Strange network behaviour
Vincent Zee
basics at zenzee.cistron.nl
Sat Apr 12 10:03:16 PDT 2003
>>Vincent Zee <basics at zenzee.cistron.nl> writes:
>
>> On 09 Apr 2003 16:39:03 -0400, Lowell Gilbert wrote:
>> > Vincent Zee <basics at zenzee.cistron.nl> writes:
>> >
>> >> I am really at a loss at the moment.
>> >>
>> >> I have a 100baseT network at home and all connected machines have
100Mb
>> >> network cards.
>> >> When I upload mp3 files from my ibook to the FreeBSD server the speed
>> >> drops to 100kb/s.
>> >>
>> >> This only happens between these two particular machines. These same
>> >> machines connected to other machines give the expected transmission
>> >> speeds. I checked cables, switches and router but found nothing
>> >> unexpected.
>> >>
>> >> Any hints, ideas or even solutions are most welcome.
>> >>
>> >> The FreeBSD machine is running 4.7 and the ibook 10.2.4
>> >
>> > This sounds a lot like a duplex mismatch.
>> > Check the collision count.
>>
>> Hi Lowell,
>>
>> thank you for your answer(:-))
>>
>> Here is the ifconfig output for the nic in the freebsd machine:
>>
>> dc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
>> inet 192.168.1.10 netmask 0xffffff00 broadcast 192.168.1.255
>> inet6 fe80::248:54ff:fe12:c767%dc0 prefixlen 64 scopeid 0x1
>> ether 00:48:54:12:c7:67
>> media: Ethernet autoselect (100baseTX <full-duplex>)
>> status: active
>>
>> Here is the ifconfig output for the nic in the ibook:
>>
>> en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
>> inet6 fe80::20a:95ff:fe67:2460%en0 prefixlen 64 scopeid 0x4
>> inet 192.168.1.3 netmask 0xffffff00 broadcast 192.168.1.255
>> ether 00:0a:95:67:24:60
>> media: autoselect (100baseTX <full-duplex>) status: active
>> supported media: none autoselect 10baseT/UTP <half-duplex>
>> 10baseT/UTP <half-duplex,hw-loopback> 10baseT/UTP <full-duplex>
>> 10baseT/UTP <full-duplex,hw-loopback> 100baseTX <half-duplex> 100baseTX
>> <half-duplex,hw-loopback> 100baseTX <full-duplex> 100baseTX <full-
>> duplex,hw-loopback>
>>
>>
>> Here is the output of netstat -i during a transmission of a 14 MB file.
>>
>> -bash-2.05b$ netstat -i
>> Name Mtu Network Address Ipkts Ierrs Opkts Oerrs
>> Coll
>> dc0 1500 <Link#1> 00:48:54:12:c7:67 5734078 0 5911495 0
>> 0
>> dc0 1500 192.168.1 freeserv 5728716 - 5910566 -
>> -
>> dc0 1500 fe80:1::248 fe80:1::248:54ff: 0 - 0 -
>> -
>> lp0* 1500 <Link#2> 0 0 0 0
>> 0
>> faith 1500 <Link#3> 0 0 0 0
>> 0
>> lo0 16384 <Link#4> 375 0 375 0
>> 0
>> lo0 16384 ::1 ::1 0 - 0 -
>> -
>> lo0 16384 fe80:4::1 fe80:4::1 0 - 0 -
>> -
>> lo0 16384 your-net localhost 375 - 375 -
>> -
>> ppp0* 1500 <Link#5> 0 0 0 0
>> 0
>> sl0* 552 <Link#6> 0 0 0 0
>> 0
>>
>> /\
>> Vincent
>
>Okay, so there are no collisions on the FreeBSD side.
>Check whatever it's plugged into (a switch?).
>If *that* thinks the link is half duplex while FreeBSD thinks it's
>full duplex, you've found your problem.
--------------------------------------------------
Mike wrote:
>Hi:
>
>I'm experiencing the same issue from a PowerMac 733 with OS 10.2.4 =
>(which
>is, to my mind, pretty FreeBSD like) to several different FreeBSD =
>machines
>running 4.5 and 4.7 respectively. I know there aren't any duplex =
>problems
>and I'm not experiencing the issue when I go from either the Mac or =
>FreeBSD
>boxes to other hosts.
>
>In doing a TCP dump it looks like packet loss, although it only occurs
>between these hosts. The ack is sent by the Mac but the BSD box doesn't =
>see
>it, so the Mac re-acks (up to 4 times usually) before the BSD box acks =
>the
>ack at the end of its Window. Everything slows to a crawl until that =
>one
>dropped packet is acked.
>
>Hrmm. Has anyone else seen this? I'm thinking it's an issue on the =
>Mac
>side, but who knows.
>
>Mike
>
Hi Lowell and Mike,
sorry for the late reply but the ibook in question stopped working a few days
ago and I lost all my mail as a result.
The switch saw the connection as 100Mb and full duplex so it wasn't the
switch.
Mike is describing my situation exactly. So now I really think that it is a
Mac specific thing.
Thanks Mike for letting me know I'm not crazy (;-))
Vincent
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