Restricting ONT's Ethernet port to singe active IP address

Jerimiah Cole jcole at
Wed Apr 22 20:07:04 UTC 2009

Frank Bulk wrote:
> Option 82 support seems like the closest way to get it done, by creating 
> classes and handing out an static IP, but I understand the process 
> correctly, it requires generating a class for each Option 82 string and 
> assigning a static IP address.  That has the negatives of creating 
> classes in advance and giving out statics when I don’t want to give out 
> statics.

Enter ISC's "spawning class" concept:

class "tbtc-dsl-occam" {
   match if substring(option agent.remote-id,0,5) = "Occam";
   spawn with concat(option agent.remote-id, " ", option agent.circuit-id);
   lease limit 2;

The "spawn with x" option dynamically creates a class for each unique 
"x", in my case the concatenation of the remote-id and circuit-id.

The lease limit is 2 to permit people to swap out devices without having 
to release.

I'd also recommend "mac limit 2" in your access profiles.


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