Changing WAN Settings when DHCP Lease renews



  • Hey everyone.

    I have what seems to be an interesting situations on my hands. The router that I have at home is a Motorola NVG510 that is provided for my AT&T DSL service. Here is a link to the "accepted" setup procedures: http://forums.att.com/t5/Features-and-How-To/NVG510-Bridge-Mode/td-p/2890841#messageview_12.

    Here is the interesting bit:

    Theoretically, the NVG510 should, using its own DHCP, give the AEBS its own public IP address (the "Broadband IPv4 Address"), a valid Subnet Mask, and the Default Gateway (Router) value equal to the "Gateway IPv4 Address".

    In actuality, for some reason, the NVG510 only will give the AEBS its Gateway  and DNS values. The AEBS gets an internal IP address and a Subnet Mask of 255.255.255.255. I suspect a bug, er, "feature", in the NVG510's firmware…

    The Actual Setup
    The fix, then, is to set everything up as described above - except... in the AEBS, I changed the last step:

    • Under Internet, TCP/IP,
      Configure IPv4: Manually
      IP Address: <the rg's="" "broadband="" ipv4="" address"="">Subnet Mask: 255.255.0.0 (Note that I'm not certain this is correct. The NVG510 doesn't show a subnet mask on its Broadband/Status tab, but the values I have showing would work with this mask.)
      Router: <the rg's="" "gateway="" ipv4="" address"="">DNS:<the rg's="" "local"="" ip="" address="" (e.g.,="" 192.168.1.254="" by="" default)=""></the></the></the>

    The short version is this: whenever I get the lease from the modem, I need to change the lease by setting the correct subnet mask (and gateway) on my WAN interface, otherwise it doesn't work.

    Is there a hook or script that will allow me to do this? If so, which one? Or do I just need to come up with some other solution to handle this? One feature that this modem has is the capability to setup a "cascaded" router, but I can't find anything that talks about how this works, just that it is supposed to allow having another router behind this router. Seems hackish, but I've been out of Ops for a while and maybe it's what all the cool kids are doing nowadays (that and creating poor routers).

    If I'm doing something wrong here or there is a better way, please let me know!