Configuration by subclass and subnet

Sten Carlsen stenc at
Thu Oct 18 14:41:07 UTC 2012

On 18/10/12 16:32, Glenn Satchell wrote:
> 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.
Right, my question was also more generic, IF for some obscure reason I 
decide it makes sense to have two classifications based on X and Y , so 
I would have, say:

classes X1, X2, X3, ...
classes Y1, Y2, Y3, ...

All devices belong to one of the Xn classes *and* to one of the Yn 
classes. This could give me some freedom to use allow/deny to allocate 
from pools, etc.

I happen to put option Z in both class X3 and Y2 (my mistake or 
something very convoluted) how would dhcp decide which option Z to use? 
the one from X3 or the one from Y2?
> regards,
> -glenn
> 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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Best regards

Sten Carlsen

No improvements come from shouting:


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