Question

R1 has a primary EIGRP-learned route to 10.20.0.0/16 (internal EIGRP AD 90) via its WAN link. An engineer configures a static backup route, 'ip route 10.20.0.0 255.255.0.0 192.168.100.2', intending it to be used ONLY if EIGRP fails. After committing the change, users report that traffic to 10.20.0.0/16 is now flowing over the backup path even though the EIGRP neighbor is fully adjacent and the route is present in the EIGRP topology table. What is the cause and the correct fix?

Accepted Answer

The static route has a default AD of 1, which is lower than EIGRP internal (90), so it is installed in the RIB; configure the static route with a higher administrative distance (e.g., 'ip route 10.20.0.0 255.255.0.0 192.168.100.2 200').

Answer

The static route is more specific than the EIGRP route; change the static route mask to /24 so EIGRP remains preferred.

Answer

EIGRP internal routes have an AD of 170, which is higher than the static route; lower the EIGRP AD with 'distance eigrp 90 90'.

Answer

The static route must be redistributed into EIGRP before it can act as a backup; add 'redistribute static' under the EIGRP process.