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DHCP lease problem: Renew every 30min for 60min lease?

Discussion in 'Tomato Firmware' started by gijs73, Aug 10, 2010.

  1. gijs73

    gijs73 Networkin' Nut Member

    Hello! I have an issue with the 1.28 tomato firmware that i hope you guys can help me solve.

    Even though the lease time is 3600 seconds (60min) for my DHCP connection, tomato renews every 1800 seconds (30min). According to my ISP this is considered abusive behaviour by the DHCP server and I get routinely blocked for hours without any internet connection because DHCP server over at my ISP stops responding to my requests.

    Is there any way to configure udhcpc to not renew after 30 minutes but say, 55 minutes? Leases are usually given in just a few seconds so there's no need to renew them very 30 minutes early!

    Thanks!

    Edit: Here's a typical log file:
    Code:
    Aug 10 02:22:17 router daemon.info udhcpc[289]: Sending renew...
    Aug 10 02:22:17 router daemon.info udhcpc[289]: Lease of 85.225.146.XXX obtained, lease time 3600
    ...
    Aug 10 02:52:17 router daemon.info udhcpc[289]: Sending renew...
    Aug 10 02:52:18 router daemon.info udhcpc[289]: Lease of 85.225.146.XXX obtained, lease time 3600
    
     
  2. myersw

    myersw Network Guru Member

    That would be normal dhcp behavior. The dhcp client, your router in this case, will request a renewal at aproximately 50% of the total lease time. Which would be 1800 seconds or 30 minutes. This is by the RFC for DHCP. The lease time should be coming from the dhcp server, your ISP, so if the lease time is 60 minutes that is what was provided by the dhcp server, unless there is something hinky going on here, and by the RFC the dhcp client will request a renewal at 30 minutes.
    --bill
     
  3. gijs73

    gijs73 Networkin' Nut Member

    Thank you for your reply. They do not seem to be honoring the RFC specs then, because they said I'm flooding their server. Is there any way to reconfigure this behavior?
     
  4. myersw

    myersw Network Guru Member

    Behavior is on their side. It is the DHCP server that provides the lease information. Just like on the router you can set the lease time for your computer's IP address (the 192.168.x.x addresses) lease time. This lease time normally set to one day, 1440 minutes or 86400 seconds. This is not the same as the lease time for your WAN connection to the ISP.
    Only other thing is something weird going on with your router where it is not handling the lease info correctly. I guess what I would do just to rule things out, would be to reset the router to defaults. Then do the configuration over and see if that makes any difference. Also reset the modem just to make sure we are starting from scratch.
    --bill
     

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