A variable or factor that a dynamic router can use to calculate its routing table to determine which path or route the router should use to forward a packet.
Routing metrics enable routers to make intelligent decisions about how to forward packets to ensure that
The simplest metric used by routers to calculate routing table entries is the number of hops to a given destination network. For example, this metric is used by the Routing Information Protocol (RIP), which allows dynamic routers to communicate with each other to share routing information and synchronize the entries of their routing tables. If you need more control over the paths that packets take, you can use protocols such as Open Shortest Path First (OSPF) Protocol and Interior Gateway Protocol (IGP), which can use a number of other metrics, including real-time metrics that routers determine dynamically, such as the following:
Other routing metrics are manually entered into the router configuration by network administrators who have a knowledge of the physical layout and performance of the network. Such metrics can include the following: