When a packet arrives at the firewall, it always hits the SecureXL Implementation Module (sim) kernel driver running on an SND/IRQ core first. In R80.20+ if the packet's attributes match a connection in the SecureXL state table (fwaccel conns - in other words SecureXL is handling that connection), SecureXL commences direct processing on that packet. If the packet does not match a connection in the SecureXL state table because it is the first packet of a new connection, or it is part of an existing unaccelerated connection that is not being handled by SecureXL, the packet is sent up to a Firewall Worker/Instance which is maintaining its own state table (fw tab -t connections). There is a notification mechanism to sync certain operations between the two separate tables.
Gateway Performance Optimization R81.20 Course
now available at maxpowerfirewalls.com