Bandwidth is a static metric assigned to each router interface using the ‘bandwidth’ command.
This metric simply measures the transmission speed of an interface. If no bandwidth command is configured on an interface IOS assigns an implicit bandwidth value to each interface, depending on its hardware type and operational characteristics.
When calculating the composite metric to a destination EIGRP takes the minimal bandwidth to a route into account. This is done by comparing the bandwidth as advertised by a neighboring router to the bandwidth of the interface toward the advertising neighbor and taking the lower value of the two.
Classic Metrics are capable of describing bandwidth in the range of 1kbps to 10Gbps.