Linksys AG241 – QoS issue

Linksys have done a nice job with the AG241 I’ve been running it in a non-NAT mode for a few months now and so far it’s performed very reliably. The only thing that prevents it from exactly meeting my needs is the rather crappy QoS support it has.

The WRT54G and WRT54GS models include QoS based on source MAC and physical port number when running standard firmware. Upgrade this to something like DD-WRT firmware and QoS can also be based on IP and Subnet numbers. On the AG241, the only criteria is 3 IP port numbers. This is useless for my needs where I’m trying to assign low priority to kids using Webcams under MSN Messenger which seems to use vast swathes of IP ports.

Something else that’s interesting to me is the help text for QoS on the AG241.

Application-based QoS manages information as it is transmitted and received. Depending on the settings of the QoS screen, this feature will assign information a high (traffic on this queue shares 60% of the total bandwidth), medium (traffic on this queue shares 18% of the total bandwidth), or low priority (traffic on this queue shares 1% of the total bandwidth) for the five preset applications and three additional applications that you specify.

This doesn’t sound like proper QoS to me. I don’t want to restrict something to 1% of my bandwidth if nothing else is using it at the time. I get the feeling that Linksys have done a bodge here and haven’t really implemented QoS at all.

My networking skills are probably better than average and I currently can’t think of a workaround to this problem. My ADSL router is the only point on the network where I can effectively implement QoS. All the WRT54GS’s I have don’t help at all as they cannot sit between my LAN and the Internet. I thought about hanging a WRT54GS straight off the back of my AG241 to create an empty DMZ. This way I could do the QoS on the WRT54GS but unfortunately my DMZ would need a non-private IP subnet (my internal LAN is not NAT’ed, it has real addresses).

1 comment

  1. I think that 1% means that your low priority stuff is guaranteed 1% of the bandwidth even if lots of high priority stuff is going on. They can use all available bandwidth, but are guaranteed at least 1% If nothing else is using the connection the low priority apps get 100%. It’s easy to test. Just set your p2p or other bandwidth hogs to low priority and see what happens.

    Set your upload and download speeds to 90% of conservative values, ie. use the speed that a broadband speed test gives you, not what your isp says you have. This won’t effect your bandwidth, they are just figures that QoS needs to calculate how much guaranteed bandwidth everybody gets.

    If it turns out that it’s the way you describe it, it’s not really traffic shaping at all, but I think that the issue here is that Linksys is not know for their QoD (Quality of documentation).

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