[Kea-users] DHCP redundancy

[John Ratliff]

On 11/17/2017 9:37 AM, SoupNazi izaNpuoS wrote:
> Out of curiosity, was there a reason you didn't use the built in 
> failover configuration in ISC DHCP?

It's extremely confusing to me. Perhaps my understanding is flawed, but 
as I understand it, you need to split your pool and have one side 
responsible for their individual split. Our pools do not have enough 
spare IPs to allow that. It just never seemed work the effort.

--John

> 
> On Fri, Nov 17, 2017 at 9:25 AM, John Ratliff <john at bluemarble.net 
> <mailto:john at bluemarble.net>> wrote:
> 
>     I'm seeking best practice advice on how to setup DHCP server
>     redundancy with kea.
> 
>     With ISC DHCP, I used VRRP with two servers and configured it to
>     send the dhcp-server-identifier option as the VRRP IP. Then I would
>     run a script that sync'd the lease database automatically via cron.
> 
>     This process is messy and error prone, so I would like to use kea
>     instead.
> 
>     The subnets I am allocating via DHCP is not the same subnet that the
>     server is in, so we use ip-helper statements to forward DHCP
>     requests to the server.
> 
>     I have kea using mySQL as a lease backend. The mySQL server is not
>     on the same machine as kea.
> 
>     My first thought was to use VRRP and supply the
>     dhcp-server-identifier option again. I ran into a problem though
>     that if kea started before VRRP, it wouldn't listen on the VRRP IP.
>     There is probably a solution to that, but I don't have one yet.
> 
>     So then I changed the router configuration to use two ip-helper
>     statements, sending the request to both primary and secondary kea
>     servers; I also removed the dhcp-server-identifier option. This
>     seems to work.
> 
>     Is this a reasonable setup for DHCP redundancy with kea? Is there a
>     better option I might want to consider? Are there any concerns I
>     should be aware of with both servers being active?
> 
>     Thanks.
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