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Micro outage when DHCP renews (Tomato 1.27)

Discussion in 'Tomato Firmware' started by Ragnor, Dec 26, 2009.

  1. Ragnor

    Ragnor Addicted to LI Member

    I recently upgraded the firmware on my Linksys WRT54GL v1.1 to Tomato v1.27 (was v1.21). The WAN IP address is set to "obtain automatically", the device that it gets its WAN IP address from has a short lease (60min) so when the external ip changes it's picked up relatively quickly. Note: This is a pppoa half bridge situation (pppoe is not available).

    However I have noticed that when the external/wan ip address has not changed and the DHCP lease ticks over there is a 20ms freeze or lag. It's particularly noticeable when gaming (Left 4 Dead 2 for example). I never noticed this problem in Tomato v1.21 or earlier.

    I set a couple of repeating pings up. The WRT54GL continues to respond to pings normally at <1ms on it's LAN IP address but the device on the WAN side of the WRT has a 20ms delay right at the every 60min mark.

    Has anyone else seen this behaviour?
  2. Ragnor

    Ragnor Addicted to LI Member

    Actually this seems to be easily repeatable.. example:

    Address of the WRT54GL running tomato:
    Address of the modem wan side of the WRT:

    1: Open a cmd window and: ping -t
    2: Open a 2nd cmd window and ping -t
    3: Login to the Tomato UI and click the renew button on the status > overview > wan page will take 15-20ms to respond for several of the pings instead of <1ms will have a destination unreachable right as the renew is done instead of <1ms

    Remember this is a standard DHCP renew where nothing has changed (ie: WAN IP address). So is this expected behaviour? As mentioned I don't remember seeing this happen in v1.21, what's changed?
  3. teddy_bear

    teddy_bear Network Guru Member

    Can you run ND version on GL routers?

    If so, try my mod from this thread - there's a non-USB build which doesn't include any USB features and, from the functional standpoint, is the same as vanilla Tomato. However, I applied several DHCP-related fixes from newer Busybox code, and I hope they should solve issues like yours.
  4. Ragnor

    Ragnor Addicted to LI Member

    Thanks Teddy Bear, it's a WRT54GL v1.1. If I go to Admin > Debugging > Download NVRAM dump and search through it for corerev I find "wl0_corerev=9"

    I should be able to run the ND version on this model I think, can anyone confirm?
  5. Engineer

    Engineer Network Guru Member

    Any corerev=7 or higher should be good to go on the ND version.
  6. mstombs

    mstombs Network Guru Member

    In the Original post the lease is supposed to be 60 minutes, so it should renew cleanly at half time, if the lease times out a full restart of the WAN results. there's been a few threads about this type of problem and there's a dd-wrt firewall script patch that works for some folk.
  7. joelpt

    joelpt Guest

    Do you have a link to the script you mention? Was not able to find it with several minutes of searching around here. Thanks!

    EDIT: I think this may be the script that you are referring to: http://www.dd-wrt.com/wiki/index.php/Useful_Scripts#Automatic_Connection_Repair_.28always_on.sh.29

    I've updated to Teddy Bear's Tomato version. If that doesn't fix my problem (WAN dropping out a couple times a day) I will try the above script. Either way, I'll report back with results in a few days.
  8. mstombs

    mstombs Network Guru Member

  9. Ragnor

    Ragnor Addicted to LI Member

    Adding the extra firewall rule mentioned on the ddwrt forums didn't work for me.

    However updating to Teddy Bear's version appears to have resolved the problem, presumably it's either the newer version or busybox in his release or some of the other tweaks/fixes.

    Thanks for everyone's help.
  10. neoufo51

    neoufo51 Network Guru Member

    I had the same problem with the same router, the same firmware version, with the same online game and finding this thread and updating to the Tomato version with the new busybox also fixed my issue.
  11. Ragnor

    Ragnor Addicted to LI Member

    Thank [insert deity] for the internets!
  12. Lord KiRon

    Lord KiRon Addicted to LI Member

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