On Fri, Oct 24, 2008 at 12:58:27PM +0200, Sebastian Reitenbach wrote: > 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.
OpenBSD uses a pretty low default send and receive buffer size for sockets. Try increasing net.inet.tcp.recvspace and net.inet.tcp.sendspace, after reading a bit about bandwidth * delay products. -Otto > > If there is more information needed from my side, to explain the problem, > don't > hesitate to ask. > > kind regards > Sebastian > > _______________________________________________________________________ > Jetzt neu! Sch|tzen Sie Ihren PC mit McAfee und WEB.DE. 30 Tage > kostenlos testen. http://www.pc-sicherheit.web.de/startseite/?mc=022220