LinuxSA Mailing list archives

  From: Rick Harris <rickharris@mightylegends.zapto.org>
  To  : <eljumad@internode.on.net>
  Date: 01 Apr 2003 16:53:49 +0930

Re:

Hi eljumad,

On Tue, 2003-04-01 at 12:44, eljumad@internode.on.net wrote:
> Hi All,
> A quick pick of your brains regarding possible causes please:
> 
> We have a p3 800 with 256MB Ram box running e-smith as server and gateway. Realtek
> 8139 NICs.

Realtek NICS have a reputation for being flaky under heavy load. That
noted, we've personally had no problems with them at all (all 8139's).

> Recently upgraded it from a dial-up connection to ADSL and added the second
> NIC to do so. The client has complained that often the speed is very slow, even
> worse than when we had them on the dial-up. This speed loss is inconsistent
> though - client PCs accessing the intenet will often load webpages quickly and
> download files rapidly at 26kb/s, but then at other times hardly be able to
> load a web page properly.
> 
> My feeling is that it is the ADSL line or the modem, as they have already had
> troubles with the line in the past (ISP tested it from their end and confirmed).
> On the ADSL modem (DSL-300), the ethernet and ADSL connection lights flash furiously
> all the time, instead of staying on consistently.

This is normal for the DSL-300. The flashing represents data flow, or
internet traffic.

> 
> I can ping out of this e-smith box, either internally to hosts on the LAN or
> externally to the internet. Can also establish telnet connections to the box's
> mail ports from an external location. The e-smith resolves names to IP addresses
> fine.
> 
> Their box is also set up the same as one we have here and with the same version
> of e-smith (5.1.2), and we don't have any problems (though their symptoms sound
> like ours when the line is playing up).
> 
> My question is this: is there anything else that I can test in the e-smith to
> eliminate it as a factor in the lack of speed?

Is data being uploaded from any of the PC's when the slow-down occurs ?

My feeling is that your uplink may be getting saturated & thus
destroying your downlink.
If they can't be sure whether data is being uploaded & no-one is
admitting to it (a la the file-sharing client), run some type of
netlogger for a few days & note the slow-down periods. You can then go
back & look over the logs matching these slow times.
Ntop is a nice html-based logger that runs it's own web-server to serve
the html logs created -> http://www.ntop.org/overview.html but there's
many others.
If the upload traffic is found to be acceptable, the download problem
still exists & so you need to implement Quality of Service (QoS)
measures on the gateway.
Read here -> http://lartc.org/
In a nutshell, it can throttle designated IP's/ports & give priority to
different kinds of traffic.

Hope this helps,
Regards,
Rick



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