https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=240944

--- Comment #23 from [email protected] ---
This is an LRO issue for multiport Intel cards like Intel 82576 EB. 

ifconfig igb0 -lro

The main issue with Large Receive Offload (LRO) and the Intel 82576 EB (and
related Intel cards using the igb driver) is that it is incompatible with
routing/IP forwarding and bridging configurations. Using LRO in these scenarios
can lead to severe issues like performance degradation, kernel panics,
excessive TCP re-transmissions, and unstable network connectivity.

Overview of the LRO Issue
Incompatibility with Routing/Bridging: The fundamental problem is that LRO was
designed to aggregate packets within a single TCP stream on an endpoint host.
It is not designed to work correctly when the device is forwarding or bridging
traffic between different networks (which is common for multiport cards in
firewalls, routers, or virtualization hosts). The coalesced packets can cause
issues with how bridging and routing functions inspect and handle individual
frames.

# ls -la /boot/kernel/*igb*
/boot/kernel/if_igb.ko -> /boot/kernel/if_em.ko

It is a soft link to the em driver, and it works incorrectly with lro. It just
crashes the OS.

curl https://downloadmirror.intel.com/822716/igb-2.5.31.tar.gz --output
igb-2.5.31.tar.gz

Intel driver for an IGB-type network card like Intel 82576 EB (also i350)
- Unpack igb-2.5.31.tar.gz and read README file
- make && make install
This is a driver from Intel dated with the year 2024.

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