I found something relate to RedBack SMS http://publib.boulder.ibm.com/infocenter/wsphelp/index.jsp?topic=/com.ibm.wesm.doc/wesmadm-sms1800configuration.htm clips reauth-on-dhcp-lease-renew however, IP address is not a reauth attribute on SmartEdge.. Or maybe anyone knows if it's supposed to be in some predictive time ? Regards, Marcin