What does the Type 1 external route cost consist of?

The Type 1 external route cost represents the total cost associated with a route that is imported from an external Autonomous System (AS) into the routing table of another AS. This cost is a combination of two key components: the AS external cost and the AS internal cost.

The AS external cost reflects the metric defined by the originating AS for that external route, indicating how far or costly it is to reach that route from within the originating AS. On the other hand, the AS internal cost accounts for the cost of traveling through the intermediate AS to reach the external route.

When both of these costs are summed together, they provide a comprehensive view of the total distance (or cost) to reach the external destination. Understanding this relationship is crucial for effective routing decisions, as it ensures that the most efficient and economical paths are chosen for data transmission across different ASes.

Other options focus on only one of these costs or introduce unrelated factors, which do not encapsulate the full requirement for Type 1 external route calculation.