In an MPLS L3VPN hub-and-spoke IP/VPN design, what must be configured to bypass BGP AS_PATH loop prevention?

In an MPLS L3VPN hub-and-spoke design, the spoke sites often belong to the same autonomous system (AS) as the hub. When the hub PE router advertises routes learned from one spoke to another spoke, BGP's ASPATH loop prevention mechanism will discard the route if the receiving spoke's AS is already present in the ASPATH. To bypass this, the as-override command is used at the PEHub. This command replaces the spoke's AS number in the ASPATH with the hub's AS number when advertising routes between spokes, effectively tricking BGP into accepting the route. allowas-in is used when a PE needs to accept routes that already contain its own AS in the ASPATH, typically for specific scenarios like back-door links, but it's not the primary solution for the hub-and-spoke ASPATH issue. Applying as-override at all PEs or using allowas-in in conjunction with as-override at the PEHub are not the most precise or efficient solutions for this specific problem.