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PPTP and QoS

Discussion in 'Tomato Firmware' started by jochen, Mar 10, 2007.

  1. jochen

    jochen LI Guru Member

    Are there any known issues with PPTP and QoS?
    When I enable QoS my PPTP connections stop after some minutes.
     
  2. roadkill

    roadkill Super Moderator Staff Member Member

    Pass Thru or Dialing to the DSL?
     
  3. jochen

    jochen LI Guru Member

    Pass Thru
     
  4. Toxic

    Toxic Administrator Staff Member

    have you tried giving higher priority qos to pptp?
     
  5. jochen

    jochen LI Guru Member

    Yes, that didn't help.
     
  6. roadkill

    roadkill Super Moderator Staff Member Member

    I think 1.05 solves your problem...
     
  7. jochen

    jochen LI Guru Member

    1.05 makes no difference. Disabling the NAT helpers also does not make a difference. PPTP does only work reliable if QoS is disabled.
     
  8. roadkill

    roadkill Super Moderator Staff Member Member

    try to classify PPTP as a high priority so QOS will not close the connection...
     
  9. jochen

    jochen LI Guru Member

    Priority is not the problem (it's set to medium), the connection stalls even if this is the only traffic through the router.
     
  10. jochen

    jochen LI Guru Member

    I think I found the cause for my problems.
    My ISP gives me a upload bandwith of 220 kbps.
    In QoS settings I have set 200 kbps.

    When my upload through PPTP reaches this threshold, packets are dropped (this is the way QoS works). It looks like PPTP cannot handle packet loss.

    When I limit bittorents upload to 10 kbyte/s, so that I never reach the 200 kbps threshold, PPTP runs well.

    But what, if I get a VoIP call (higher priorized) and PPTP packets are lost again?

    I have to limit upload bandwith through PPTP, so that there is always enough bandwith free for a VoIP call. But then I don't need QoS. :confused:
     
  11. der_Kief

    der_Kief Super Moderator Staff Member Member

    Hi,
    it seems that you set the QoS upstream to high (or is 220kbps measured speed?) ! Try the following: disable QoS, measure your real upload speed (best to start ftp upload to fast server), than enter 90% of measured upload speed and activate QoS. Here is an interesting artcile about implementing QoS.

    der_Kief
     
  12. jochen

    jochen LI Guru Member

    At the moment the measured speed ist 200 kbps. But even if I set upload in the router to 150 kbps, as soon as Bittorrent (through PPTP tunnel) comes in the near of this threshold, the PPTP connection hangs (zero throughput)
     
  13. der_Kief

    der_Kief Super Moderator Staff Member Member

    Hi,

    did this ever work for you (with Tomato) ? Maybe you should ask Jon about this !

    der_Kief
     
  14. jochen

    jochen LI Guru Member

    No. And yesterday I tried it with DD-WRT -> same problem.
    Maybe it's a problem with Linux/Ipfilter.

    Is someone familar with the GRE protocol (used by PPTP)? What happens if packet are dropped? Is it a protocol like TCP (packets are acknowledged and resent) or more like UDP (no packets resent)?
     
  15. der_Kief

    der_Kief Super Moderator Staff Member Member

    Hi,

    i dont know the GRE protocol but maybe Wikipedia has some information for you. And also this thread may have some information.

    der_Kief
     
  16. jochen

    jochen LI Guru Member

    Thank you for that link. Sounds like the same problem as mine.
     

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