|  | 1.4 | Routing Protocol
| 1.4.2 | Representing distance with metrics
When a routing algorithm updates the routing table, its primary objective is to determine the best information to include in the table. Each routing algorithm interprets "best" in its own way. The algorithm generates a number - called the metric value - for each path through the network. Typically, the smaller the metric number, the better the path. Metric values can be calculated based on a single characteristic of a path. You can calculate more complex metrics by combining several characteristics. The metrics most commonly used by routers follow: Bandwidth - Data capacity of a link. For instance, normally, a 10-Mbps Ethernet link is preferable to a 64-kbps leased line. Delay - Length of time required to move a packet from source to destination. Load - Amount of activity on a network resource such as a router or link. Reliability - Usually refers to the error rate of each network link. Hop count - Number of routers a packet must pass through. Ticks - Delay on a data link using IBM PC clock ticks (approximately 55 milliseconds). Cost - Arbitrary value, usually based on bandwidth, dollar expense, or other measurement, that is assigned by a network administrator.