Let's say computer S (sender) sends some IP packets to computer R (receiver). Between S and R, there are 6 networks, divided by 5 routers. So the IP packets leave R, go through network 1, pass router ...
In IPv4, fragmentation is done by routers on way to the destination if DF(do not fragment) flag is not set in the IP packet. Once a packet is fragmented, its fragments may take different paths (due ...