In such context, a bottleneck link for a given data flow is a link that is fully utilized (is saturated) and of all the flows sharing this link, the given data flow achieves maximum data rate network-wide.
[1] Note that this definition is substantially different from a common meaning of a bottleneck.
Also note, that this definition does not forbid a single link to be a bottleneck for multiple flows.
Identifying and managing bottlenecks is crucial for maintaining optimal performance in networked systems.
Strategies to mitigate the impact of bottleneck links include increasing the capacity of the bottleneck link, optimizing traffic management, and using load-balancing techniques to distribute data flows across multiple paths.