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

Mikael Abrahamsson <swmike@swm.pp.se> Fri, 27 July 2018 13:32 UTC

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Date: Fri, 27 Jul 2018 15:32:20 +0200
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Ole Troan <otroan@employees.org>
cc: Joe Touch <touch@strayalpha.com>, "internet-area@ietf.org" <int-area@ietf.org>, "intarea-chairs@ietf.org" <intarea-chairs@ietf.org>
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Subject: Re: [Int-area] WG Adoption Call: IP Fragmentation Considered Fragile
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On Fri, 27 Jul 2018, Ole Troan wrote:

> There's nothing intrinsic in tunnels that require network layer 
> fragmentation. The current IP in IP / GRE etc tunnel implementations do, 
> but in principle we could design tunnel fragmentation/reassembly above 
> the network layer.

This is what I do with OpenVPN for instance. I tell it to application 
layer fragment at ~1400 bytes, so the resulting packets always are 
significantly below 1500 bytes. So even as the inside of the tunnel is 
9000 MTU clean, it never results in IP fragments to be transported.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se

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