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Nersölat nätverk....varför???


SuperCali

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Tjena,

Här kommer en liten fråga, ursäkta att det är på eng. men det är mitt första språk och jag skriver bättre då. Det går bra att svara på sve. dock.

 

I have a network consisting of the following:

Win2k Server (as PDC), DNS, DHCP, WINS server

Win2k Pro workstation, FTP, proxy(gateway), file server

Win98 Workstation FTP server

Linux Redhat 6.1 server/wks, samba, dns server

OpenBSD bridged router firewall using ipfilter

Linux Redhat 6.1, web (apache), ftp samba server

Also some other stuff that is not relevant here.

HUB 10/100 autosensing

 

All the machines except the win2k computers are connected to a 10/100 HUB. The win2k pro is connected to the OpenBSD bridge, as it is an internet gateway, I have it on the other side of the firewall. The firewall has a back-to-back with the win2kpro and the win2kserver and the HUB. I run only tcp/ip. Here is the problem, my network is excessivly slow and I get an avergage throughput of only 400kbit even though I am running all machines on 100BaseTX!! This however only happens when the machines are connecte throught the HUB. When I run them back to back the speed is up to 6Mbit per sec, usually 2mbit. I know that a HUB slows down the connection because it is a kind of token passing and all ports share the bandwidth, but it should at least give me about 1Mbit!!!

 

There is practically only one active user on at any one time so there isn't any congestion probs. The only thing I could think of is that it might be due to the HUB not being able to handle the full duplex (the NICS are set to full) so therefore an excessifve amount of negotiation/syncing/resending occurs resulting in collisions which slow down the network!? However the collision light doesn't light up that much. Anyone have any idea if this could be the prob, or if there is some other prob?! Thankful for any help.

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Rikard Ståhl

Try to use for example Network Monitor to sniff the net. Look at the packages.

On what machine are you when it's slow?

 

best regards

 

Rikard

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Hello,

What exactly would I be looking for? The thing is that the problem isn't on any specific host but rather on all of them. I had a similar problem before with win95 and NT computers. I solved that by doing a driverupdate (3com)and winsock update for windows. I'm not 100% sure but this time around I don't think I had this problem until I reinstalled the win98 machine, removed the new install and ghosted back the old one. Also I just now tried (whilst writing this response) and the speed was significantly better now that the win98 machine isn't logged in to the domain. Could this be a problem with the tcp/ip protocols (stack) in win98? Thankful for any help.

 

// SuperCali

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Hello Again,

I have done some more testing using a network monitors and have come up with some really strange results.

 

I had only three machines plugged into my 10/100 HUB. They were configured as follows:

 

x = P2 450@504Mhz with 3com905b running full duplex, win2k pro

 

y = Pentium 200@250Mhz with 3com905b full duplex, win98

 

z = Dual pentium 166 full duplex Intel Pro 10/100, running win2k server

 

I used a 20Mb file and transferred it between tthe machines and here are the bit's per second:

 

Between machine x and y 400kb-900kb peaked a couple of times at 1.2Mb.

 

Between machine x and z 3.2-3.5Mb peaked at 3.8Mb.

 

Between z and y 800Kb-1.5Mb peaked at 2.0Mb

 

Then between y and x 140kb-200kb hit 330kb a little more towards the end peaked at 850kb breifly.

 

The source of the problem here seems quite clear, the win98 machine is causing the hassle, but why!? There aren't many collision so that is pretty much ruled out. Of course the disk in the win98 is an older model but I am sure it'll give me more than 400kb/s sustained output, so what is the prob? Any ideas would be great. The strange thing is that when my friend ghosted my hdd with win98 onto his machine he too had severe problems with his network and he is running a proper switch!!! Could it be a badly programed tcp/ip stack or what?

 

// SuperCali

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