Date: Tue, 18 Mar 2008 15:48:57 -0500 (CDT) From: "Sean C. Farley" <scf@FreeBSD.org> To: "Bruce M. Simpson" <bms@FreeBSD.org> Cc: freebsd-net@FreeBSD.org Subject: Re: Frequent pauses with Linux-based router Message-ID: <alpine.BSF.1.00.0803181459390.7409@thor.farley.org> In-Reply-To: <47DE4E96.8080507@FreeBSD.org> References: <alpine.BSF.1.00.0803161517370.56728@thor.farley.org> <47DE4E96.8080507@FreeBSD.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, 17 Mar 2008, Bruce M. Simpson wrote:
> Sean C. Farley wrote:
>> I have noticed that with a Linux-based Netgear DG834G (DSL modem)
>> frequent pauses (example[1]) between external systems and 7-STABLE
>> (March 14th). At first, I thought it was ipfilter or ipnat, but I
>> took those out of the picture by activating telnet on the router and
>> connecting directly to it. Even running "ls /usr/sbin" on the router
>> would pause occasionally. I did not (or did not recall) have these
>> problems with 6-STABLE (post 6.2). I switched out the NIC (FA-311
>> (sis) to a FA-310 (dc)), cable and tried different ports on the modem
>> by which to connect. I also tried disabling all RFC sysctl's and
>> SACK. Nothing helped.
>>
>> Finally, I brought out an old DSL modem (SpeedStream 5660). This
>> fixed the issue. I think this maybe a specific issue between Linux
>> (2.4.17_mvl21-malta-mips_fp_le) and FreeBSD 7. Is there anything
>> else I may test to see what is happening?
>
> OT: Hang on, are you saying you're running a MIPS MALTA targeted Linux
> kernel on a Netgear DG834G? That would be interesting as a test
> platform for FreeBSD/mips, considering the platform support for Malta
> is already there. I had a go at doing the Broadcom Sentry5 SoC last
> year but hadn't finished anything.
Here is a bit of information about it from /proc:
# cat cpuinfo
processor : 0
cpu model : MIPS 4KEc V4.8
BogoMIPS : 211.35
wait instruction : no
microsecond timers : yes
extra interrupt vector : yes
hardware watchpoint : yes
VCED exceptions : not available
VCEI exceptions : not available
# cat meminfo
total: used: free: shared: buffers: cached:
Mem: 14712832 9666560 5046272 0 1130496 3694592
Swap: 0 0 0
If I was not using it for my main DSL router, I would consider putting
FreeBSD on it. After the frustration I had with it, I did seriously
wonder about FreeBSD on it. It would be especially tempting if it would
still function as a DSL router along with the web interface. :) It has
wireless, but I have that disabled. If you are interested in more
specs, I can cat /proc for you.
> Long shot, but are 802.3 pause frames appearing anywhere, ie can you
> test with a crossover cable?
> Have you done a BER test with UDP or something like that to try to
> rule out non-TCP protocols?
Well, with help on IRC from Robert Watson and others, I was able to
"fix" it. An ICMP test showed that there were occasional pauses and
packet loss. The fix: use 100Mb instead of 10Mb. :) For some reason
I do not recall, I had forced the interface connected to the DSL router
to 10Mb. When I noticed XP did not have the same problem and that it
had a 100Mb connection to the router, I found and removed the "media
10baseT/UTP mediaopt full-duplex" from /etc/rc.conf for the interface.
That appears to have fixed it.
I have never heard of pause frames. Interesting. Also, I do not recall
seeing anything unusual with tcpdump (using "host dsl" expression I
think). The pause always seemed to be for packets from the router to
the computer.
Sean
--
scf@FreeBSD.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?alpine.BSF.1.00.0803181459390.7409>