Page 113 - Handout Computer Network.

Figure 5-6 shown a Routing Table

Routers keep track of important information in their routing tables: •
Protocol type
The type of routing protocol that created the routing table entry.

• Destination/next-hop associations

Tell a router that a particular destination is either directly connected to the router or that it
can be reached via another router called the next hop on the way to the final destination.
When a router receives an incoming packet, it checks the destination address and attempts
to match it with a routing table entry.

• Routing metrics

Different routing protocols use different routing metrics. Routing metrics are used to
determine a route’s desirability.
For example, RIP uses hop count as its routing metric. IGRP uses bandwidth, load, delay, and
reliability to create a composite metric value.

• Outbound interface

The interface that the data must be sent out to reach the final destination. Routers
communicate with one another to maintain their routing tables through the transmission of routing
update messages.

Depending on the particular routing protocol, routing update messages can be sent
periodically or only when there is a change in the network topology.