TCP out-of-state packet drop logging

Junos OS support logging of unsynchronized TCP out-of-state packets that are dropped by the flow module. Within any packet-switched network, when demand exceeds available capacity, the packets are queued up to hold the excess packets until the queue fills, and then the packets are dropped. When TCP operates across such a network, it takes any corrective actions to maintain error-free end-to-end communications. This feature enables packet recovery by logging the out-of-sync packets for error-free communication, and avoids database servers going out of sync. TCP packet drop logging occurs when: 

• TCP packets that trigger session creation are not synchronized. 
• TCP three-way handshake in flow fails. 
• TCP sequence check in flow fails. 
• TCP SYN packets are received in TCP FIN state. 

The unsynchronized TCP out-of-state packet drop log is a packet-based log, not a session-based log.