Slow network + collisions on hub

breakerfall · 12-28-2003, 07:33 AM

Hi

This is my basic setup:

Cable modem going to Linksys BEFSR11 router which has a 5 port hub connected. 3 Computers are connected to the hub but usually only 2 machines on at a time.

My problem is that the network speeds are too slow. They should be running at 10mbit (limited to that by the hub) however the speeds are slower than my internet connection (1mbit). I've had this issue since using linux. Whilst transferring files between computers I also see collisions no my hub (which obviuosly account for the speed decrease) however, I am not certain on how to fix the issue. Are there tweaks I can make to the connections in linux.

I believe it's linux because I have never had this problem in the past with windows machines and I would like to fix the problem. I use linux on my 2 machines and I need a decent and reliable connection between them.

Any ideas or do I just need to go treat myself to a much needed switch?

Thanks

[edit]
Running ifconfig eth0 shows an error, although I don't know whether this would cause the problems I've been having:

Code:

eth0      Link encap:Ethernet  HWaddr 00:20:ED:48:07:72
          inet addr:192.168.1.100  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST NOTRAILERS RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:30474 errors:556 dropped:0 overruns:0 frame:0
          TX packets:34292 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:17813531 (16.9 Mb)  TX bytes:4284342 (4.0 Mb)
          Interrupt:18 Base address:0x8000

quest4knowledge · 12-28-2003, 03:10 PM

This is odd, you should see an increase in speed if any change at all due to the fact that linux is a network OS.

So I have a few questions.

1. What linux distro?
2. What nics?
3. How do you obtain IPs? DHCP? ISP or Router?
4. How are you transfering the files?

breakerfall · 12-28-2003, 03:53 PM

Thanks for the reply.

1. Gentoo 1.4 final release running Kernel 2.6 final (same issue with kernel 2.4.xx).
2. One machine has an nforce NIC and the other contains a Realtek 81xx
3. DHCP / Router allocates each machine an IP (connected to the router through the hub).
4. Had the same issues with Samba, FTP, HTTP download from apache server on the box

The thing is that my friend has pretty much an identicle setup with the same NICs and very similar hardware, even running gentoo

and he has no problems. The only difference is that he is using a new switch where I am using a 4 year old hub. Is there anything I can try before having to purchase a switch?

Again, thanks for your reply.

dubman · 12-28-2003, 04:04 PM

The hub would explain the collisions you are getting. A hub is half duplex and a single broadcast domain, so a hub will inherently be slower than a switch. but with only 3 clients on your network it should not be that big a deal. I also noticed you are getting errors. Try checking ethtool and find out what errors you are getting. If you are just getting frags thats fine, this is excepted in a half duplex (hub) environment. If you are getting CRCs or alignments I would say it’s a driver problem, or the HUB itself. The hub could very well be puking garbage on the wire.

quest4knowledge · 12-28-2003, 04:14 PM

Thats a very similar setup compared to mine. Those errors on eth0 are concerning, have you tried different cat5 and/or ports on the hub. Could be faulty hardware?

You said that it started when you swithed to linux right? Do you still have windows on your machines? If so, do the speeds increase when you are in windows now?

breakerfall · 12-28-2003, 04:35 PM

Thank for the replies guys

Indeed, my speeds were faster through windows when I had that. Changing the cabling wouldn't be a task for the lighthearted. I live in the attick and we pretty much wired up the whole house with 1 of the machines being on the ground floor. I never used to have collisions at all.

Excuse my ignorance, but I have never used ethtool before, however I have just installed it and ran ethtool eth0 and this is the output:

Code:

Settings for eth0:
        Supported ports: [ TP MII ]
        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: No
        Speed: 10Mb/s
        Duplex: Full
        Port: MII
        PHYAD: 32
        Transceiver: internal
        Auto-negotiation: off
        Supports Wake-on: pumbg
        Wake-on: d
        Current message level: 0xffffffff (-1)
        Link detected: yes

I'm not sure how to do any testing with ethtool but the sections that I have highlighted above show the NIC set in full duplex mode. Also, (I'm not a network buff, yet

) but would auto-negotiation be worth having on. I presume by the name that it would work in conjuction with listening and choose when to send packets therefore having no collisions (I'm probably waaaaaaaay off on this one though... but I'd be happy if someone wanted to clue me in).

Up to know, it's starting to sound like the problem may lie with the hub.... oh the joys of spending money

dubman · 12-28-2003, 05:10 PM

Actually, that very well could be the issue. You could be trying to connect to a 10/half hub at 10/full.

try this command:
#ethtool -s eth0 speed 10 duplex half
(little "s")

or

#ethtool -s eth0 autoneg on
(little "s")

also, to get packet stats (CRCs, Alignments, etc) try this command:
#ethtool -S eth0
(big "S")

breakerfall · 12-28-2003, 07:51 PM

Quote:

Originally posted by dubman
try this command:
#ethtool -s eth0 speed 10 duplex half
(little "s")

also, to get packet stats (CRCs, Alignments, etc) try this command:
#ethtool -S eth0
(big "S") [/B]

Done

The output of that last one:

Code:

NIC statistics:
     early_rx: 0
     tx_buf_mapped: 0
     tx_timeouts: 0
     rx_lost_in_ring: 0

Well I just ran that command and I now get much better speeds... thanks

One problem, on the nforce system, I can't use ethtool. It can't pickup any information at all. It's very strange. I still think I would be better off getting a switch now anyway so i can use the full 100mbit speed

I'm guessing I would just do: ethtool -s eth0 speed 100 duplex full to get things back to 100 full duplex?

Thanks for your help

chort · 12-28-2003, 09:25 PM

Check the documentation of the nForce drivers (you can get that on nVidia's site. They have special arguments for modules.conf that will set the duplex and speed.

breakerfall · 12-28-2003, 09:40 PM

Thanks for that

I don't think I really need to look into it. I'm going to purchase a new 10/100 switch tomorrow. It's about time I got one

Thanks for all the replies: always appreciated.