12-30-2020 04:06 AM
Hey everyone,
I recently encountered a unique situation and am unsure on how to approach it. I have a DHCP configure on my default gateway and a client have recently come with a strange request. He needs my DHCP to not give a default gateway alongside his IP address and he needs it for a few other PC's in this subnet. Now I know a solution would be to configure a manual IP address but the some of the user equipment in the subnet cannot support manual IP configuration and they need to get it from a DHCP but we don't want them to receive a default gateway. I tried creating a different DHCP pool for the specific clients but for some reason the pool inherited and assigned a default gateway even though in the pool itself or was no configured, he inherited the default gateway from the bigger pool (I'm guessing because the pools are in the same subnet). So is there a solution to this? Thanks!
12-30-2020 04:12 AM - edited 12-30-2020 04:12 AM
never tried it but i read the document some time same requirement - try and let us know outcome.
dhcp-option=3 to disable setting the default gateway
RFC for reference :
https://www.iana.org/assignments/bootp-dhcp-parameters/bootp-dhcp-parameters.xhtml
12-30-2020 05:35 AM
Hello,
what are you using as DHCP server ?
You could just set a dummy default gateway, such as 169.254.1.1, I know that on Cisco IOS DHCP pools, that address will be assigned to clients, it does not need to match the actual network of the pool...
12-30-2020 08:09 AM
I do not see how 2 pools using the same IP subnet is going to work. I believe that a solution for the original poster would be to configure the normal DHCP pool (including the default gateway) to be used for most of the devices and to configure manual reservations specifying the mac address of devices which should not receive default gateway and in the manual reservation simply do not specify a default gateway.
12-31-2020 03:50 AM
I did exactly that but as I sais the reservation "inherits" the "default router" option. I'm guessing since the reservation and the rest of the pool are on the same subnet. I tried creating an entirely different pool with the "host" configuration but even a different pool inherits a default router option. And assigning a meaningless gateway is not going to work since the whole reason these few users don't want the equipment to receive a default gateway in this subnet is because the equipment has two networks on it and already has one default gateway from the other network, and they don't want the equipment to have two gateways since that messes with the equipment's traffic, it obviously doesn't know where to send packets with two gateways. The DHCP server is the Cisco router which also functions as the network's default gateway so it's not an actual server.
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