[Kea-users] kea 2.0.3 dhcp4 HA not working

[vom513]

> On Apr 20, 2023, at 2:50 PM, Peter Davies <peterd at isc.org> wrote:
> 
> Hi -
>    Thanks for the log files.
> 
> There isn't much to comment on here. Your HA configuration appears to be working.
> HA Heartbeat commands are being sent and received correctly in both directions.
> There are some HA warnings but they were generated on kea-1 before kea-2 was up
> and running, and on kea-2 after kea-1 had been shut down.
> 
> What I don't see is any dhcp traffic.
> 
> I suggest you let the servers run for a while and see what happens. If you can't
> use live DHCP traffic you can use "perfdhcp" or "dhclient" to generate some.
> 
> For the secondary to start processing DHCPDISCOVERs the  HA parameters
> "max-unacked-clients" and "max-ack-delay" are considered as well as the status of the primary.
> The default value for the "max-ack-delay" parameter is 10000 milliseconds.
> The default value of the  "max-unacked-clients"  parameter is 10.
> see: https://kea.readthedocs.io/en/kea-2.0.3/arm/hooks.html#load-balancing-configuration
> 

I think this made me realize the behavior here.  Since this is a lab - it’s very “quiet”.  I only have a few machines that I ifup/down/reboot/etc to get DHCP requests going.  I have now set unacked clients to 0 and I get my expected behavior (i.e. immediate (well after the timers…) transition to an active state).  

> When you have your configuration working,  I  suggest you also consider enabling multi-threading.
> see: https://kea.readthedocs.io/en/kea-2.2.0/arm/dhcp4-srv.html#multi-threading-settings
> 
> With multi-threading enabled, you can enable multi-threaded HA.
> see: https://kea.readthedocs.io/en/kea-2.2.0/arm/hooks.html#multi-threaded-configuration-ha-mt
> 
> Multi-threaded HA creates a direct HA connection between the HA servers and does
> not go through the control agent.

I will definitely read through the docs on this.  And I know this next question may be a bit difficult/subjective perhaps to answer - but my use case is my home network with fairly long leases.  It’s also on the “quiet” side.  This obviously isn’t the load/rps of say a college campus, municipal wifi, etc.  Would multithreading still be recommended ?  I’ve been running ISC dhcpd for years with no issues.

Thanks again.