DGN2200 QoS is completely useless

I bought the DGN2200 because I wanted a router with QoS. QoS is supposed to prioritse traffic based on various criteria, so the connection can remain usable under heavy load. For what it’s worth, Windows’s network scheduler seems to shape the traffic very slightly such that it’s pretty difficult to kill a connection with a Windows box, but if you’ve ever had someone else in your house decide to download 300MB of Ubuntu updates, you’ll generally find you’ve got 100% packet loss until they’re done. QoS is supposed to fix that.

But I wasn’t entirely convinced that it was doing anything. Browsing while downloading was still sluggish and my TF2 pings were still jumping whenever anyone else started browsing.

So I set QoS rules:
ICMP (ping) protocol with priority “highest”
BitTorrent protocol with priority “low”,

and started a BitTorrent download. The upload speed during the download was basically negligible, and the download speed was roughly 200KB/s (my connection maxes about 240 – yes I do live in the stone age, and yes I will accept donations). Here are my pings to bbc.co.uk:

Pings (all units are milliseconds)
Min Avg Max
Without BitTorrent 31.015 31.305 31.846
With BitTorrent and QoS1 159.724 160.755 161.787
With BitTorrent and no QoS2 84.846 135.555 172.994

1. 50% packet loss
2. 25% packet loss

If the QoS is any good, the second line should be similar to the first line, and certainly closer to the first line than the third. Which it is not. The stats are better without QoS, but I suspect you’ll find that’s just because of the slightly variable nature of BT downloads, and I also suspect that in reality, if you could be bothered to collect and analyse a lot of data, you’d find the difference between the two statistically insignificant. I’m only using 4 packets so the packet loss isn’t too precise, but the fact it’s happening at all is important. I’m not seeing any compelling argument that the DGN2200 actually performs QoS.

I don’t know how Neatgear has made this so difficult. It runs the Linux kernel and good QoS tools for Linux already exist, like Wondershaper. Why didn’t they just compile it into the firmware?

I’m not doing very well with this stuff, to be honest. Amazon refunded my ATi card quite happily though, so looks like this will be going back too. I’ve since ordered a GTX560, but I’m not sure what (if anything) I’ll order to replace the router.


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