Company ABC grew organically and now their single-area OSPF network has an unacceptably slow convergence time after a topology change. To address the slow convergence time, they want to introduce a mu

When an ABR advertises a summary prefix, routers outside that area lose visibility into the specific destinations behind it and cannot determine the optimal exit point, so traffic may be directed toward an ABR that is not the closest to the actual destination. In designs with multiple ABRs advertising the same or overlapping summaries, this loss of specific reachability information makes suboptimal routing the primary and unavoidable trade-off of summarization.

Multiarea OSPF reduces SPF computation overhead by constraining LSA flooding and the topology database to each individual area, so SPF calculations become faster, not slower.

Increased operational complexity is a real secondary drawback of multiarea OSPF, but it is not the main technical concern specifically caused by address summarization.

Summarization reduces the number of prefixes advertised between areas, which decreases routing table size and lowers memory consumption across non-ABR routers rather than increasing it.