[NMLUG] speaking of Comcast... saturated upload kills connection

[KenGLong at comcast.net (Ken Long)]

This is a normal side effect of maxing out your upload bandwidth. I see 
it here at home all the time. I'm surprised the people at Comcast are 
denying all knowledge. There's no reason to pretend ignorance since the 
issue is well known.  

I experience the problem whenever I ftp a file to somewhere else and 
max out my upstream bandwidth. When that happens, all downloads slow to 
a crawl. My fix has been to use an ftp client that has bandwidth 
limiting. I set it to limit the bandwidth used to about half of my 
total upstream. That leaves enough breathing room so the downloads (web 
browsing, email, etc.) Someone else mentioned setting up traffic 
shaping in your router. That would do it too but will require some in- 
depth networking knowledge.  

BTW, I also see the problem on our fractional T1 at work when I ftp 
from there. That connection is 512K/512K so the problem is not a 
function of the asymmetrical bandwidth caps.  

That's my simplistic view of the problem <g>. Perhaps a true network 
guru could explain it in more technical terms.

Ken Long
Albuquerque


On 6 Jun 2004 at 17:37, New Mexico Linux Users Group  wrote:

> On 6 Jun 2004 at 11:47, Jason Schaefer wrote:
> 
> > I have been looking into this problem for some time now and have tested 
> > it using about 5 different modems+connections+configurations. When you 
> > upload  some place with higher download than you, 75-99% of packets are 
> > lost to or from any other connections. Same thing happens, of course, 
> > when someone downloads from you with a higher speed than your upload. I 
> > have used ftp, ssh and http to transfer files. Im using ping from a 
> > third host to verify the packet loss. Example: If a friend is 
> > downloading files from my computer I have to kill their transfer to get 
> > back on irc, check mail etc. If I am away I have to wait, for however 
> > long, to ssh in. Its that bad and its not just me.
> > 
> > Comcast has sent people out 3 times. They test signal strength and the 
> > modem and make a bunch of calls and tells me its my internal networks 
> > fault. In other words they are not responsible for anything but the 
> > modem... so naturally.  No one has a clue:-( They put me in contact with 
> > the manager and he had to clue what I was even saying, so he asked if I 
> > would write up some details. I haven't heard back. I think it must be an 
> > inherent problem, being a shared network. They insist this is not the 
> > case and they have NEVER seen it before. Has anyone else seen this 
> > problem? If you have cable give it a try and let me and, more 
> > importantly, comcast know what you find.
> > 
> > Jason