Tuning the EIGRP Metric Calculation
 


By default, EIGRP calculates an integer metric based on the composite metric of bandwidth and delay.  Both settings can be changed on any interface using the bandwidth value and the delay value interface subcommands.

Cisco recommends setting each interface’s bandwidth to an accurate value, rather than setting the bandwidth to change EIGRP’s metric calculation.  Although LAN interfaces default to accurate bandwidth settings, router serial links should be configured with the bandwidth speed command, with a speed value in kbps, matching the interface’s actual speed.

Because fewer features rely on the interface delay setting, Cisco recommends that if you want to tune EIGRP metric, change the interface delay settings.  To change an interface’s delay setting, use the delay value command, where the value is the delay setting with an unusual unit: tens-of-microseconds.  The EIGRP formula also uses the unit of tends-of-microseconds; however, show commands list the delay with a unit of microseconds