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

Mikael Abrahamsson <swmike@swm.pp.se> Mon, 30 July 2018 05:29 UTC

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Date: Mon, 30 Jul 2018 07:29:11 +0200
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Joe Touch <touch@strayalpha.com>
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Subject: Re: [Int-area] WG Adoption Call: IP Fragmentation Considered Fragile
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On Sun, 29 Jul 2018, Joe Touch wrote:

> You’re engaging in a game of escalation - whatever layer you add 
> fragmentation will end up being a layer that a vendor puts a device that 
> does DPI that fails.

Yes, but I can filter those UDP packets by looking in the UDP header, 
that's all the DPI I need in that box. It doesn't need to understand the 
upper-protocol level fragmentation, because I do not require it to 
understand that protocol at all. I just need for it to understand that 
it's UDP and look at the UDP port number.

The biggest mistake of TCP and UDP combined with IP level fragmentation is 
that the port information isn't available in every packet.

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

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