Hello everybody,
I'm experiencing a very bad network performance, when I try to connect
to a remote server.
The point-to-point connection is a E3 line, with 34MBit/s, with a cisco 2800
router on each side, terminating the point-to-point connection.
These cisco routers have two gigabit interfaces, and a serial
point-to-point E3 controller. Below my network layout:
+-------------+
|Remote Server|
+-------------+
|GigaBit Ethernet
+------------+
|Remote Cisco|
+------------+
|Serial E3 Line
|
+------------+ GigaBit Ethernet +---------+
|Local Cisco |---------------------|Linux Box|
+------------+ +---------+
|GigaBit Ethernet
+-------+
|BSD Box|
+-------+
I use iperf to measure the connection speed.
The OpenBSD box, and the Linux box are in two different networks,
so the connection between these two is also routed.
When I use iperf between the Linux-Box and the BSD-Box, then
iperf measures about 500MBit/s, so thats fine.
When I use iperf between the Linux Box and the remote server,
then I get sth. about 32 MBits, that's fine too.
When I use iperf between the BSD box and the remote server,
I only get 2MBit/s.
Then I thought, maybe the interface where the BSD box is connected
is the problem, so I connected it to the interface on the cisco,
where the Linux box was connected before, but still only the
2MBit/s speed to the remote host.
I also tried different OpenBSD boxes, with different network adaptors,
one with bge, another one with fxp, but also, no difference.
With both BSD boxes, connection to the Linux box is fast,
connections to the remote server is slow.
Then I tried to fiddle around with pf, scrub rules on the BSD box.
I tested with disabled firewall, with
scrub no-df
scrub set-tos lowdelay
scrub set-tos throughput
and some more, but without any observable difference in the speed.
The Linux box and the BSD boxes both had the same MTU on their interfaces,
and also no dropped packets, or errors on the interfaces.
When I connect the Linux box behind the OpenBSD box, and then try to connect
from the Linux box to the OpenBSD box, the performance becomes slow.
So right now I'm a bit puzzled, and have no idea, why the connection to the
remote host is fast when using a Linux box, but so slow when using OpenBSD.
Are there any differences in the IP packets that OpenBSD and Linux creates?
I'm going to capture the network traffic on the Linux and OpenBSD box to be
able
to compare the IP packets.
Is there any tool where I can replay the packet sequence on OpenBSD that I
have
recorded with tcpdump on the Linux box?
Unfortunately, I don't have access to the remote cisco, or remote
server, so I cannot check anything there.
any hint is greatly appreciated.
If there is more information needed from my side, to explain the problem,
don't
hesitate to ask.
kind regards
Sebastian
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