Using Option 82 for static ip assignment

Eric Helm helmwork at
Wed Aug 23 17:42:26 UTC 2006

We have a FTTP deployment where the fiber switch adds the
agent.circuit-id information to the DHCP packets. I am using this
information to assign a static IP for each subscriber.
When the subscriber equipment is changed, I see a log message that says
'no free leases' and the device does not get an IP assigned. Once the
lease for the old equipment expires, everything is good to go.

In this scenario, is my only course of action to reduce the lease times?

Here is part of my config:

lease-file-name "/etc/dhcp/dhcpd.leases";
pid-file-name "/var/run/dhcp/";
log-facility local1;
option domain-name "";
option domain-name-servers,;
option classless-routes code 121 = array of unsigned integer 8;
default-lease-time 1800;
max-lease-time 43200;
option time-offset -21600;
option ip-forwarding off;
ping-check on;

class "Occam_Lab_ONT"
        match if option agent.circuit-id = "occam-9/Ethernet1:vlan2";

subnet netmask #Occam FTTH Lab
                allow members of "Occam_Lab_ONT";
                failover peer "failover";
                deny dynamic bootp clients;
        option routers;
        option broadcast-address;
        option tftp-server-name "";
        filename "OccamONT2342.cfg";


More information about the dhcp-users mailing list