Throughput Issues

Unanswered Question
Jan 3rd, 2008

I'm experiencing a throughput issue on my LAN. I'm running a 3500 series XL (100mb)switch in our admin building where the users have been reporting a lot of sluggishness and hangups on the systems while performing a RDC connection to one of our production servers.

I did some throughput testing with two identical laptops connected to the 3500 series switch and got speeds between 35 and 45 mbps.

I have a replacement 3560G switch that configured and all ports are on auto detect for speed and duplex. Presently it is a standalone switch not connected to the LAN. When I connect the two laptops to the 3560G and run the throughput test I receive to vastly different but consistent speeds. The first speed is approx 45mbps and the other is 100mbps.

Both laptops have the same 10/100/1000 NIC and the same updated driver. I have changed the speed and duplex on the laptops and switch to 100 full duplex and receive speeds of 45mbps and 90mbps.

When I switch them back to auto detect I get the original throughput speeds again. I even tried another laptop that is also configured the same and I get the same throughput speeds.

Is there a setting or something else that I'm overlooking?

I have this problem too.
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glen.grant Thu, 01/03/2008 - 17:33

No there shouldn't be . You have to make sure both ends of the link match for settings . If your nic card is hardcoded for 100/full then the corresponding switchport must be hardcoded the same also . If the switchport is set as auto/auto then the pc nic must also be auto/auto , any other combination could give a speed/duplex mismatch and slow response and errors. When you plug the laptops in on the 3560 see how they negotiated the port speed with a "show interface status command . This will tell you if they negotiated 1000 or 100 meg speeds .If you are attempting gig I would leave the ports and nics as auto . My guess is they are not negotiating gig speeds . To get gig speeds you need a good cat 5 or better patch cords with 4 good pairs as gig uses all 8 wires for data transport. In your current setup check the server ports for errors . You can use either the show interface command or the show controllers command.

munawar.zeeshan Fri, 01/04/2008 - 07:05

By the way mlowen, how much through put you are expecting ?

I also want to check my through put between my 2 7206 FE's, connected via E1. I want to check weather i am getting the promised throughput from the service provider of 2 MB.

Need guidance.


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