(Note: Corrected the typo in the original prompt where " Online " was used instead of " Only " .)
Redistribution between an Exterior Gateway Protocol (BGP) and an Interior Gateway Protocol (OSPF) is a high-risk operation on AOS-CX switches that requires careful planning.
Scale and Performance: BGP is designed to carry thousands (or even millions) of routes. OSPF is a link-state protocol that requires every router in an area to maintain an identical Link State Database (LSDB). If you were to redistribute a full BGP table into OSPF, the resulting flood of Type 5 LSAs would likely crash the OSPF process, consume all available switch memory, and cause network-wide instability.
The " Only Defined Routes " Rule: Aruba best practices dictate that you should use Route Maps to strictly control (define) which specific BGP prefixes are allowed into the OSPF domain. This ensures only necessary destination networks (like a remote branch office) are advertised to the campus routers, protecting the OSPF area ' s resources.
Evaluating Other Options:
Option A: While redistributing only a default route is a very safe strategy, it isn ' t a " universal truth " because some designs require specific internal subnets to be shared.
Options B and C: Choosing between External Type 1 (E1) and External Type 2 (E2) is a design choice regarding how costs are calculated (E1 adds internal path cost, E2 stays constant). Neither is an " always " requirement; the primary concern is the volume and definition of the routes being moved.
