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Re: Asymmetric gigabit speeds / OpenBSD 3.7 PF



On Thu, Jun 16, 2005 at 04:57:19PM +0200, Frederic BRET wrote:
> I was not sure where to send this question, to an OpenBSD list or to the 
> PF list. I'm trying to understand why our OpenBSD PF router is not able 
> to cope correctly with needed gigabit speeds, and perhaps one of you 
> already encoutered this with his PF....
> 
> I have two Dell 1750 single-Xeon 2.8GHz. The first is our production 
> router still under OpenBSD 3.4 beta with PF since 2 years, and the 
> second one is a fresh OpenBSD 3.7 under Generic stock kernel. The 
> ultimate goal beeing to build a CARP dual router with the 2 machines.
> 
> The problem is that none of the 2 machines is able to route at speed 
> higher than ~350mbit/s, even without PF which could slow things, what I 
> doubt of.
> 
> In order to validate the capacity of the server to cope with 
> simultaneous up/down gigabitstreams, I've done several tests
> 
> - First, validate the external test machine and the network.
> Here is a simultaneous (-d) iperf TCP test between 2 Sun V40Z (SLES9 
> with Broadcom 5703). Between them, there's a HP Procurve 2824 Gigabit 
> switch with full-duplex enabled and properly negotiated on all ports :
> ROOT:Linux:/opt/iperf2/bin > ./iperf -i 1 -c <Linux iperf server 
> address> -d -w 256k
> ./..
> [  4]  0.0-10.0 sec  1.01 GBytes    864 Mbits/sec
> [  5]  0.0-10.0 sec  1.01 GBytes    865 Mbits/sec
> => The network AND the V40Z are capable of symetric quasi full-duplex 
> gigabit. OK
> 
> - This beeing said, I'll try to do the same thing between a V40Z and a 
> DELL 1750 (OpenBSD 3.7 with Broadcom 5704)
> First lets do a non-simultaneous (-r) TCP test between the V40Z and a 1750
> ROOT:Linux:/opt/iperf2/bin > ./iperf -i 1 -c <OpenBSD iperf server 
> address> -r -w 256k
> ./..
> [  4]  0.0-10.0 sec  1.09 GBytes    935 Mbits/sec
> [  4]  0.0-10.0 sec  1.09 GBytes    938 Mbits/sec
> => More than 1GB are transfered in 10s in one way then in the other. 
> Unidirectionnal bandwidth of 1Gbits/s is almost respected, no problem.
> 
> - Now lets try simultaneously (-d) between the V40Z and the DELL 1750 
> like the first iperf test between the 2 linux boxes :
> ROOT:Linux:/opt/iperf2/bin > ./iperf -i 1 -c <OpenBSD iperf server 
> address> -d -w 256k
> ./..
> [  4]  0.0-10.0 sec    403 MBytes    338 Mbits/sec
> [  5]  0.0-10.0 sec  1.02 GBytes    876 Mbits/sec
> => The Openbsd box isn't able to receive more the ~330Mbits/s every time 
> I tried when it's at the same time speeking through the wire. It's a 
> constant comportment.
> 
This sound like the fameous hlt hlt problem. I think a fix went into
3.7-stable or else try -current to see if this helps.
-- 
:wq Claudio