So I finally got tired of dealing with this speed degradation issue
plaguing me since ubuntu hardy, and decided to put some work in on
figuring out what the issue was, and I think I have. Since this issue
seems apparent in literally anyone I've tried using Ubuntu on a Cox
network (and some of you substantiated), I think this probably would
apply to most of you on this list. I suspect the problem isn't limited
only to ubuntu, but don't have other distro's to test with. Anyways...
The primary issue was downloads, primarily apt updates in ubuntu, and
other random large http downloads would suffer an extreme speed drop
within seconds of starting. Literally going from 400-500kb/s to bytes
(snail time). Easily tested using cli 'sudo apt-get -d install
linux-image-2.6.27-14-generic' or any other big .deb file. If it starts
fast and slows to a halt, read on.
I first suspected Cox, but ruled this out trying even a new docsis 3.0
modem with no benefit. Once I'd ruled out the ISP, I began testing my
internal network and my computer. Ultimately I then began tweaking with
sysctl's, adding in some network performance items I typically throw
into webservers and such. I found that tcp window scaling seems to be
the root of the evil. Disabing it resolved the issue:
sudo sh -c "echo 'net.ipv4.tcp_window_scaling = 0' >> /etc/sysctl.conf"
sudo sysctl -p
Instantly I'm getting a solid 400kb/s of transfer on my apt's again,
as I'd expect.
I'm going to begin looking into more why that seems to be an issue
either as a general problem with the ubuntu sysctl config issue, a linux
tcp stack issue, or something funky with cox that works against RFC1323.
I've seen this issue on 3 separate pc's (and switch/firewalls with them)
myself at different houses around the valley, so I know I'm not the only
one with this issue. I just don't know how far the rabbit hole goes.
I'd like to know if this fixes anyone else seeing the same issues. Let
me know your results please!
wtf is this sysctl for or rfc1323?
http://ipsysctl-tutorial.frozentux.net/chunkyhtml/tcpvariables.html#AEN505
-mb
---------------------------------------------------
PLUG-discuss mailing list -
PLUG-discuss@lists.plug.phoenix.az.us
To subscribe, unsubscribe, or to change your mail settings:
http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
(text/plain)