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Network switches slow down connection

Posted on 2011-09-12
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Last Modified: 2012-05-12
Hi guys,

I'm having an issue where whenever I connect a switch between the wall and the machine, network speeds are significantly slower. It almost seems like they are reverting to 1Mbps speeds. At first I thought it was the switches themselves (they are 10/100 Netgear FS108's) but I got different ones and the result is the same. Plugging directly into the wall (and by wall I mean a bunch of Cisco Catalyst switches) works fine. I tried changing the NIC settings to auto-negotiate and 100Mbps Full Duplex, but it didn't seem to have made a difference. These are all unmanaged switches and the activity lights on them show them as being in 100Mbps mode.

Speed tests show only download speed affected. I also tried different ethernet cables.

Would anyone know why introducing the switches degrades network performance for all machines connected to that switch?
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Question by:Titlevest
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carlmd earned 300 total points
ID: 36522604
You could try manually setting the baud rate AND the duplex on both ends. If two connected switches are set to auto negotiate and get the wrong duplex setting, you can see what you are describing.
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by:pjam
ID: 36522643
Please forgive me if i misread or understand.  It sounds like you have a Netgear Hub between you and a cisco Switch.  That IMHO is never a good idea as it can cause looping.
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Author Comment

by:Titlevest
ID: 36524086
Just to clarify, the current setup is as follows:

NetGear 8 port desktop switch FS108->wall jack (patch panel->Cisco Catalyst 48-port switch)

This is the desktop switch we are using (we have multiple and all give the same result): http://www.amazon.com/NETGEAR-ProSafe-8-Port-Desktop-Switch/dp/B00002EQCS/ref=sr_1_1?ie=UTF8&qid=1315844895&sr=8-1

We bought different brands of switches to see if it was a Netgear issue but they all yield the same result. One interesting bit of information is that we tried hooking up an old D-Link 5 port switch and it worked perfectly. There were no slowdowns whatsoever.

@pjam
It's definitely a switch, not a hub.

@carlmd
I'll check it out although i'm not hopeful
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Expert Comment

by:sameer_dubey
ID: 36528706
I would test with a 8-port switch that does not support "auto uplink". Just to rule out any issue in two switches working on "auto uplink".

There may be a loose connection in your wall port (patch panel). I would check that as well.
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by:sloden94
sloden94 earned 100 total points
ID: 36529304
One thing to check would be your port configuration on the catalyst. Make sure its on auto instead of full duplex.
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by:eeRoot
eeRoot earned 100 total points
ID: 36533268
Can you check the config on the Cisco switch?  Smart switches often have settings to limit the total number of clients allowed on a port and the speed as well.
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Author Comment

by:Titlevest
ID: 36559774
@sloden94:
This is what it says on for all ports:

 speed 100
 duplex full
 spanning-tree portfast

I'll try changing it to auto and see if it makes a difference.

@eeRoot:
What would such a a limit on the number of clients show up as in the config file?
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by:eeRoot
ID: 36564760
Those would be "switchport port-security" commands.
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Author Comment

by:Titlevest
ID: 36600404
I forced 100Mbps and full duplex and that fixed it. Thank you all for your help!
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