Performance

Omar omar@natasha.org
Fri Oct 15 12:34:30 1999


Ok, in an effort to figure out if the problem is with linux and the tulip 
card (linksys), i decided to hook up another computer on the same hub as 
the cable modem.
so now the next time this intermittent stuff happens again i'll try pinging 
both computers to see what happens.

I don't know the details of my neighbor, when i said neighbor i meant 
someone living in the same city. you can tell because when you ping someone 
on the same subnet it also shows their hostname which has the city name and 
customer id number in it.  so i pinged two random customers who are in my 
city, and both had 0 packet loss but i had 60% or more packet loss...then 
about 30 minutes later, it went away and i had 0% packet loss again...weird eh?
i didn't install any splitters myself, they did it all.
they might come tomorrow to check it out, i'm on a waiting list for saturday
thanks for the help!



At 03:44 AM 10/15/1999 , Ed Clarke wrote:
> > hey guys,
> > is ping a good way to determine connectivity problems??
>usually.
>
> > for example,, when i ping my home linux box through the cable modem.
> > it has 38% to 50% packet losses, intermittently througout the day
> > but if i ping my neighbor's windows95 computer through his cable modem, i
> > get 0% packet loss from the SAME source...........which leads me to
> > believe either my cable
> > modem is bad, or my linux box and card or is ping something that works
> > different with linux and/or windows?
>Works the same.
>
>What's not the same is your environment.  I spend some of my time keeping
>a cable modem system up and running.  Is your neighbor on the same cable
>amplifier that you are on?  That eliminates half of the problem ( the
>cable system itself ).  If so then the signal at the modem may be too
>low for some reason - crappy splitters for example.  If you bought a
>splitter at Radio Shack, it may not pass back the low return channels
>( < 40 MHZ ) without serious degradation.  Your modem may be turned down
>for some reason too.  I can set power output for our modems remotely and
>so can your cable system.  Call them; they can run remote diagnostics on
>your system and fix the problem remotely if it's not a hardware problem
>inside your house.  If you've added splitters, you may have cut the signal
>level down too far for good connectivity on the receive side.
>
>A current example:
>
>.nodeRemod.nrMonitor.nrMonitorNoiseLevel = -26
>.nodeRemod.nrMonitor.nrMonitorPowerLevel.0 = 10
>
>The noise figure on the system at this time is -26 (no particular units)
>and my power level is 10dbmv.  I check the modems on the system and raise
>and lower their outputs to keep the same return signal level at the
>node remodulator for all modems.  That way someone with a hot modem doesn't
>kill someone with a low output modem due to AGC.
>
>If the noise figure drops below -24, then there's a problem with the trunk
>line somewhere (on THIS system).  This could be caused by lots of things -
>some turkey with an illegal CB amplifier causing ingress to the cable return,
>a bad return amp etc. etc. etc.  Or you could have a bad modem ... 8-)