Settings for testing VSAT internet connection

Started by Mark


Settings for testing VSAT internet connection   06 March 2018, 13:29


I am currently testing network speeds and want to verify that I am using the correct settings and getting expected outcomes. I am testing for VSAT internet connection with speeds from 1Mbps to 4Mpbs and latencies 50ms-750ms.

I used the following settings on the emulator:
  • I used Wi-Fi connection and then set the speed from 1Mbps to 4Mbps.
  • I then set the latency for 50ms, 750ms for each speed.
  • I also had packet loss enabled during the test with 0.1% packets.

My results are showing that with 1Mbps and 750ms latency compared to 4Mbps and 750ms latency has almost no difference in time. Would this be a reasonable expectation? Would using an Ethernet connection make a difference in time?

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Re: Settings for testing VSAT internet connection   06 March 2018, 13:34

Yes, that's a reasonable expectation, as there is a relationship between Bandwidth-delay Product and TCP buffer size. You can check this article on the topic: How to Calculate TCP throughput for long distance WAN links.

For a standard 64K TCP window it would be: (64K * 8) bits / 0.75 seconds = 699040 bits/sec = 0.7 Mbps.

So with this latency the maximum achievable throughput is less than either limit (1 Mbps or 4 Mbps) and that's why there is no difference in time.

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