A connection between the subnets behind the gateways moon and sun is set up. With esp=aes128-sha256-esn-noesn! gateway moon proposes the use of Extended Sequence Numbers but can also live without them. Gateway sun defines esp=aes128-sha256-esn! and thus decides on the use of ESN.

Upon the successful establishment of the CHILD SA with ESN, client alice behind gateway moon pings client bob located behind gateway sun 10 times.