[Bug 293227] VNET jail regression on 14-STABLE from 14.3 using bridge and epair

From: <bugzilla-noreply_at_freebsd.org>
Date: Tue, 17 Feb 2026 08:54:39 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=293227

Timo Voelker <timo.voelker@fh-muenster.de> changed:

           What    |Removed                     |Added
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                 CC|                            |timo.voelker@fh-muenster.de

--- Comment #1 from Timo Voelker <timo.voelker@fh-muenster.de> ---
(In reply to Tom Hukins from comment #0)

My understanding of your problem is that a sender keeps sending packets that
are too large and it seems to ignore the ICMP Packet Too Big messages. What I
don't get is how your setup looks like. I tried to reproduce the problem with
the following setup.

 Jail           Jail                 Jail             Jail
sender         router1              router2         receiver
epair0b --- epair0a epair1a --- epair1b epair2a --- epair2b
1::2/64     1::1/64 1:2::1/64  1:2::2/64 2::1/64    2::2/64
                    MTU 1400   MTU 1400

I configured sysctl net.inet6.ip6.forwarding=1 on router1 and router2.

With nc, I let the sender send a 200 KB file to 2::2. It starts sending 10
packets that are too large. router1 responds on each packet with a ICMP Packet
Too Big message. The sender notices these messages and sens IP packets not
larger than 1400 B from then on.

Looks all good to me. Can you give more details on how your test setup looks
like?

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