Re: Very slow network - Ubuntu

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A. Ben Hmeda wrote:
Marty wrote:
A. Ben Hmeda wrote:
I have searched ubuntu forums to no avail. My network connection has
slowed down considerably since I installed Ubuntu Dapper (6.06.1 LTS) I
have disabled ipv6 in /etc/aliases and Firefox, still slow by about 50%.

My machine AMDSMP is dual boot w2k/ubuntu 6.06.1 LTS (2xAthlon 2000+ 512
RAM), network is at full speed with win2k and Fedora Core 5 (now
deleted) on this machine.

I have another Ubuntu 6.06.1 LTS machine SERVER (2xP3-500 256RAM) and a
Win2k KIDPC (P3-866 512RAM) on the same home network that do not have
this problem with the network slowdowns.

My benchmark is website. Every machine on the
network has been tested separately, while other machines were turned

Didn't matter whether the connection was static or dhcp.
I have also noticed slowdowns (high latency) while playing on-line games
like bzflag
My /etc/network/interfaces :
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static

ifconfig output:

eth0 Link encap:Ethernet HWaddr 00:04:5A:9A:8C:6E
inet addr: Bcast:
RX packets:46508 errors:0 dropped:0 overruns:0 frame:0
TX packets:31020 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:43829777 (41.7 MiB) TX bytes:4368831 (4.1 MiB)

lo Link encap:Local Loopback
inet addr: Mask:
RX packets:9 errors:0 dropped:0 overruns:0 frame:0
TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:472 (472.0 b) TX bytes:472 (472.0 b)

What went wrong?

Since You are omitting some crucial details, such as the details of
your LAN
and your internet connection, for the purposes of this message I will
assume that your local LAN speed vastly exceeds the speed of your
internet connection and you are using at least 100Mb ethernet (i.e.the
typical case). Please correct me if I'm wrong.

First I would determine if you have local throughput reduction to the
machine in question. You could try testing the throughput between
machines. Unless you are using gigabit, these tests should easily
saturate your local LAN and leave no doubt about the integrity of the
local LAN.

If it turns out to be an ethernet issue, then given the lack of RX
errors on your system, I would suspect a problem on the TX side,
either in the cable or the hub/switch/router on the other end. 100mb
ethernet uses two twisted pairs of wires, and problem on only the TX
pair would be typically caused by a bad connection or a miswired cable
(e.g. incorrectly pairing the conductors in a hand-crimped cable).
Another cause is damage to RJ-45 sockets caused by plugging RJ-11 or
RJ-14 plugs into RJ-45 sockets. This can bend and permanently damage
some of the conductors in RJ-45 sockets.

If you find that it's not a physical layer (ethernet) issue, then it's
probably an IP stack or applications bug, which would make it an
extremely rare and interesting problem. I'm not a developer, but I
think the developers would be be very interested in such a problem.
Incidently I think you can disregard the claim, from another list
member, that this is not a Debian issue. Since Ubuntu is based on
Debian, any problem there could very easily apply to Etch, the next
stable Debian release.

I have an Internet router for sharing cable Internet connection. 3 PCs
plugged into this router, class C network, I think. All with static IPs,3 and 4. Gateway (router) is DNS is my ISP's I am using 100Mb Ethernet and 10/100Mb router. My Internet
connection speed is only 1Mbps (max) My internet download speeds range
from 90kB/s to 114kB/s. Under Ubuntu, they crawl at 15kB/s to 25kB/s
max! under static IP setup or dhcp setup.

The machine with the problem is my AMDSMP. I have had absolutely no
problem with network speed (internal and external) until I installed
Dapper. As it is now, it is a dual booting machine (win2k and ubuntu)

Previously, it ran Debian Sarge, Fedora Core 4 and 5, alongside win2k
without any problems. Presently, my network speed is fine under windows,
was fine under Sarge, Fedora 4 and 5 on the same machine, except for

As I was poking around, trying to figure this out, I noticed that
network speed is drastically improved, back to 90kB to 114kB under
Ubuntu when, in GNOME, I open the System>>Administration>>Networking and
just click OK, without actually changing anything! This makes no sense
to me and I have no explanation for it, it certainly does not change the
content in my /etc/network/interfaces but I was able to duplicate the
steps with same results every time. Is the
System>>Administration>>Networking>>OK the same as
/etc/init.d/networking restart?

Thanks for your help

Have you considered trying something other than Ubuntu? There are many
other GNU/Linux distributions that work (and some much better). Ubuntu
may be popular, but that doesn't make it the best. Same can be said
with the current industry leader's operating system.

If you want to use Debian, we can help you. If you want to try
something else, take a look at and have a look at
the hundreds of choices.

Interesting that your network problem magically fixes itself when you
try to configure it and do nothing. Is there a ghost in the machine?


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