Date: Mon, 11 Mar 2002 10:28:59 +1100 (EST) From: callum.gibson@db.com To: hackers@freebsd.org Subject: Bad network performance after 4.5 upgrade Message-ID: <20020311042739.47780.qmail@merton.aus.deuba.com>
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Hi,
I have a FreeBSD box connected to another via a dual-channel isdn router
(64+64k). The way this works is that if sustained throughput is detected
the second channel on the router (cisco 770) automatically comes up
giving throughput of around 14k/sec (or 7k/sec for a single channel).
One was running 4.3, the other 4.4. Recently I upgraded the 4.3 machine
(which is plugged directly into the router) to 4.5 and noticed an immediate
problem with the network upload throughput. Since I was intending to upgrade
the other machine anyway I suspended judgement until then. Having done so
the problem persists, which is this: as soon as the second channel cuts
in the network throughput splutters to a halt. For example, when using
scp or ftp it tells me the connection has stalled. The second channel
then automatically drops out again due to no network activity (as indicated
by the leds). New network sessions can usually be started ok, but it
takes quite a while for the scp transfer to recover and the cycle repeats.
Initially I suspected the openssh software (since this would have changed
with the upgrade), but I have upgraded it and then also noticed the same
behaviour with X11 connections, ftp, etc. Additionally, scp transfers
between the FreeBSD box and a Solaris 2.6 box across the isdn line behave
as expected with the second channel clicking in and staying up, instead
of just dying. I've discounted the idea that it's the network driver
per se, since it works fine to Solaris and is okay when downloading.
Help! Is there some sort of sysctl tweak? I wonder if some sort of timing
is being thrown out by the brief delay as the second channel comes up.
I witnessed a bit of talk in hackers around December about tcp changes
and a bit of recent activity mentioning patches. At this stage, though,
it seems like the 4.5 upgrade has stuffed my network throughput in one
direction.
Here is the ifconfig and dmesg output for the affected end. The isdn router
is a cisco 770.
xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=3<rxcsum,txcsum>
inet6 fe80::2c0:4fff:fe60:ad0d%xl0 prefixlen 64 scopeid 0x1
inet 10.179.46.21 netmask 0xfffffff8 broadcast 10.179.46.23
ether 00:c0:4f:60:ad:0d
media: Ethernet 10baseT/UTP <full-duplex>
status: active
xl0: <3Com 3c905B-TX Fast Etherlink XL> port 0xec00-0xec7f mem 0xfe008000-0xfe00
807f irq 10 at device 17.0 on pci0
xl0: Ethernet address: 00:c0:4f:60:ad:0d
regards,
Callum
(c)2002 Callum Gibson callum.gibson@db.com
Global Markets IT, Deutsche Bank, Australia 61 2 9258 1620
### The opinions in this message are mine and not Deutsche's ###
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