option 82

Simon Hobson dhcp1 at thehobsons.co.uk
Tue Feb 5 07:54:05 UTC 2008

Peter Kringle wrote:

>Just trying bump this up, does anyone have any docs on how to set up 
>DHCPd to support Option 82?  I too need to do this.

You can't have looked very far in the archives then. It comes up 
regularly, and gets pretty well the same answers each time. I'm 
fairly sure there's has been an answered thread in the last month.

I summary :

1) Option 82 is supported as an option, though IIRC you have to define it.

2) You cannot use it as a key in a host statement.

3) There was a proposal for ISC to add a config option to override 
the default DB primary key selection (which is currently "match first 
value ( client_id, hardware)"). This was primarily for those that 
want to deal with the multiple addresses for multiboot systems issue 
but would probably have some application to Option82 users. This 
proposal has been on and off the work list and isn't currently 
scheduled for any specific release.

4) Again, there has been talk of having reserved leases, which 
together with the above would allow a lease to be reserved for a 
specific client. I don't think that has made it yet either.

5) I believe the 'normal' suggestion is to create a class for each 
switch port (ie matching on Option 82), and create a pool with only 
one lease (or as many as you wish to give to that port). It's a lot 
of config and "not elegant", but it should work.

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