On Router 1, issue a ping command to the so-0/0/0 interface on Router 4 to send traffic across the IPSec tunnel.
user@R1> ping 10.1.56.2
PING 10.1.56.2 (10.1.56.2): 56 data bytes 64 bytes from 10.1.56.2: icmp_seq=0 ttl=254 time=1.351 ms 64 bytes from 10.1.56.2: icmp_seq=1 ttl=254 time=1.187 ms 64 bytes from 10.1.56.2: icmp_seq=2 ttl=254 time=1.172 ms 64 bytes from 10.1.56.2: icmp_seq=3 ttl=254 time=1.154 ms 64 bytes from 10.1.56.2: icmp_seq=4 ttl=254 time=1.156 ms ^C --- 10.1.56.2 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 1.154/1.204/1.351/0.074 ms