Question

An engineer redistributes OSPF into BGP on a border router using the command 'redistribute ospf 1' under the BGP address family. After the change, users complain that OSPF external routes (learned via redistribution from a remote EIGRP domain) are not reachable through the BGP core, although OSPF intra-area and inter-area destinations work fine. What is the most likely cause?

Accepted Answer

By default, 'redistribute ospf 1' into BGP only redistributes internal OSPF routes (intra-area and inter-area); external type-1 and type-2 routes require the 'match external' keyword

Answer

BGP cannot redistribute OSPF external routes because they have an administrative distance of 110, which BGP rejects during redistribution

Answer

The OSPF external routes are filtered because BGP synchronization is enabled and no matching IGP route exists

Answer

A seed metric must be configured with 'default-metric' or the OSPF external routes are assigned a metric of infinity and discarded