Development discussion of WireGuard
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From: Roman Mamedov <rm@romanrm.net>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Luis Ressel <aranea@aixah.de>,
	WireGuard mailing list <wireguard@lists.zx2c4.com>,
	Roman Mamedov <rm.wg@romanrm.net>
Subject: Re: Mixed MTU hosts on a network
Date: Sat, 14 Apr 2018 20:20:29 +0500	[thread overview]
Message-ID: <20180414202029.5f247fba@natsu> (raw)
In-Reply-To: <CAHmME9ra=DZiaUS7pP3xAxC_7H-yqfiTefU3Q8gufpP7e6H2zw@mail.gmail.com>

On Sat, 14 Apr 2018 16:45:32 +0200
"Jason A. Donenfeld" <Jason@zx2c4.com> wrote:

> In this case, WireGuard seems to be doing the right thing. Think you
> could come up with some minimal test that exhibits the behavior you're
> seeing?

I now remember in more detail what was the problem. It was not with MTU 1412
on both sides, it was during trying to mix WG MTU 1412 on the PPPoE-connected
machine, with WG MTU 1420 on the other side (which uses full 1500 underlying
MTU).

Here I posted about it with some tcpdumps included:
https://lists.zx2c4.com/pipermail/wireguard/2018-March/002537.html

With 1420 on the "full MTU" side, the "PPPoE" side had to set 1408 WG MTU for
things to work properly, not 1412 as would theoretically fit into its PPPoE.

I'll post an update if I come up with a short and simple reproducer sequence.

Setting 1412 on both sides seems to work fine from more testing just now.

-- 
With respect,
Roman

  reply	other threads:[~2018-04-14 15:06 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-16  9:25 Roman Mamedov
2018-03-16  9:35 ` Matthias Ordner
2018-03-16 10:53   ` Roman Mamedov
2018-03-16 16:20     ` Roman Mamedov
2018-03-16 10:01 ` Kalin KOZHUHAROV
2018-03-26 19:12 ` Luis Ressel
2018-04-14  1:38 ` Jason A. Donenfeld
2018-04-14  2:40   ` Jason A. Donenfeld
2018-04-14 13:16     ` Jason A. Donenfeld
2018-04-14 13:40       ` Roman Mamedov
2018-04-14 14:15         ` Jason A. Donenfeld
2018-04-14 14:38           ` Roman Mamedov
2018-04-14 14:45             ` Jason A. Donenfeld
2018-04-14 15:20               ` Roman Mamedov [this message]
2018-04-14 23:08                 ` Jason A. Donenfeld

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