Author Topic: Single nic with dual dhcp  (Read 984 times)

andramalech

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Single nic with dual dhcp
« on: December 04, 2007, 04:22:13 pm »
Ok here's my situation. i currently have my network setup as cable modem-wireless router running ddwrt and dhcp. I initally set up linux mce as the dhcp server and router but the problem i have is trhat if the core is down there's no internet access for my iphones or laptops, xbox ps3 generally everything. i was wondering if it would be possible to run the dhcp server on the ddwrt for 192.168.80.1-20 and have the core handling dhcp for 21 and above, this way if the core is down everything else will still have access and i hope that the core will still be able to pxe boot my thinclients in the other 3 rooms. i really dont like running seperate networks because then i would have to run 2 seperate wireless routers one to acess the internet when the core is down and the other so that i can use the web orbiter with my iphone

rrambo

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Re: Single nic with dual dhcp
« Reply #1 on: December 04, 2007, 05:23:51 pm »
I have the same setup as you do...  cable modem -> ddwrt..  one nic in my core...  here is what you need...  I'm gonna give you my ip scheme...on your ddwrt router, the internal address is (192.168.1.1).. turn off dhcp, point dhcp server to (192.168.1.2) which is the "external" address of your core (eth0)

on the core, eth0 (external) is like I said before 192.168.1.2, then the (internal) address is 192.168.80.1 on interface eth0:0 which is the same single nic....  then on the core, set your gateway as 192.168.1.1 which is your ddwrt router...

your devices will pull a dhcp address of 192.168.80.* with a listed gateway of 192.168.80.1...  however the core has a gateway of 192.168.1.1 (ddwrt router) so your devices on the 192.168.80.* subnet will still be able to get out on the internet because it is routed through your ddwrt...

rrambo

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Re: Single nic with dual dhcp
« Reply #2 on: December 04, 2007, 05:42:30 pm »
I missed the part where you said you wanted to have devices to be able to pull an address and access the internet when your core is down...  I have that problem when my core is occasionally down...  if I'm changing something on the core, etc...  I've given in to keeping the core up all the time except when I have to have it down for some reason..  if I have to absolutely have the core down for some reason I just set a static address on my laptop or whatever to the 192.168.1.* subnet and set the gateway as 192.168.1.1 for the ddwrt to access the internet until my core is back up...

totallymaxed

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Re: Single nic with dual dhcp
« Reply #3 on: December 05, 2007, 12:32:52 pm »
I missed the part where you said you wanted to have devices to be able to pull an address and access the internet when your core is down...  I have that problem when my core is occasionally down...  if I'm changing something on the core, etc...  I've given in to keeping the core up all the time except when I have to have it down for some reason..  if I have to absolutely have the core down for some reason I just set a static address on my laptop or whatever to the 192.168.1.* subnet and set the gateway as 192.168.1.1 for the ddwrt to access the internet until my core is back up...

I do exactly that too and I have the same router etc as you as well ;-)
Andy Herron,
Convergent Home Technologies Ltd
United Kingdom
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