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slow throughput

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slow throughput - 19.Dec.2004 11:55:00 PM   


Posts: 12
Joined: 13.Dec.2004
Status: offline
It's a well known fact that there is no bandwidth limiting in ISA 2004, my internet connection is only 3Mb/sec into the server, server runs at 2-4% cpu, and roughly 50% utilization on ram(512)...

But I am only able to get 220-240Kb/sec though my ISA server from the internet connection? I replaced the bridge(aka modem) that it was hooking into for my DSL line with one that I knew could handle the throughput, thinking the old one was above capacity, and did a quick test with a XP box plugged straight into it, with a Public IP, and I was able to get the expected 340Kb/sec.

I then plugged in the ISA server again, plugged the same XP machine back into the network, and I'm only getting 220-240Kb/sec again (I'm pulling off one my servers with a 10Mb/Sec pipe and I know it's not even at 5% currently so it's not a problem on that end)

I then went to the ISA server, and tried to pull the same file down from the same server, and was able to get the same 220-240Kb/sec throughput...

Ideas on where I'm loosing 100Kb/sec of bandwidth??
Post #: 1
RE: slow throughput - 20.Dec.2004 10:57:00 AM   


Posts: 50013
Joined: 10.Jan.2001
From: Texas
Status: offline
Hi Accent,

Sounds like a hardware problem on the ISA firewall.


(in reply to accentconsulting)
Post #: 2
RE: slow throughput - 28.Dec.2004 9:13:00 PM   


Posts: 12
Joined: 13.Dec.2004
Status: offline
doubtfull, the server is a brand new dell less then 60 days old...

(in reply to accentconsulting)
Post #: 3
RE: slow throughput - 28.Dec.2004 10:09:00 PM   


Posts: 115
Joined: 27.Jun.2004
Status: offline
This is what a some suggested in another form I did not try it yet be you can see if it well help you out

ISA Server 2004 sets the registry key EnablePMTUDetection to 0 upon installation which effectively makes the MTU 576 for outbound requests. This registry modification is in compliance with 324270 How To Harden the TCP/IP Stack Against Denial of Service Attacks in Windows Server 2003

Take a trace on the external NIC during the testing and see what the MTU is - it should be 576.

To change this, go into the registry and under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters, change the registry value for EnablePMTUDetection to 1 and reboot. Test again and see if the performance changes. You should see a significant improvement

(in reply to accentconsulting)
Post #: 4

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