All traffic from the clients alice and venus is tunneled by default gateway moon to VPN gateway sun. In order to prevent local traffic within the 10.1.0.0/16 subnet to enter the tunnel, a local-net shunt policy with type=pass is set up. In order for the shunt to work, automatic route insertion must be disabled by adding install_routes = no to the charon section of strongswan.conf.
In order to demonstrate the use of type=drop shunt policies, the venus-icmp connection prevents ICMP traffic to and from venus to use the IPsec tunnel by dropping such packets. Thanks to the local-net pass shunt, venus and moon can still ping each other, though.