IP routing

A datagram is generated by either a localhost or any other host. When this datagram seems to generate from any host other than localhost, then the host may work as a router. These hosts contain routing tables which help route datagrams. When any datagram is received by a host and not belong to it, gets dropped (silently discarded). This routing of datagram done by host as router is IP routing. Lets see how routing is done.
IP routing:
A datagram is either generated or forwarded by a system. A search for routing table is done for this generated datagram. This table is updated by either a routing daemon or ICMP redirects. Static routes can be entered by using the route command. ICMP redirects updates routing table dynamically.