rlm_ippool.so missing ?

Hello all, When I was trying to run Freeradius, I got the following errors. It says no "rlm_ippool.so" exists. I took a look into /usr/local/lib, and there is no such file. Could someone help me on this? Thanks so much. I need to let Freeradius assign dynamic IP address from IP_Pool to PPPoE clients. Here is the error message: /usr/local/etc/raddb/radiusd.conf[1739]: Failed to link to module 'rlm_ippool': rlm_ippool.so: cannot open shared object file: No such file or directory /usr/local/etc/raddb/sites-enabled/default[354]: Failed to find module "main_pool". /usr/local/etc/raddb/sites-enabled/default[352]: Errors parsing post-auth section.