EIGRP Wide Metric Calculation

Using Throughput, Reliability, Load, and extended metrics EIGRP computes the composite metric using the following formula:


EIGRP Wide Metrics are supported where EIGRP named mode is possible.  The calculated value of the Wide Metrics can be much larger than the allowable 32 bit metrics the IPv4 RIB will accept.  As a result the composite metric has to be downscaled to be useable.

This is done by dividing the composite value by a factor configured in the metric rib-scale EIGRP command.  The default value is 128 and can be configured as necessary.

To clarify, EIGRP does not make its best path selection based on the downscaled value, instead it decides on the best path using the composite metric, and the successor path value is then downscaled and installed into the RIB.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s