QoS setup with Draytek 2920n router using DSCP packet header for low priority backup traffic.

In short

I spent far too long figuring out how to do this not share it. Running an online backup service (Crashplan) on my laptop was killing my network for everything else that was using it. I documented in a previous post how to set DSCP packet headers on Windows 7 for Crashplan. This post is about the next step of doing something actually useful in the router.

The results

…speak for themselves:

  • No network traffic, standard config:
    Ping : 17-19ms, Jitter : 3-6ms
  • Active backup, standard config:
    Ping : 111-329ms , Jitter : 47-68ms
  • Active backup, QoS config:
    Ping : 26ms, Jitter 4-5ms

QoS setup

This video shows how I setup my Win7 pc running Crashplan online backup to set DSCP in the packet headers for upload traffic. It then shows setting up the Draytek 2920n QoS feature so that the tagged DSCP traffic tagged AF11 (decimal 10)  is dramatically reduced by up to 97% when any other traffic requires the bandwidth.

In the video I run a couple of network benchmarks using Speedtest.net and Pingtest.net before repeating the tests with Crashplan online backup running on a default config. This shows the significant impact on ping times. After the packet headers are set using gpedit.msc the router QoS is configured to de-prioritize this traffic down to just 3% of the available bandwith. The tests are then repeated with an active backup running.

I found that it easier to de-prioritize traffic that isn’t important rather than try to prioritize traffic that is.

See the video for all the steps involved. Best viewed full-screen in HD.

NOTE: Click through to the native youtube page for video timings if you want to just straight in.



5 thoughts on “QoS setup with Draytek 2920n router using DSCP packet header for low priority backup traffic.

  1. David

    Excellent post. Crash Plan is a great service but it always seems to stifle my connection at the most inopportune times. Applying similar QoS settings on my Tomato flashed router looks like it will seriously help connectivity.

  2. Raf

    Thanks for sharing Paul!
    Definitely useful.
    May I ask you what software did you use to produce this video? I like the zooms and the highlights.

  3. James

    You can mark the packets from within the Crashplan interface –

    Go to Settings – Network

    At the bottom of the window is the option to set a packet mark for the WAN and LAN.
    The bottom option in the drop down is DSCP…. Select that and then it will ask you to enter a custom DSCP value. Set it to 10 as in the video. Then go back to the drop down and you should be able to see DSCP-10 as an option in both LAN and WAN.

    1. Paul Post author

      James – that feature used to have no effect at all on Windows 7. Apparently it worked under Linux.


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