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The routing protocol also determines whether just the changed routes or the entire routing
table is sent in the routing update.
By analyzing the routing updates from the neighboring routers, a router can build and
maintain its routing table.
https://www.youtube.com/watch?v=gQtgtKtvRdo&t=77s
5.4 Routing Algorithms and Metrics
Routing protocols often have one or more of the following design goals:
• Optimization
Optimization describes the capability of the routing protocol/ algorithm to select the best
route, depending on metrics and metric weightings used in the calculation.
For example, one algorithm might use hop count and delay for its metric but might weigh
delay more heavily in the calculation.
• Simplicity and low overhead
Ideally efficient routing algorithm functionality is achieved if the routers have minimum CPU
and memory overhead.
This is important so that the network can scale to large proportions, such as the Internet.
• Robustness and stability
A routing algorithm should perform correctly in the face of unusual or
unforeseen circumstances, such as hardware failures, high load conditions, and
implementation errors.
• Rapid convergence
Convergence is the process of all routers agreeing on routes. When a network event causes
changes in router availability, recalculations are needed to reestablish network connectivity. Routing
algorithms that converge slowly can cause data to not be delivered.
• Flexibility
A routing algorithm should quickly adapt to a variety of network changes. These
changes include router availability, changes in bandwidth, queue size, and network delay.
• Scalability
Some routing protocols are better designed for scalability than others. It is important to keep
in mind that if the network is intended to grow (or even if this option is to be left open), a routing
protocol such as EIGRP rather than RIP should be used. When a routing algorithm updates a routing
table, its primary objective is to determine the best information to include in the table.
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