[Kea-users] Host reservations, bootfilename and client classes

Marcin Siodelski marcin at isc.org
Mon May 6 14:32:54 UTC 2019


Hello,

Your example JSON config didn't seem to make it through the email.

See my comments/questions inline.

On 30/04/2019 16:46, mkangelo wrote:
> Hi guys,
> 
> We are evaluating KEA (premium) as a potential replacement for our current
> DHCP infra, and we have few concerns over the following:
> 
> 1. Is it possible to have a custom bootFilename (option 67) set per host
> reservation while it references to a single client class? (this should not
> be part of the subnets).
> 

So, there is a subset of clients having host reservations, each client
having one of the classes assigned and each class coming with a
different option 67 value? Or it is that each client has its own option
67 value defined as the host reservation within the database?

> 2. Is it possible to prioritise bootFilename from a class (even if there is
> already a bootFilename set in the reservation) based on the matching client
> option (example 60, 77) ?
> 

It depends on the answer to the first question. Generally, options can
be freely ordered between classes. If the host reservation is made for a
class (not an option) and than for this class there is an option 67
value specified in the config file you can build the classes'
dependencies such that one or the other takes precedence. If you're
thinking to specify option 67 in the database (with host reservations),
then it becomes tricky because Kea has no knob to say that client class
specific option takes precedence over the option from the host reservation.

To expand on this, it would be useful to work on a specific example.

> To clarify:
> 
> - We need clients that have option 77 to receive bootFilename from a
> reservation and in case it doesn't have option 77 and matches just option 60
> to receive bootFilename from that class.
> 
> - There will be multiple classes configured, and we'd like the host
> reservations to be stored in a SQL database
> 

What do you mean by reservations? You mean values of the option 67 for
each host?

> 
> I'd appreciate some feedback.
> 
> 
> Example JSON config (classes and reservation - used for testing):
> 
> 
> 
> 
> 
> --
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> 

Marcin Siodelski
DHCP Software Engineer,
ISC


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