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smakme7757

Why? 1 Gigabit p/s is slower than 100mbps?

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Ok,

 

To cut a long story short, for the last 3 weeks i have been struggeling to understand why my laptop would never be able to get over a 0.5 megabit connection (on a 5mb line) to the internet when all the other machines in the house could get full speed (connected by ethernet). I formatted, changed drivers i did everything but it always failed!

 

So anyhow i noticed all the other machines connected at 100mbps and mine would connect at 1gbps. So i forced the NIC to connect at 100mbps and what do you know...it worked =D.

 

But im just wondering why, why does it work at full speed at 100mbps and slow as buggery at 1gbps?

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Gigabit networking pushes Cat5 to its limits. If your cable is shitty, it'll lose packets and give you crappy throughput, where running it at 100Mbps would otherwise work.

 

Try replacing the cable.

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A crummy switch that's no good at handling the transition from 1Gbps to 100Mbps?

No its a new D-link DIR-855 and ive managed to get full 1gb capacity on my desktop so its something wrong with my ethernet port on my laptop. But i cant be bothered sending it in for repair too much stress for little gain, i use wireless anyway.

 

But at least i know its not the new router i got lol.

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Also when it's running at 1Gbps has it autonegotiated that rate or have you forced it in the driver config?

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Did you try a different cable????

Yea i tried 3 cables, all the same result.

 

@ Segger, 1gbps was autonegotiated by the NIC. I forced it to negotiate 100mbps, at least it works at 'Full' speed at the speed!

Edited by smakme7757

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Could be some kind of an odd flow control issue and it's still possible the switch is shagged.

 

Are these cables you've purchased or made? 1000Base-T relies on all 4 pairs being wired correctly - if they're not, weird shit might happen.

 

Try running an iperf session from the suspect system running @ 1Gbps auto to another system also at 1Gbps.

Then do the same but from the suspect system @ 1Gbps auto to another system at 100Mbps (autonegotiate only - not forced).

Lastly run it from the suspect system to another system @ 1Gbps auto, directly connected to each other. (not via the switch)

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