Question

You are troubleshooting an EIGRP named-mode deployment. R1 runs a legacy classic-mode EIGRP configuration for autonomous system 100, while its neighbor R2 has recently been migrated to EIGRP named mode using the same AS. The two routers form an adjacency and exchange routes, but you notice that the metrics for the same destinations differ significantly between the two routers, and traffic engineering based on delay is not behaving as expected. The link between them is a 10 Gbps interface. Which explanation best accounts for the metric discrepancy?

Accepted Answer

Named mode uses 64-bit wide metrics by default, so R2 scales the composite metric differently than R1's classic 32-bit metric for high-bandwidth interfaces

Answer

The adjacency should not have formed at all because classic and named mode routers cannot become neighbors within the same AS

Answer

R2 in named mode automatically disables auto-summary while R1 leaves it enabled, causing the metrics to be recalculated

Answer

Named mode changes the default K-values to K1=1, K2=1, K3=1, K4=1, K5=1, which changes the composite metric calculation