Hello,
Doing reliable performance tests is not that trivial. Your own laptops may be the bottlenecks. I would first suggest to connect them together back-to-back using a crossover cable with no switch inbetween, and make sure you can repeatedly and sustainably get a high performance out of the testing setup you're using. Keep in mind that to test 1Gbps link close to its limits (125 MByte/s), the hard drives on both laptops would need to provide a sustained read/write performance of at least 100 MByte/s. This may not always be the case with ordinary laptop hard drives. Using RAM-emulated disks (and having enough memory to prevent swapping which would revert to the performance limits imposed by hard drives) is highly recommended. In addition, the operating system should be running as few processes as possible, and ideally, the server and client processes should be running with elevated scheduling priorities. Can you confirm that with these two laptops connected via a direct cross cable, you are repeatedly and sustainably getting transmission speeds close to 1Gbps?
Plain Layer2 switching is never handled by the CPU in switches, therefore, if you are testing the throughput in a single VLAN, the CPU load is irrelevant - and even then, you have indicated yourself it is negligible.
Best regards,
Peter
