DHCP server behing Cisco relay

[José Queiroz]

Yes, that's it. The concept of dhcp relays is bound to the concept of
network segmentation. If your network is not segmented, you need shared
networks.

Be advised, however, that if you, later, need to offer DHCP also on the
192.168.200.0/24 network, you'll need a configuration much more elaborated.

2016-05-20 23:52 GMT-03:00 Hernan Saltiel <hsaltiel at gmail.com>:

> Thanks a lot!
> I'm using this configuration now, and is working perfectly.
> Best regards,
>
> HeCSa.
>
> On Fri, May 20, 2016 at 11:09 PM, Jeff Wieland <wieland at purdue.edu> wrote:
>
>> On May 20, 2016 4:58:23 PM EDT, Hernan Saltiel <hsaltiel at gmail.com>
>> wrote:
>>
>>> Hi everybody.
>>>
>>> Maybe I'm asking something previously answered.
>>> I configured my new iscp-dhcp-server (Ubuntu 16.04) to server requests
>>> from a network of APs.
>>> Those APs are connected to a Cisco switch, having 192.168.120.1/24 as
>>> primary address, and a secondary subnet with address 10.0.0.1/16 (yes,
>>> 16...). It has relay configured, just to send the dhcp requests to
>>> 192.168.120.20, a Windows machine.
>>> Today I have a Windows machine connected there, where I use the AP
>>> controller software, and TFTPD64, a thin software that works as a DHCP
>>> server. I configured there a range (10.0.0.10 -> 10.0.200.200) and
>>> everything works well, but it's Windows, then from time to time, I have to
>>> reboot the system.
>>> This is why I configured the new machine as 192.168.120.40/24,
>>> installed isc-dhcp-server package, and configured the following lines on
>>> /etc/dhcp/dhcpd.conf:
>>>
>>> default lease-time 600;
>>> max-lease-time 7200;
>>>
>>> subnet 10.0.0.0 netmask 255.255.0.0 {
>>>   range 10.0.0.10 10.0.200.200;
>>>   option subnet-mask 255.255.0.0;
>>>   option routers 10.0.0.1;
>>>   option domain-name-servers 8.8.8.8, 8.8.4.4;
>>> }
>>>
>>> subnet 192.168.120.0 netmask 255.255.255.0 {
>>> }
>>>
>>> When I start the server, I only see it trying to answer requests using
>>> network 192.168.120.0, then saying "no free leases", and not serving any
>>> 10.0.0.0/16 address.
>>>
>>> Now I'm living with TFTPD64, but I plan to move that to a better
>>> solution.
>>> Does anybody know about this configuration? Is there something I'm doing
>>> wrong?
>>> Thanks a lot in advance, and best regards.
>>>
>>> --
>>> HeCSa
>>>
>>> ------------------------------
>>>
>>> dhcp-users mailing list
>>> dhcp-users at lists.isc.org
>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>>
>>>
>> Since both networks are on the same wire, I believe that you need to
>> place your two subnet statements within a shared-network statement.
>> --
>> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>>
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>>
>
>
>
> --
> HeCSa
>
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