How does BGP prefer the MED attribute during path selection?

The correct approach for BGP when selecting a path based on the MED (Multi-Exit Discriminator) attribute is to choose the path with the lowest MED value. The MED is used as a hint to indicate to external BGP (eBGP) neighbors the preferred path into a specific autonomous system (AS). A lower MED value signifies a more preferred route for traffic entering the AS. This enables better control over inbound traffic and helps guide it to the most efficient or desired path.

While other factors, such as local preference and AS path length, are evaluated in the decision-making process, when it specifically comes to the MED attribute, BGP operates under the principle that a lower MED is more favorable. This design allows network engineers to effectively influence routing decisions from neighboring autonomous systems based on their configuration of the MED values.

In summary, the choice of selecting the path with the lowest MED is fundamental to BGP's path selection criteria and is significant in managing how traffic enters an AS.