RE: Space for Packet Metadata

Nick Banks <nibanks@microsoft.com> Wed, 28 February 2018 15:30 UTC

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From: Nick Banks <nibanks@microsoft.com>
To: "Eggert, Lars" <lars@netapp.com>, =?utf-8?B?TWlra2VsIEZhaG7DuGUgSsO4cmdlbnNlbg==?= <mikkelfj@gmail.com>
CC: IETF QUIC WG <quic@ietf.org>
Subject: RE: Space for Packet Metadata
Thread-Topic: Space for Packet Metadata
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Date: Wed, 28 Feb 2018 15:30:23 +0000
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According to spec, QUIC requires at least 1280 (from 9.4):

"QUIC depends on the network path supporting a MTU of at least 1280 octets. This is the IPv6 minimum MTU and therefore also supported by most modern IPv4 networks. An endpoint MUST NOT reduce its MTU below this number, even if it receives signals that indicate a smaller limit might exist.'

- Nick

-----Original Message-----
From: QUIC <quic-bounces@ietf.org> On Behalf Of Eggert, Lars
Sent: Wednesday, February 28, 2018 7:12 AM
To: Mikkel Fahnøe Jørgensen <mikkelfj@gmail.com>
Cc: IETF QUIC WG <quic@ietf.org>
Subject: Re: Space for Packet Metadata

On 2018-2-28, at 16:03, Mikkel Fahnøe Jørgensen <mikkelfj@gmail.com> wrote:
> Yes, but can it go below 1200? It seems the handshake aims to squeeze up near the minimum guaranteed (required) PMTU and QUIC implementations would probably not expect to maintain a connection that drops below PMTU 1200.

The minimum IPv4 MTU is 576, so I'd expect QUIC stacks to probe as least that low.

Lars