[ale] dhcpd to multiple vlans from one server

[Michael Trausch]

If you will have variable requirements, make the DHCP server managed by a tool to generate its configuration. DRY is just as important in business processes as it is in software design and development.

A little GTK tool which generates the net-up script and the DHCP server config using a template would take perhaps a work-day, and be well worth the investment.

Sent from my iPad

> On Jan 22, 2015, at 9:41 PM, "Robert L. Harris" <robert.l.harris at gmail.com> wrote:
> 
> 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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