ietf.org
> Subject: Re: [v6ops] PMTUD forever, was: MTUs on the general Internet
> 
> Hi Jeroen,
> 
> > -----Original Message-----
> > From: v6ops [mailto:v6ops-bounces@ietf.org] On Behalf Of Jeroen Massar
> > Sent: Saturday, December 06, 2014 4:26 AM
> > To: sthaug@nethelp.no
> > Cc: v6ops@ietf.org
> > Subject: Re: [v6ops] PMTUD forever, was: MTUs on the general Internet
> >
> > On 2014-12-06 12:20, sthaug@nethelp.no wrote:
> > >>> that should be turned off as soon as possible. That will happen as more
> > >>> and more links set MTUs larger than 1500.
> > >>
> > >> IPv6 should also have been deployed globally as soon as possible...
> > >
> > > Speaking only for myself: We run with a suitable jumbo MTU on most
> > > links *within our AS*. I see no sign of such an increased MTU becoming
> > > more available on peering and transit links.
> >
> > Agreed.
> >
> > IMHO one big reason of which is that there are cases where PMTU does not
> > work 100% and thus there is no real benefit of enabling larger MTUs as
> > it will only give problems (as it is something not well known) and thus
> > higher support cost, than creating faster transfers.
> >
> > Hence, a status quo.
> 
> Yes, the status has been quo for a long time, but we now have an opportunity
> to move beyond that. If tunnels stop clamping the MTU and end hosts start
> using RFC4821 larger MTUs will be possible. The good news is that fixing the
> tunnels and fixing the end hosts can be done independently of one another.
> 
> Thanks - Fred
> fred.l.templin@boeing.com
> 
> > Greets,
> >  Jeroen
> >
> >
> > _______________________________________________
> > v6ops mailing list
> > v6ops@ietf.org
> > https://www.ietf.org/mailman/listinfo/v6ops
> 
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