Describe basic
routing concepts
·
Introduction to IP Routing
IP routing—the process
of forwarding IP packets—delivers packets across entire TCP/IP networks, from
the device that originally builds the IP packet to the device that is supposed
to receive the packet. In other words, IP routing delivers IP packets from the
sending host to the destination host.
Routers don’t really
care about hosts they care only about networks and the best path to each
network. The logical network address of the destination host is used to get
packets to a network through a routed network, and then the hardware address of
the host is used to deliver the packet from a router to the correct destination
host.
Routing table is used
to find best path to destination. Forwarding decisions based on Layer 3. IP
performs search for a matching host address, search for a matching network
address, and search for a default entry, Routing done by IP router, when it
searches the routing table and decides which interface to end a packet out.
When a router receives
a packet, it examines the destination IP address. If the destination IP address
does not belong to any of the router’s directly connected networks, the router
must forward this packet to another router.
Fig shows Basic IPRouting.
There are two types of
Routing:
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