Circuit tunnels are used to route traffic between two clusters. The traffic is tapped and sent through network ports on the TAP landing nodes in a cluster. Based on the flow map configuration, traffic is filtered at the TAP landing nodes and sent to the circuit ports. The circuit ports encapsulate the traffic with a Circuit ID and routes the encapsulated traffic through a circuit tunnel. At the receiving end, the traffic is decapsulated and sent to the tool ports. The circuit tunnels are bidirectional. For more information about circuit tunnels, refer to About Circuit-ID Tunnels.