PF in FreeBSD 5.3 versus 6.x

Matthew Franz mdfranz at
Sun Oct 14 16:51:02 PDT 2007

HI Michael,

You don't say whether you are running pfsync because Bill Marquette
(who I work with) and Max have been discussing a pretty nasty pfsync
bug (on 6.2) on this list under high loads (probably starting where
you are at in terms of pps throughput but going up to 70-90kpps) where
the backup is unable to clear states and there is eventually a huge
discrepancy between the master and the backup.

If you are seeing this with a single box. Its on my list to try to
reproduce this in the lab (and test some of the patches Max has
developed) with smartbits but I still haven't had time. We are
definitely seeing some PF losing state entries, but sort of assumed
this was a pfsync issue (or an effect thereof) but if you are seeing
this without pfsync, that would point to so more fundamental problems
with PF under high load. I can also share so more specific stats
offline if that would be helpful.

- mdf

On 10/9/07, Michael Conlen <m at> wrote:
> I've noticed at some point between 5.3 and 6.0 that PF seems to be
> dropping more packets than with 5.3 and there is increased deviation
> in latency. Using the same equipment handling about 25k PPS each way
> I see about 0.3% packet loss with FreeBSD 6.2 and 6.0 with sub 0.1%
> loss with FreeBSD 5.3.  Similarly the worst case response times for
> ICMP packets is much less in 5.3 than in either version of 6.
> I'm using something pretty vanilla in terms of setup. No ALTQ support
> or features, no redirects, just a lot of blocking and allowing. The
> firewalls are using server class 3Com and Intel Gigabit (Fiber)
> cards. The changes were noticed going forward and undone by going
> back to FreeBSD 5.3 so I don't suspect physical problems at the moment.
> My pf.conf is essentially a block in all followed by a block in quick
> against a table with 2000 entries, many of the /24 or /16 followed by
> pass rules to the various host:ports we allow.
> If I login to the firewalls themselves and run mtr in each direction
> I don't see any traffic loss. It's only when crossing the firewalls.
> Usage is about 25k packets per second and 100Mbit/sec 5 minute max
> traffic. The switches are Foundry SI-800g.
> Also doing about 25k/sec searches with 400 inserts a second and 270
> removals and 407 matches/sec. The state table seems to run about
> 70,000 to 90,000
> Are there issues I should be aware of and should pf be able to handle
> this kind of load?
> --
> Michael Conlen
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Matthew Franz

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