Re: [Int-area] WG Adoption Call: IP Fragmentation Considered Fragile

Joe Touch <> Thu, 02 August 2018 15:19 UTC

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From: Joe Touch <>
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Date: Thu, 2 Aug 2018 08:19:07 -0700
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Subject: Re: [Int-area] WG Adoption Call: IP Fragmentation Considered Fragile
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> On Aug 2, 2018, at 8:02 AM, Mikael Abrahamsson <> wrote:
>> On Thu, 2 Aug 2018, Joe Touch wrote:
>> Just because operators/vendors “want” to do otherwise does not make it possible.
> I've been on hotel wifis that are behind 3 layers of NAT, PMTUD non-working, PMTU is like 1450, and the only thing saving the day is TCP MSS adjust, so the only thing that works is something over TCP or that happens to use small enough packets. I have been on other networks where basically only thing that works is 80/443 and some mail related ports. Complaining doesn't help, because peoples mobile phones work ok.
> It's "possible", because it works well enough for what some people use it for. Very few complain, so there is no improvement.
> So while you're technically and formally right, there is no enforcement and the only thing we can do is write requirements, tests, educate, but also educate application and protocol developers on what they might face in the real world. This is engineering, not physics. Real world is more important than map.
> IP-fragmentation has always been fragile, and it's not improving. The Internet is growing, so this is not getting better. This is reality, even though we do not like it.

So you want us to redesign the Internet to run over port 443.

As you said, “this is reality, even if we don’t like it”.

The again, IP has fragmentation. That too is reality, even if we don’t like it.

Again, something broken needs fixing. You can chase the symptoms forever or you can deal with the cause. It’s simply not tenable to ‘fix’ the internet to accommodate broken devices.