Metrics (networking)
# Metrics (networking)

Router metrics are configuration values used by a router to make routing decisions. A metric is typically one of many fields in a routing table. Router metrics help the router choose the best route among multiple feasible routes to a destination. The route will go in the direction of the gateway with the lowest metric.

A router metric is typically based on information such as path length, bandwidth, load, hop count, path cost, delay, maximum transmission unit (MTU), reliability and communications cost.

## Examples

A metric can include:

* measuring link utilization (using SNMP)
* number of hops (hop count)
* speed of the path
* packet loss (router congestion/conditions)
* Network delay
* path reliability
* path bandwidth
* throughput [SNMP - query routers]
* load
* Maximum transmission unit (MTU)
* administrator configured value

In EIGRP, metrics is represented by an integer from 0 to 4,294,967,295 (The size of a 32-bit integer). In Microsoft Windows XP routing it ranges from 1 to 9999.

A metric can be considered as:

* additive - the total cost of a path is the sum of the costs of individual links along the path,
* concave - the total cost of a path is the minimum of the costs of individual links along the path,
* multiplicative - the total cost of a path is the product of the costs of individual links along the path.

## Service level metrics

Router metrics are metrics used by a router to make routing decisions. It is typically one of many fields in a routing table.

Router metrics can contain any number of values that help the router determine the best route among multiple routes to a destination. A router metric typically based on information like path length, bandwidth, load, hop count, path cost, delay, MTU, reliability and communications cost.

