QoS- slow downloads? configuration problem?

Discussion in 'DD-WRT Firmware' started by anen, Jun 12, 2006.

  1. anen

    anen LI Guru Member

    I just bought a shiny new WRT54GL and am running DD-WRT firmware. I am very pleased so far, with one quirk. I set up QoS, with 2 rules, and those were putting usenet and bittorrent to bulk priority. I am running on a 15mbit downstream cable connection. Normally I can download at around 12,000-15,000k/sec. With QoS enabled, I only get about 800-900k/sec. Am I setting up something incorrectly?

    I tried to search the archives, and the best answer I could find was that there isn't enough processing power in the WRT54 to handle connections over 5mbits or so.

    Someone shed some light on this for me please.
  2. Magus255

    Magus255 Network Guru Member

    I had the same problem. It seems to be a hardware limitation.
  3. anen

    anen LI Guru Member

    If it indeed a hardware problem, what router is capable of what I'm trying to do?
  4. Toxic

    Toxic Administrator Staff Member

    Something that cost much more than a WRT54GL :) are you running the applications from the same PC or are these different from the one you want to have a main priority for?
  5. danr

    danr Network Guru Member

    How did you set up your QoS?

    Using L7 filters SLOWs things down alot as it has to inspect the contents of the packets. What did you put for your u/l / d/l bandwidth?

    Have you looked at the router status page to see how the Memory and CPU rates look? (I gather you could use 'top' if you telnet into the router as well. top is a bit resource hungry itself.)

    I've also read that the 5 MBPS limit was bogus... Although, I'm pretty sure that a 30MBPS connection is over the limit. I don't remember where I read what the real limit is (which of course would also depend upon what features you're using). I only have a 5MBPS connection, so I can't comment from experience.

  6. anen

    anen LI Guru Member

    The only options I checked in QoS were the following:
    1550kbs upload, 15000 download
    optimize for gaming

    services priority:
    bittorrent and nntp set to bulk

    I don't know how to check the memory and cpu rates. How do you do it from the GUI?

    And does anyone have suggestions as to what hardware can handle a 30mbps connection?
  7. danr

    danr Network Guru Member

    Regardless of QoS, there are a few tweaks which should be done, if you're using Bittorrent (or other P2P), as, by default, it'll cause router slowdown and crashes etc.

    These are the three most important things to change:
    Maximum Ports: 4096
    TCP Timeout (s): 90 or 120 (600 - seems safe for AIM etc)
    UDP Timeout (s): 90 or 120 (600 - seems safe for AIM etc)

    90/120 is what the WIKI says, the user groups suggest using 600 seconds, since otherwise it causes problems with some programs such as AIM. Without the port/timeout changes, if you use P2P, the router quickly runs out of available ports in the port table and starts dropping packets. 4096 is the max -- the larger the number of ports, the more memory it takes - so you may want to compromise somewhat. I have also been told (I stay away from P2P) that P2P software has settings which allow the user to tune how many connections can be used by the software.

    Back to QoS:
    The webpage with the stats is (if you have the router's
    IP set at the default):

    Optimize for gaming, optimizes for SPECIFIC games, listed here:

    You could try disabling each of the three things you have selected, to see if one specific one is causing the issue. You could try manually specifying port ranges, instead of using the L7 filters and see if that helps (if the port ranges are pretty much exclusive to the application you're using).

    You may also want to look at the syslog, to see if there is anything obviously weird there (although less likely, for a performance issue). Turn syslogd on in
    and the look in /var/log/messages .

    You may want to post your message in the official DD-WRT user groups.

    For the u/l and d/l speeds, make sure that you test your actual bandwidth (eg www.speakeasy.net/speedtest) and then take a percentage of that. For u/l, between 80-95% and for download, between 80-100%... Do some testing. At those speeds, you probably don't need much QoS for d/l altogether..

    Basically, you're purposely lowering the max speed, so that you move (part of) the buffer to your router. Once the router has the buffer, it can look at that buffer and prioritize the packets. If it has no look-ahead buffer, it doesn't have anything to look at, to make a decision to determine what to prioritize. (D/L QoS is only partially controlled --- TCP packets are controlled via controlling ACK responses.)

    (eg, If there was only one file put in an inbox, and then you received the next file after you completed the first file, you couldn't prioritize your work for the day. If you were given a bunch of files at one time, you could look at them and determing in what order to work things.)

  8. wisurf

    wisurf LI Guru Member

    QOS for VOIP

    We have a number of Linksys PAP2's connected to the WRT54GL with DD-WRT via the lan port and then Senao WiFI Access Points.

    We need to put some level of QOS/Prioritisation for our VOIP service on and I am trying to do this by using the individual Fixed IP addresses of the PAP2's and setting them to Premium.

    However, firstly (and pardon my ignorance here), the address format appears to be xxx.xxx.xxx.xxx/xxx. What is the /XXX and how significant is it ??

    We also want to block as many, if not all, of the P2P traffic on our networks. I have set the "Catch all P2P" option to on. Is this adequate or should we do more ??

    Thanks in advance !!
    Peter at Wi-Surf
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