13.25 NAT with Overlapping Subnets=Routing issue in SG
I may miss something but I don´t understand how INE can get the solution to work when pinging from R2 loopback 1 to R1 (220.127.116.11):
Rack1R2#ping 18.104.22.168 source loopback 1 repeat 2
Type escape sequence to abort.
Sending 2, 100-byte ICMP Echos to 22.214.171.124, timeout is 2 seconds:
Packet sent with a source address of 10.0.0.2
Success rate is 100 percent (2/2), round-trip min/avg/max = 60/62/64 ms
The debug nat on R1 says clearly the following after NAT translation have occured when traffic is sended back from R1 to R2:
NAT: i: icmp (10.0.0.1, 20) -> (126.96.36.199, 20) 
NAT: s=10.0.0.1->188.8.131.52, d=184.108.40.206 
NAT: s=220.127.116.11, d=18.104.22.168->10.0.0.2 
So after NAT translation of both source and destination IP the router makes a post-nat routing lookup and ends up with an encapsultion failed as the destination IP is directly connected to R1 (loopback 1):
IP: s=22.214.171.124 (local), d=10.0.0.2 (Serial0/0/0), len 100, encapsulation failed
But I may miss something there.