To accelerate the rate of connection establishment, SecureXL groups all connection that match a particular...

 SecureXL templates are a mechanism to accelerate the rate of connection establishment by grouping connections that match a particular service and whose sole differentiating element is the source port. SecureXL templates enable even the very first packets of a TCP handshake to be accelerated, without waiting for the Firewall kernel to create a connection entry. The first packets of the first connection on the same service will be forwarded to the Firewall kernel, which will then create a template of the connection. The template will contain all the relevant information for the connection, such as source and destination IP addresses, destination port, NAT information, policy decision, etc. The template will be used by SecureXL to handle subsequent connections on the same service, without involving the Firewall kernel. This reduces the CPU load and increases the throughput.

There are three types of SecureXL templates: Accept, Drop, and NAT. Accept templates are used for connections that are allowed by the Firewall policy. Drop templates are used for connections that are blocked by the Firewall policy. NAT templates are used for connections that require NAT translation. Deny templates are not a valid type of SecureXL template.

References: SecureXL NAT Templates in R80.20 and lower, Part 3 - SecureXL, Security Gateway Performance Optimization - Part 5 - SecureXL