pf stalls connection when using route-to

[Lin Jui-Nan Eric]

Hi listers,

We recently found that when the traffic passes pf with route-to, the
connection stalls.
Turning off TSO solves the problem. Our pf.conf is very simple:

table <privip> const {10/8, 172.16/12, 192.168/16}
pass out quick route-to (em0 10.1.1.1) from <privip> to ! <privip> no state

And we have a tcpdump capture file. It shows that there's lots of
duplicate packets and
retransmissions while TSO is enabled. Our NIC is an Intel PRO/1000:

em0: <Intel(R) PRO/1000 Network Connection 6.9.14> port 0x2000-0x201f
mem 0xdf200000-0xdf21ffff irq 18 at device 0.0 on pci4
em0: Using MSI interrupt
em0: [FILTER]

Screenshot: http://cf.files.jnlin.org/with-tso.png

Any suggestion? I just turn off the TSO, but I think it is only a workaround.



Sincerely,

                Jui-Nan