Option 82 & limit lease 1

Glenn Satchell glenn.satchell at uniq.com.au
Wed Apr 28 00:43:12 UTC 2010

The host-identifier is a data-expression, so you can use any of the 
operators in the dhcp-eval man page to combine them. For example

host-identifier concat( option agent.remote-id, option agent.circuit-id 
) "[some_static_RID_some_static_CID]";

You could also sue substring if there was a unique key or prefix within 
the remote_id.


On 04/28/10 05:54, Denis Laventure wrote:
> Hi Marc,
> Thanks for the tip on the host-identifier trick!
> It’s ok if you only need agent.circuit-id, but how do you manage
> agent.circuit-id from different agent.remote-id?
> Denis
> *De :* dhcp-users-bounces+denis_laventure=uqac.ca at lists.isc.org
> [mailto:dhcp-users-bounces+denis_laventure=uqac.ca at lists.isc.org] *De la
> part de* Marc Perea
> *Envoyé :* 22 avril 2010 17:38
> *À :* dhcp-users at isc.org
> *Objet :* Re: Option 82 & limit lease 1
>>From: Scott Baker <scott at perturb.org>
>>Subject: Re: Option 82 & limit lease 1
>>I think maybe I missed part of the conversation. What's "option matching"?
> Option matching appears to be a new feature in 4.2.x. It allows you to
> define a host by an option, instead of (in addition to?) by a
> mac-address. For a service provider, like us, this is a HUGE step
> forward (thanks btw to ISC for adding this feature). We've seen
> improvement of 2 orders of magnitude in performance over our old
> configuration on 3.1.2 both in restart times of the daemon and in
> DORA/second.
> As example, we used to define a class that matched on a specific option
> 82 (agent.circuit-id). Then we'd build a pool. Then we'd build a range
> (of 1 IP). Then apply the filter of our class to the range. For tens of
> thousands of customers, that's a very large conf file. And it's slow,
> _really_ slow.
> With 4.2, one can define a host and give it a fixed address. Done. It's
> very, _very_ nice. Smokin' performance too.
> And because I couldn't find it documented anywhere (man pages referred
> to ipv6, but this works in ipv4 too), it goes like:
> host [some_unique_host_name] { host-identifier option agent.circuit-id
> "[some_static_CID]"; fixed-address [a.b.c.d]; } #[some_customer_identifier]
> --Marc

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