On Fri, Oct 24, 2008 at 03:54:01PM +0200, Christoph Leser wrote: > > -----Urspr|ngliche Nachricht----- > > Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > > Im Auftrag von Otto Moerbeek > > Gesendet: Freitag, 24. Oktober 2008 13:11 > > An: Sebastian Reitenbach > > Cc: misc@openbsd.org > > Betreff: Re: slow network performance behind cisco > > > > > > 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 > > > > > > If it is a buffer size problem, why can he transmit 500mb/sec between bsd and > local linux? >
Because the delay between the two machines is very low. It appears you need to read about bandwidth-delay product as well.
