2009/11/19

wondershaper is a real wonder

Have you ever experienced "slow internet" when there is another ongoing transfer on your wire which fully saturates the bandwidth. Even if one can accept high latency of HTTP transfers (sooner or later the page will appear in the browser), in case of interactive sessions like SSH it is completely unacceptable. Wondershaper is a great remedy with minimal side effects - especially if your are running your router on Linux machine.

Wondershaper is using CBQ instead of HTB and I am aware that there are better approaches to traffic shaping in Linux. But "traffic shaping" is usually associated with the context of splitting the bandwidth of single internet link among many hosts. This is too much in my case and wondershaper does exactly what I expect.

My ADSL line is 1024/256kb officially. But in logs I can see different values:

ATM dev 0: ADSL line is up (1312 kb/s down | 320 kb/s up)

At first I tried to provide these values to wondershaper, however they were too high (high latency still and packet drops in addition). By using different values I finally established that official numbers give the best trade-off between latency and link speed.

In case of my link the average download rate is around 126KB/s. Now with wondershaper it is around 120KB/s - about 95% of the original speed - this the cost. However SSH sessions work like a charm when updates are being downloaded and the browser loads pages almost as fast as usually.

Now specific section of my /etc/network/interfaces (Debian specific) looks like:

auto ppp0
iface ppp0 inet ppp
    pre-up /usr/local/sbin/firewall.sh start
    pre-up while ! grep 'Line up' /proc/net/atm/speedtch:0 &>/dev/null; do sleep 1; done
    post-up echo "1" >/proc/sys/net/ipv4/ip_forward
    post-up wondershaper ppp0 1024 250
    pre-down wondershaper clean ppp0
    pre-down echo "0" >/proc/sys/net/ipv4/ip_forward
    post-down /usr/local/sbin/firewall.sh stop

Update

With the 1024 256 values I still had some latency where my uplink was fully saturated. The 1024 250 values seems to work OK.

4 comments:

  1. Do you use it to divide bandwidth between computers or just to provide QoS to different services? Is there any additional config wondershape script, especially to divide bandwidth between machines?

    If you talk about synchronisation speed - it will always be higher then real speed, so you should assume you have 1024/256. And usually traffic shaper documentation advises to substract a few percent (about 5%).

    ReplyDelete
  2. I use it for QoS.

    It is just enough to do:

    apt-get install wondershaper
    wondershaper 1024 256

    Here is excerpt from documentation:
    "I attempted to create the holy grail

    * Maintain low latency for interfactive traffic at all times

    * Allow 'surfing' at reasonable speeds while up or downloading

    * Make sure uploads don't harm downloads, and the other way around

    * Have the ability to mark certain hosts/ports as 'low priority'"

    The only additional options to set are: low priority outgoing traffic, low priority destination netmasks, low priority source ports, low priority destination ports. I hope to never touch them anyway. :)

    ReplyDelete
  3. Very handy. Thanks for showing a real world example for this tool (and a recent one too!) What sparse doc I found was all pretty old, I wasn't sure how likely this was to work.

    ReplyDelete
  4. This is a very informative article.I was looking for these things and here I found it. this information is very useful me.
    Slim 24 Pro | Fair look | Zero Addiction | Air sofa | Air Bra | Step Up Height Increaser

    ReplyDelete