RV0xx v1 DHCP lease management troubles

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by Sfor, Jun 12, 2013.

  1. Sfor

    Sfor Network Guru Member

    In general DHCP works fine on both RV042 and RV082 But in some cases an automaticaly created DHCP lease remains permanently in the router memory. If it happens the problematic DHCP lease entry does not allow to move the device to any other IP, as the static DHCP function does not work for this MAC, any more.

    In case a new lease is created, an entry appears in the DHCP - Status list. Such an entry shows host name, MAC and IP. When the IP is released the entry disappears.

    When the permanent entry phenomenon happens, every DHCP query with a certain MAC brings back an old record with stored host name. I mean, when a computer with the same MAC, but different host name requests for a DGCP lease, the entry appears with the old host name and IP, no matter what the current computer host name is. In the same time the entry in DHCP static IP is not taken into consideration. The computer with this particular MAC always gets the same old IP (even if the IP is outside of the DHCP server dynamic IP range). In the same time, DHCP leases of all other computers are working correctly.

    I tried:
    - to reboot the router
    - to release and then renew the lease
    - to delete the lease from the DHCP - Status list
    - to set a static DHCP rule
    - to change the DHCP server dynamic IP range
    - to move the saved config file to another RV042 router
    nothing seems to be working. It appears the permanent lease entry is kept in the router flash config file, and gest tranferred with it to other devices.

    I'm out of ideas at the moment. But, I refuse to just to bring the router config back to the factory settings, and then to reenter all the settings.
  2. Sfor

    Sfor Network Guru Member

    Using RV042 serial port I was able to access Open RG config file with the stored DHCP entries data. What I found was very unusual. There were stored all the old DHCP entries from different networks the router was working in. Apparently the system stores all the outdated or deleted DHCP entries permanently. I did not try to find out why the problematic entry is behawing as it does. I just deleted all the unnecesary entries including the problematic one.

    After saving the config file to the flash memory and rebooting the device, the DHCP started to work as it should to.

    Apparently it is a good idea to restore the factory defaults configuration, from time to time, as the Open RG collects DHCP garbage with time.

    Now it is the time to do the same for the RV082. But, this one does not have the serial port installed. So, I will have to try the same trick through telnet.
  3. Sfor

    Sfor Network Guru Member

    OK. I did RV082 through telnet connection using VPN tunnel. The DHCP works, as it should to, now.
  4. Sfor

    Sfor Network Guru Member

    I did encounter another DHCP problem with an RV082 v1. This time a particular computer received a different IP each time it did DHCP release and obtain procedure. To be more specific, with each obtained DHCP lease the IP grew by one. By the time I noticed this behavior, the RV082 was storing almost 70 DHCP entries with just 12 computers in the network. Luckily everything went back to normal, after deleting all the unneded DHCP entries through Telnet.
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