View Full Version : [ubuntu] [SOLVED] etnernet link issue

November 9th, 2008, 10:18 AM

i run a Fedora 9 Server and Ubuntu 8.04 desktop and experience reduced link speed, regardless of protocol. I've tried samba, ftp, sftp, ssh etc, but end up with a rate of about 2.5 Mbyte / Second when copying files in either direction.

The link speed is 100MB/s, according to 'ethtool eth0' at my Ubuntu desktop:

Settings for eth0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised auto-negotiation: Yes
Speed: 100Mb/s
Duplex: Full
Port: Twisted Pair
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbg
Wake-on: g
Current message level: 0x00000033 (51)
Link detected: yesHowever, if i run Fedora 9 at my desktop, i have full speed (~7 Mbyte / Second).

What can possibly cause this problem?

Thanks in advance!


November 9th, 2008, 10:25 PM

Are you going through an older HUB that is only 10mb?

If you only have two computers connected together are you using a crossover type of cable and not a regular LAN cable?
(May no longer be applicable these days?)

Do you have a really LONG LAN cable and have it coiled up on itself?

That's all I can think of right now as far as oddities that cause quirks.


November 10th, 2008, 07:02 AM
Thanks for your reply Kellemora,

I have a 100MBps router and two computers with 100Mbps NIC's, and good cables less than 10 feet, that's all.

When i run iperf between the machines i get this:

mike@ubuntu:~$ iperf -c fedoraserver
Client connecting to fedoraserver, TCP port 5001
TCP window size: 16.0 KByte (default)
[ 3] local port 35512 connected with port 5001
[ 3] 0.0-10.0 sec 113 MBytes 94.8 Mbits/sec
and the other way this:

[mike@fedoraserver ~]$ iperf -c ubuntu
Client connecting to ubuntu, TCP port 5001
TCP window size: 16.0 KByte (default)
[ 3] local port 32901 connected with port 5001
[ 3] 0.0-10.0 sec 103 MBytes 86.7 Mbits/sec

I don't understand way it's not the same speed both ways.

But never the less, the speed when copying files seems way to slow at my Ubuntu desktop compared to the Fedora 9 Desktop. It's exaclty the same hardware (dual boot on my desktop).

This has got something to do with Ubuntu.

Any more ideas are most welcome!


November 14th, 2008, 05:53 AM

November 14th, 2008, 06:21 AM
It sounds like a driver issue. What is the card? What driver/version is Fedora 9 using and driver/version is 8.04 using?

The Cog
November 14th, 2008, 12:05 PM
Can you check that both Fedora and Ubuntu are using the same Ethernet configuration? - what does ethtool eth0 say on Fedora? I am wondering if you have an issue between full and half duplex. Which is the switch configured for?

November 20th, 2008, 06:50 AM
Problem solved. After close inspection of the cable between the server and the router, it turned out to be a tiny piece of hair stuck in the cable contact surface on one of the poles. Even closer inspection revealed that it was in fact my girlfriends fault :)

Why this affected Ubuntu and not Fedora is beyond me...

Anyway, thanks for all your help.