Lousy Network Performance

[Roger Oberholtzer]

On Tue, 2005-06-28 at 04:56, Kurt Wall wrote:
> Hi, list,
> 
> How do I go about solving a significant latency problem on my
> internal network. I have two computers connected via a crossover
> cable, eth1 on the "server" (luther) to eth0 on the "desktop"
> (easter). Both cards are 10/100. Ping time is atrocious:

We have tried crossover cables and come to the conclusion that they work
if they do and do not work if they don't. It seems to be related to the
specific cards (and presumably their drivers) that are connected in this
fashion. Many combinations simply do not work.

So we have decided that we will always use a switch. We found that speed
degraded over time (short time). Our applications send lots of stuff
over the network and so are sensitive to these problems. So, get a
switch or a hub.

> 
> >From luther to easter:
> $ ping -c 10 easter
> 64 bytes from easter (192.168.0.2): icmp_seq=1 ttl=64 time=893 ms
> 64 bytes from easter (192.168.0.2): icmp_seq=2 ttl=64 time=53.6 ms
> 64 bytes from easter (192.168.0.2): icmp_seq=3 ttl=64 time=910 ms
> 64 bytes from easter (192.168.0.2): icmp_seq=4 ttl=64 time=72.6 ms
> 64 bytes from easter (192.168.0.2): icmp_seq=5 ttl=64 time=930 ms
> 64 bytes from easter (192.168.0.2): icmp_seq=6 ttl=64 time=0.699 ms
> 64 bytes from easter (192.168.0.2): icmp_seq=7 ttl=64 time=960 ms
> 64 bytes from easter (192.168.0.2): icmp_seq=8 ttl=64 time=3.69 ms
> 64 bytes from easter (192.168.0.2): icmp_seq=9 ttl=64 time=979 ms
> 64 bytes from easter (192.168.0.2): icmp_seq=10 ttl=64 time=0.694 ms
> 
> --- easter ping statistics ---
> 10 packets transmitted, 10 received, 0% packet loss, time 9071ms
> rtt min/avg/max/mdev = 0.694/480.691/979.699/455.463 ms
> 
> >From easter to luther:
> $ ping -c 10 luther
> PING luther (192.168.0.1) 56(84) bytes of data.
> 64 bytes from luther (192.168.0.1): icmp_seq=0 ttl=64 time=0.418 ms
> 64 bytes from luther (192.168.0.1): icmp_seq=1 ttl=64 time=1038 ms
> 64 bytes from luther (192.168.0.1): icmp_seq=2 ttl=64 time=38.9 ms
> 64 bytes from luther (192.168.0.1): icmp_seq=3 ttl=64 time=1077 ms
> 64 bytes from luther (192.168.0.1): icmp_seq=4 ttl=64 time=77.2 ms
> 64 bytes from luther (192.168.0.1): icmp_seq=5 ttl=64 time=1116 ms
> 64 bytes from luther (192.168.0.1): icmp_seq=6 ttl=64 time=116 ms
> 64 bytes from luther (192.168.0.1): icmp_seq=7 ttl=64 time=1155 ms
> 64 bytes from luther (192.168.0.1): icmp_seq=8 ttl=64 time=155 ms
> 64 bytes from luther (192.168.0.1): icmp_seq=9 ttl=64 time=1194 ms
> 
> --- luther ping statistics ---
> 10 packets transmitted, 10 received, 0% packet loss, time 9002ms
> rtt min/avg/max/mdev = 0.418/597.109/1194.010/522.194 ms, pipe 3
> 
> I can't see any reason why the latency should be so extreme.
> 
> Kurt
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? Roger Oberholtzer          ?   E-mail: roger at opq.se        ?
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