Flow Monitor Question - min time?

[Ella Robinson]

Is there a minimum time for flow monitor to operate?
When I run my simulation for 30 seconds, the lost packets in flow monitor are being displayed correctly as tx packets - rx packets.
However, when I run the simulation for 10 seconds, the lost packets are always 0, although I can see that packets are being lost.
Is there a minimum time for flow monitor to operate?
My network is not congested.

For 30 s:
Flow ID: 1 ; 10.1.1.2 ----> 10.1.1.1
  Tx Packets: 2849
  Rx Packets: 2849
  Lost Packets: 0
  Throughput: 94.9667 Kbps
Flow ID: 2 ; 10.1.1.3 ----> 10.1.1.1
  Tx Packets: 23749
  Rx Packets: 23736
  Lost Packets: 13
  Throughput: 791.2 Kbps
Flow ID: 3 ; 10.1.1.4 ----> 10.1.1.1
  Tx Packets: 23749
  Rx Packets: 23748
  Lost Packets: 0
  Throughput: 791.6 Kbps
Flow ID: 4 ; 10.1.1.5 ----> 10.1.1.1
  Tx Packets: 23749
  Rx Packets: 23741
  Lost Packets: 8
  Throughput: 791.367 Kbps

For 10 s:
Flow ID: 1 ; 10.1.1.2 ----> 10.1.1.1
  Tx Packets: 849
  Rx Packets: 849
  Lost Packets: 0
  Throughput: 84.9 Kbps
Flow ID: 2 ; 10.1.1.3 ----> 10.1.1.1
  Tx Packets: 7062
  Rx Packets: 7048
  Lost Packets: 0
  Throughput: 704.8 Kbps
Flow ID: 3 ; 10.1.1.4 ----> 10.1.1.1
  Tx Packets: 7062
  Rx Packets: 7062
  Lost Packets: 0
  Throughput: 706.2 Kbps
Flow ID: 4 ; 10.1.1.5 ----> 10.1.1.1
  Tx Packets: 7062
  Rx Packets: 7054
  Lost Packets: 0
  Throughput: 705.4 Kbps

[Gabriel Ferreira]

It is a fun thing that you said 10 seconds. Because that is precisely the default value for MaxPerHopDelay of FlowMonitor.
a.k.a. it considers these packets are still in flight (which may be correct).

[Ella Robinson]

Got it, thanks Gabriel!

I am observing another thing. For each flow, the first 3 packets are received fine, but then I experience a burst of drops. And then all is good for the rest of the simulation.

I have tried changing traffic models, tweaking with the start times of apps, but I am getting a consistent trend. 

First 3 packets get out and reach receiver fine, then a burst of consecutive packet drops, and all good for the remainder of the simulation.

It's a simple Wi-Fi network. 1 AP, 3 STAs. Uplink only. STAs using OnOff application to generate packets and sending to AP. AP has packet sinks installed.

Any clue as to why this could be happening?