[WLC/WLA] Calculating rfping output on WLC controllers

RTT and rfping can be used to troubleshoot the following symptoms:

Intermittent wireless connection
Latency in the wireless network
Slow wireless connection

Packet round trip time (RTT) is calculated in the following way:

For the first packet, the round trip time is the time of ACK reception minus the time that the packet was enqueued.
For the second and subsequent packets, RTT is the time of ACK reception of the current frame minus the time of ACK reception for the previous frame.
Because all the packets are enqueued at the same time, it is not possible to compute RTT from the packet-enqueue time for any packets other than the first packet.

For example:

WLC2800# rfping mac 64:27:37:aa:94:21 RF-Link Test to 64:27:37:aa:94:21 Session-Id: 119 Packets Sent Packets Rcvd RSSI SNR RTT (micro-secs) ------------ ------------ ------- ----- ---------------- 20 20 -42 52 241

From the above “rfping” output:

Note that 20 ping packets were sent.
Now check whether 20 acknowledgement (ACK) receptions were received for these packets.

RTT is calculated based on the reception time of ACK of the ping packets. The overall average RTT of these 20 ping packets is shown in the rfping command output in WLC.

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