EIGRP - how metrics are sent in updates
EIGRP uses update messages to exchange route information between EIGRP routers. EIGRP uses various parameters to determine the metric to any particular destination. When an update is sent from one router to another, the actual metric value is not contained within the update, but the specific parameters that make up the metric are transmitted.
For example, in packet 5 of the following Cloudshark capture, you can see under the "Legacy Metric" heading the various components of the metric including delay, bandwidth, MTU, reliability, and load.
For calculations such as those involving the feasibility condition, these parameters are used to determine the metric and perform the appropriate calculations.
The actual EIGRP metric value is not contained within a field in the update.
Links:
https://forum.networklessons.com/t/eigrp-wide-metrics/2114/23?u=lagapidis
https://www.cloudshark.org/captures/bdcc74327b71
https://forum.networklessons.com/t/introduction-to-eigrp/881/192?u=lagapides