Fix IP address based on the Option 82 info

Szabó, Gábor - COM FN szabo.gabor at
Tue Mar 21 16:10:10 UTC 2006

Dear list,
I'm looking for a solution assigning fix IP address based on the received Option 82 Circuit ID parameter.

Based on the documentation I have a working solution using classes according the configuration below:


class "DSLAM1_1_1_1_32" {match if option agent.circuit-id="DSLAM1 atm 01/01:1.32";}
class "DSLAM1_1_2_1_32" {match if option agent.circuit-id="DSLAM1 atm 01/02:1.32";}

subnet netmask
	option broadcast-address;
	option routers;
	pool { allow members of "DSLAM1_1_1_1_32"; range; }
	pool { allow members of "DSLAM1_1_2_1_32"; range; }

This is working, but I'm afraid that this is not really scalable for 50,000 - 100,000 users in a public environment.

Do somebody has a better/more simple idea? I have looked in DHCP documentation for any support of external scripts (DHCPD should call an external script with the option 82 CID and the script would return the IP address), but had not found. Also I have not found support for external database (SQL or LDAP) retrieving the IP address...

If I will have no other chance but to use the class-based approach do somebody a suggestion for fine-tuning the configuration file maximum performance? 
(For stress-test I have included about 100,000 "class" statement like the example above, it took for DHCPD few hours to start [on an Ultra 10] but after this it works...)

Any suggestion is welcome


Gabor Szabo

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