Situation
The client has some issue with network traffics and the users complain about slow network access.
Troubleshooting
Using Fluke OptiView, we found one of servers uses most utilization on their core switch. The Out Utilization (% of Bandwidth) is Current 75%, Avg 57.5% Max 82.7% as shown.
I also found the OptiView showed the port is connecting to 10Mbps event the server NIC is 1GB. After do more testing, we found the problem is the bad cable. After changing another cable, it runs as 1GB speed and the Utilization drops to around 1%.