This section describes the global settings that affect TCP, UDP, and ICMPv6 sessions, in addition to IPv6, NAT64, NAT oversubscription, jumbo frame size, MTU, accelerated aging, and captive portal authentication. There is also a setting (Rematch Sessions) that allows you to apply newly configured security policies to sessions that are already in progress.

The first few topics below provide brief summaries of the Transport Layer of the OSI model, TCP, UDP, and ICMP. For more information about the protocols, refer to their respective RFCs. The remaining topics describe the session timeouts and settings.