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Traffic Shaping - Check My Math

SophosXGFTW

I'm using Sophos XG software on SFOS 18.0.0 GA-Build354 and have a 400Mbps broadband connection.

speedtest.net and verizon.com/speedtest show ~ 450Mbps down.

 

1) Under Configure > System Services > Traffic Shaping Settings I enter my total available bandwidth as 58000 KB/s.

2) Under Configure > System Services > Traffic Shaping I create a rule for my test system to guarantee at highest priority 12500-2560000 KB/s.

speedtest.net and VZW now show 241Mbps down.

 

If I go back to 1) and update available bandwidth to 100000 and speedtest again, I see downloads in the 450Mbps range again.

I am using an online calculator to go between Mbps (speedtest) and KBps (Sophos).

 

What am I missing here?

I need to limit / guarantee bandwidth - it seems like this should be straight forward.

(side note: Is this why the Control Center charts seem to always show an odd number for throughput on the interfaces?)



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  • 0 in reply to Keyur

    Thanks for the response, Keyur, but that article does not address my question which is:

    Why does the math not work when applying traffic shaping?

     

    If I'm correctly applying limits in KBps then the client / application should see that same limit reflected whether it's reported in Kbps, Mbps, Gbps, etc.

    Instead, the math does NOT work, and my limit in correctly calculated KBps produces a significantly slower result for the client / application regardless of unit reported.

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  • +1 in reply to SophosXGFTW

    I also noticed that the behaviour/calculation in one of the last two GA builds must have changed.

    When using GA build 354 you have to enter a value which is twice the bandwidth you have. The QoS only allows half of the bandwidth afterwards.

    If you enter 58000KB/s you will get around the half of your 450Mbps --> roughly around 225Mbps.

    Basically this is what is documented by Sophos, but in earlier builds it was possible to use it with unsymmetrical WAN connections as well. (this is discussed in many threads)

    Example before: 100Mbps down + 10Mbps up = 14080KB/s should be entered to reach full bandwidth down

    Example with GA 354: 100Mbps down * 2 = 25600KB/s should be entered to reach full bandwidth down

     

    Additionally there is the problem that the WAN bandwidth is applied to user-created non-WAN zones as well, so that internal traffic is limited as well.

    My solution on this is right now:

    I entered a WAN bandwidth of 262144KB/s which means 1Gbit/s representing my full-duplex physical connection speed of the network interface.

    My traffic shaping rules on top of this are user based guarantee rules. -> As a home user with very rare bandwidth peaks this is working without problems so far.

  • 0 in reply to Dom Nik

    Thank you!

    I'll test, adjust accordingly, and watch for bug fixes in future releases.