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From: "Toke Høiland-Jørgensen" <>
Cc: Leon Schuermann <>
Subject: Re: [RFC PATCH 0/4] Introduce per-peer MTU setting
Date: Tue, 04 Jan 2022 22:34:35 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <> writes:

> From: Leon Schuermann <>
> This patch series is an attempt to integrate a per-peer MTU setting
> into WireGuard. With matching changes to the wireguard-tools,
> individual MTU values can be set and retrieved for each registered
> peer.
> While Linux supports setting an MTU metric for specific FIB route
> entries [which I've only found out after implementing this :)], and
> thus allows to lower the MTU for individual peers, this appears to
> disable regular path MTU discovery (PMTUD) entirely on the
> route. While regular PMTUD does not work over the tunnel link, it
> should still be usable on the rest of the route.

I'm not sure I understand the use case? Either PMTUD works through the
tunnel and you can just let that do its job, or it doesn't and you have
to do out-of-band discovery anyway in which case you can just use the
FIB route MTU? Or what do you mean by "usable on the rest of the route"?

> Furthermore, with the goal of eventually introducing an in-band
> per-peer PMTUD mechanism, keeping an internal per-peer MTU value does
> not require modifying the FIB and thus potentially interfere with
> userspace.

What "in-band per-peer PMTUD mechanism"? And why does it need this?


  parent reply	other threads:[~2022-01-04 21:34 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-28 23:45 leon
2021-12-28 23:45 ` [RFC PATCH 1/4] netdevice: add ndo_lookup_mtu for dynamically determining MTU leon
2021-12-28 23:45 ` [RFC PATCH 2/4] net/ipv4: respect MTU determined by `ndo_lookup_mtu` leon
2021-12-28 23:45 ` [RFC PATCH 3/4] net/ipv6: " leon
2021-12-28 23:45 ` [RFC PATCH 4/4] net/wireguard: add per-peer MTU setting leon
2022-01-04 21:34 ` Toke Høiland-Jørgensen [this message]
2022-01-07 22:13   ` [RFC PATCH 0/4] Introduce " Leon Schuermann

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