Is there any rule in networking which says that the ping(echo request) reply should come from the same path from which the ping(echo request) has been sent? For example If I ping 192.168.2.1 from R1's se0/0, according to my configuration the ping(echo request) should go from R1->R2->R3'(se0/1) and reply(echo request reply) should come from R3->R4->R1'(se0/0) since I have given static routes on all routers.
Configurations are as below:
R1#show ip int br | i up
Serial0/0 192.168.1.1 YES NVRAM up up
Serial0/1 192.168.4.1 YES NVRAM up up
R1#show running-config | sec ip route
ip route 192.168.2.2 255.255.255.255 192.168.1.2
R2#show ip int br | i up
Serial0/0 192.168.1.2 YES NVRAM up up
Serial0/1 192.168.2.2 YES NVRAM up up
R2#show running-config | sec ip route
ip route 192.168.3.1 255.255.255.255 192.168.2.1
R3#show running-config | sec ip route
ip route 192.168.4.2 255.255.255.255 192.168.3.2
R3#show ip int br | i up
Serial0/0 192.168.3.1 YES NVRAM up up
Serial0/1 192.168.2.1 YES NVRAM up up
R3#show running-config | sec ip route
ip route 192.168.4.2 255.255.255.255 192.168.3.2
R4#show ip int br | i up
Serial0/0 192.168.3.2 YES NVRAM up up
Serial0/1 192.168.4.2 YES NVRAM up up
R4#show running-config | sec ip route
ip route 192.168.1.1 255.255.255.255 192.168.4.1
Topology: