Configuration by subclass and subnet

Glenn Satchell glenn.satchell at
Thu Oct 18 14:32:28 UTC 2012

The subnet (or pool) matches on each relay agent already, so putting it in
a class is making hard work for yourself.

If several subnets have the same option 43 value then they could be put in
a group.

A class for all the non-relay specific items is a good idea though, eg
base on vendor-id or other specific item that identifies those devices.

I think Simon also mentioned, that the dhcp server only sends the options
a client requests, so if the client doesn't request option 43 then it
won't be sent. This simplifies things a lot.


On Fri, October 19, 2012 1:18 am, Sten Carlsen wrote:
> On 18/10/12 13:42, Simon Hobson wrote:
>> Sten Carlsen wrote:
>>> I happened to think: could that option be put into the class
>>> definition? Or could the class definition be put into a group with
>>> the option statement?
>> I think that's what he already has - but he wants different options
>> depending on the subnet.
>> Another idea that comes to mind would involve two classes - and
>> explicitly put each AP in one or other class. Thta means more
>> maintenance as he would now need to keep track not only of the access
>> points, but also which subnet they are in (and hence which controller
>> they need configuring to use).
> Would selecting class based on relay address work?
> Each host would have membership in one class(C-1) based on the present
> criteria and another class(R-1) based on the relay address. Class R-1
> would then have the option 43 and class C-1 has other options.
> This is probably murky water, each host will then be member in two
> different classes - assuming that both class definitions contain
> options, how would dhcp resolve which options to use if the same option
> is set (differently) in both classes?
> I have never tried anything like this, never had the use. It might still
> be an interesting way to solve some challenges.
> --
> Best regards
> Sten Carlsen
> No improvements come from shouting:
>         "MALE BOVINE MANURE!!!"
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