R650 speed test: speedflex get a low downlink speed.

yuqing

I use speedflex to test my ap, uplink speed is more than 1000Mbps, but downlink speed is less than 200Mbps, what is the reason? should I use another speed test tool?

AshwinM

Hi Yuqing,

Hope you are doing great!

Asymmetric speeds in SpeedFlex tests on our AP's, with uplink speed 1000 Mbps but low downlink <200 Mbps, are common and often not a problem.The difference between the uplink speed (more than 1000 Mbps) and the downlink speed (less than 200 Mbps) seen during the SpeedFlex test can happen for several reasons.

Possible Causes:

• Link Speed Mismatch:
  If the Access Point is connected to a 1000 Mbps switch port and the ZoneDirector/SZ is connected to a 100 Mbps port, the AP may send traffic faster than the ZD can handle. This can overload the ZD and prevent it from sending control information back to the system running the SpeedFlex test, resulting in lower downlink speeds.
• Control Frame Limitations:
  SpeedFlex depends on control frames to measure performance. If these control frames do not reach the testing system properly, the results may be inaccurate and show reduced downlink speed.
• Hardware Limitations:
  Older AP or controller models may have lower processing power. This can affect SpeedFlex performance and limit the achievable downlink speed.

Recommendations:

• Verify Port Speeds:
  Please ensure that both the AP and the controller are connected to switch ports running at the same speed, preferably 1000 Mbps.
• Use the ZAP Utility:
  You can use the ZAP utility to test throughput more accurately. It is recommended to set the test speed slightly below the lowest link speed between the AP and controller. For example, if the lowest speed is 100 Mbps, you can test at 90 Mbps using the command below:

zap.exe -r90 -s [source IP] -d [destination IP]

Replace the source and destination IP addresses with the IP's of the controller and AP.

• Use Alternative Testing Tools:
  While SpeedFlex is useful for basic validation, tools such as iPerf or ZAP can provide more detailed performance insights and help identify network bottlenecks.

Regards,
Ashwin Mathiyazhagan