Multiple Inline Pairs and Asynchronous Routing

You can configure the interfaces to route traffic between a host on your network and external hosts through different inline pairs, depending on whether the traffic is inbound or outbound. This is an asynchronous routing configuration. If you deploy asynchronous routing, but you include only one inline pair in an inline set, the device might not correctly analyze your network traffic because it might see only half of the traffic.

Adding multiple inline pairs to the same inline set lets the system identify the inbound and outbound traffic as part of the same traffic flow. For passive interfaces only, you can also achieve this by including the interface pairs in the same security zone.

Note	If you assign multiple inline pairs to a single inline set, but you experience issues with duplicate traffic, you might need to reassign your inline pairs to separate inline sets or modify your security zones.