Poor eth0 through put

Poor eth0 through put

[John J. Bauerly]

Hello All;

Another weekend and no progress. I compiled a new kernel for ax25 installed 
and it seems to be ok. However when I went to send the tgz down the lan to 
the backup machine, ftp is choking. Any file greater than 25k will not 
transfer using ftp. I pinged the machines found a high error rate between 
the 2 machines. I brought a third on line and both will work fine to it 
under RH6.2. Hum. I booted the 2 problem machines into windows. Ping and 
file transfer are ok if one or both are running windows. Don't want to run 
windows. Since then I reloaded both machines with RH6.2 orginal kernel. 
Checked and made sure which packages are running. The hardware is the same 
between the 2 that are failing and the third. To me it does not look like a 
hardware problem. It looks like a setup problem in Linux. But I have set 
software and bios the same. What else can I check and improve the lan 
performance?


John J. Bauerly NW0I

Re: Poor eth0 through put

[M Taylor]

On Sun, Oct 13, 2002 at 06:04:48PM -0500, John J. Bauerly wrote:
> Hello All;
> 
> Another weekend and no progress. I compiled a new kernel for ax25 installed 
> and it seems to be ok. However when I went to send the tgz down the lan to 
> the backup machine, ftp is choking. Any file greater than 25k will not 
> transfer using ftp. I pinged the machines found a high error rate between 
> the 2 machines. I brought a third on line and both will work fine to it 
> under RH6.2. Hum. I booted the 2 problem machines into windows. Ping and 
> file transfer are ok if one or both are running windows. Don't want to run 
> windows. Since then I reloaded both machines with RH6.2 orginal kernel. 
> Checked and made sure which packages are running. The hardware is the same 
> between the 2 that are failing and the third. To me it does not look like a 
> hardware problem. It looks like a setup problem in Linux. But I have set 
> software and bios the same. What else can I check and improve the lan 
> performance?

What NICs are you using? 3Com 3c905b or $2 Realtek 8139 based card? Or some
8-bit WD*008 ISA card?

What is the physical wiring? (Cross over cables, a cheap noname hub, or a
known good Cisco switch) 

Have you tested with the newest Red Hat provided kernel for 6.2? (2.2.18-5
I think but am not certain)

Check dmesg, /var/log/messages (grep for NET, eth, IP), /var/log/boot.log

Try /etc/rc.d/init.d/networking restart
and check the log files again for errors/warnings.

Check any/all blinking lights on NICs, hubs, switches. Look for collision
light(s), and see if it lit often.

You could upgrade to RedHat 7.3, or RH 8.0. 

-ve1mct

Re: Poor eth0 through put

[Tapio Sokura]

>and it seems to be ok. However when I went to send the tgz down the lan to 
>the backup machine, ftp is choking. Any file greater than 25k will not 
>transfer using ftp. I pinged the machines found a high error rate between 
>the 2 machines. I brought a third on line and both will work fine to it 
>under RH6.2. Hum. I booted the 2 problem machines into windows. Ping and 
>file transfer are ok if one or both are running windows. Don't want to run

One possible reason is incompatible duplex-settings, i.e. the problematic 
computer is talking half-duplex to a switch that is expecting full-duplex 
or the computer is using full-duplex to a switch/hub expecting half-duplex.

So check the lights on your network cards, hubs and switches to make sure 
that the speeds are the same (probably are because you are getting 
something through) and the duplex settings are the same.

Depending on your network cards and hubs/switches it's often possible to 
force full-duplex or half-duplex on either or both ends instead of the 
normal autodetection. Often these settings can be changed in Linux by using 
module parameters or some configuration tool (mii-tool for many 100 Mbit 
cards, for example). If the problematic computer is connected to a hub, the 
correct setting is half-duplex, switches can use both half and full duplex 
(obviously full duplex is faster if it works).

Re: Poor eth0 through put

[Wilbert Knol]

On Sun, 13 Oct 2002, John J. Bauerly wrote:

> transfer using ftp. I pinged the machines found a high error rate between 
> the 2 machines. I brought a third on line and both will work fine to it 

Another thing to look out for is that you are using the latest driver for 
the network card. I had similar problems with (from memory) a Tulip card, 
at work, also on a RH distro, and, after a quick web search, found a 
much later driver, which cured it.

Have a look in /usr/src/linux/Documentation/networking for the
info file on your card. You may be able to turn off DMA on the NIC, which 
could make a difference if there is a DMA conflict.

if the machine is dual-bootable, another trick is to look at the resources 
for the card under Windows (DMA, IRQ etc), and compare them to those 
Linux. You could then fix them the same under Linux (turn PnP off)

if your LAN is ethernet coax, you did remember to put the terminating 
resistors on the Tees, didn't you??

> file transfer are ok if one or both are running windows. Don't want to run 
> windows. 

Too right.

A collegue gave me a demo of the Cross-over Wine package the other day: he 
fired up Internet Explorer on his KDE desktop <grin>


Wilbert, ZL2BSJ