There are 4 types of packets for bundle operation: device track packet, user track packet, keepalive packet and start packet. Device track packet has information about device IP and it's status: is device Up or Down now. User track packet has information about currently active users and some information about it. Keepalive packet - about tacppd server activity with it's priority information. Start packet - notification about new member in bundle. Tacppd sends device track packet if it done icmp or snmp polling and detects device status change. The device track packet with information about down device can be sent only as result of polling operation. User track packet can be sent as result of snmp polling operation with user status Up or Down, and in case of receive tacacs+ accounting information, and can set user status in Up or Down. Keepalive packets - for selection of active server - this is server which do polling operation and do users drops by snmp - and provide information about server priority and do information about any server availability. Also server priority value have device track and user track packets and it replace keepalive packet if presents. Keepalive packets send every tacppd every 10 seconds. It has tacppd server ip and it's priority.