What is the role of a DiffServ-capable router?

A DiffServ-capable router is primarily responsible for classifying and managing network traffic based on priority. This functionality is crucial in environments where bandwidth is limited, and different types of traffic need to be treated differently to ensure optimal performance and user experience. By applying different levels of service to various data packets, the router can prioritize important traffic, such as voice or video, over less critical traffic, like file downloads or routine web browsing.

This classification process typically involves the router examining specific fields in the packet header to determine its priority level. Once identified, packets are marked accordingly, enabling the router and following network devices to provide the appropriate level of service throughout the transmission path. This approach significantly enhances the overall efficiency of data transmission, reduces latency for high-priority applications, and maximizes the use of available bandwidth.

Other options, while important for networking, do not pertain to the core functionality of DiffServ. Encrypting data packets, filtering unwanted traffic, and establishing network addresses serve different purposes within a network's operation and management.