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Dynamic routing offers more flexibility. According to the routing table generated by
Router A, a packet can reach its destination over the preferred route through Router D.
However, a second path to the destination is available by way of Router B.

When Router A recognizes that the link to Router D is down, it adjusts its routing table,
making the path through Router B the preferred path to the destination. The routers continue
sending packets over this link. When the path between Routers A and D is restored to service,
Router A again can change its routing table to indicate a preference for the counterclockwise
path through Routers D and C to the destination network.

Dynamic routing protocols also can direct traffic from the same session over different
paths in a network for better performance. This is known as load sharing.
6.5.6 Dynamic Routing Operations

The success of dynamic routing depends on two basic router functions:

• Maintenance of a routing table

• Timely distribution of knowledge, in the form of routing updates, to other
routers, see Figure 6-11 shown a Maintenance of Routing Information in Routing
Protocols

Figure 6-11 shown a Maintenance of Routing Information in Routing Protocols

Dynamic routing relies on a routing protocol to share knowledge among routers.

A routing protocol defines the set of rules used by a router when it communicates with
neighboring routers.
For example, a routing protocol describes the following:

A. How to send updates

B. What knowledge is contained in these updates

C. When to send this knowledge

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