Summary

Routing is the process of moving information across an internetwork from source to destination. Routers are network devices using routing protocols to make decisions regarding how to forward traffic across an internetwork.

Routing involves two functions: determining the best routing path and transporting data traffic in the form of packets across the best path through an internetwork. Routing protocols use metrics to measure and determine which path is the best for a packet to travel through an internetwork. Metrics are standards of measurement, such as path bandwidth, used by routing algorithms to determine the best path to a destination network or host.

Routing algorithms are classified by type, as listed here:

• Static versus dynamic

• Single-path versus multipath

• Flat versus hierarchical

• Host-intelligent versus router-intelligent

• Intradomain versus interdomain

• Link-state versus distance vector

There is no right or wrong routing protocol to use when implementing a routed network. Certain routing protocols are more beneficial in certain network implementations; for example, RIP would serve a small network well, whereas a larger network might benefit from OSPF or EIGRP.

The network designer/administrator must take several factors into account when deciding which routing protocol to use, such as the protocol convergence rate in recovering from a disaster scenario like a network link failure.