Point-to-point (switch-to-switch) topology
In a point-to-point topology, each router needs a single security zone and single Tx-SC for encryption and a single Rx-SC for decryption. Each SC has two SAs. In total for a point-to-point topology, four SAs are needed: two Rx-SAs for Rx-SC1 and two Tx-SAs for Tx-SC1. The following figure shows the point-to-point topology.