[ale] dhcpd to multiple vlans from one server

[Robert L. Harris]

I have multiple projects/products, etc at work we are breaking into
separate broadcast domains ( currently 11, likely to be closer to 20 ).  I
don't want a different dhcp server per subnet/vlan.  I can put a trunk port
to the dhcp server so if I can have dhcpd answering on each vlan so I have
centrally managed dhcp, that's ideal.  So maybe I'm stuck doing the
eth0.21, etc with an IP on each subnet and one dhcp server.



On Thu Jan 22 2015 at 7:30:43 PM Jim Kinney <jkinney at jimkinney.us> wrote:

> +1. All it takes is a physical connection to the subnet.
>
> Not sure why separate vlans get assigned to separate subnets. It doesn't
> provide a benefit. Vlans are for having overlapping IP space in the same
> physical LAN. Which is only useful when a LAN fills up a 10. Class A. Maybe
> its easier at the switch/router management level with more than 100
> subnets. Mostly, I see it used as a job guarantee for a network admin.
>
> On January 22, 2015 9:15:39 PM EST, Michael Trausch <mike at trausch.us>
> wrote:
>
>> ISC dhcpd will hand an address out based on the interface it came in on.
>> If if eth0 has 203.0.113.1/25 and eth1 has 203.0.113.129/25, and the
>> DHCP server is authoritative for those two subnetworks, then when it
>> receives a request on eth0 for an address it will issue an address in
>> 203.0.113.0/25; when it receives a request on eth1 it will issue an
>> address in 203.0.113.128/25.
>>
>> Sent from my iPad
>>
>> On Jan 22, 2015, at 7:37 PM, "Robert L. Harris" <
>> robert.l.harris at gmail.com> wrote:
>>
>> Ok, so if I have 2 subnets:
>>
>> 172.20.1/24 on vlan 21
>> 172.20.2/24 on vlan 22
>>
>> If a host plugs into a port assigned to vlan 22, how do I make sure dhcpd
>> gives out the right address?  That's the part of the designation I'm
>> missing.
>>
>> Robert
>>
>>
>> On Thu Ja n 22 2015 at 5:17:25 PM James Sumners <james.sumners at gmail.com>
>> wrote:
>>
>>> You just have to define the subnets in the config and put each subnet's
>>> pool within its respective block. No need for aliased IPs.
>>>
>>> On Thursday, January 22, 2015, Robert L. Harris <
>>> robert.l.harris at gmail.com> wrote:
>>>
>>>>
>>>> Anyone have a dhcpd serving multiple subnets to multiple vlans from a
>>>> single server on a trunk they can share configs?  I don't want to spawn a
>>>> bunch of servers and if I can do it with a single interface that would be
>>>> ideal.  If I have to go with eth0.0, eth0.1, etc that's a good second
>>>> choice.
>>>>
>>>> Robert
>>>>
>>>>
>>>
>>> --
>>> James Sumners
>>> http://james.sumners.info/ (technical profile)
>>> http://jrfom.com/ (personal site)
>>> http://haplo.bandcamp.com/ (band page)
>>>
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> --
> Jim Kinney
> Linux Systems Analyst
> Physicist/Brewer
> http://jimkinney.us
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