In a high availability cluster in active-active mode, how is the SYN packet of an HTTP session offloaded to a slave unit processed?

In an active-active high availability cluster, both units (master and slave) share the load of traffic, allowing them to process requests simultaneously. When a SYN packet of an HTTP session is received, the initial processing occurs on the master FortiGate. In this architecture, the master unit is responsible for establishing the session and managing the session state, which includes the initial handshake, primarily represented by the SYN packet.

Once the master FortiGate receives the SYN packet from the internal host, it creates a session entry and then forwards the packet to the slave unit for further processing. This offloading mechanism is crucial for maintaining high performance and redundancy. The slave FortiGate can continue handling subsequent communication for that session, ensuring that traffic management is balanced.

The sequence of processing the SYN packet then flows as follows: the SYN request originates from the internal host, travels to the master FortiGate, which creates the session and communicates with the slave FortiGate. After this, the packet heads out to the Internet and subsequently to the web server. This entire process emphasizes the collaboration between the master and slave units to optimize resource usage while maintaining session continuity.

This is why the answer reflects this sequence clearly, showing how the master unit initially handles the SYN request