Which technology allows QoS-marked traffic to be sent over a dedicated link?

Traffic policing meters and drops or re-marks traffic that exceeds a defined rate, but it does not influence which link the traffic is forwarded over.

MPLS provides label-switched paths and supports traffic engineering, but it does not inherently forward traffic over a specific link based on QoS markings applied at the IP layer without additional TE configuration.

PBR uses route-maps to match traffic attributes such as IP Precedence or DSCP markings and then set a specific next-hop or outgoing interface, effectively steering QoS-marked traffic over a dedicated link. This decouples forwarding decisions from the standard shortest-path routing table. No other listed technology provides this per-packet, policy-driven forwarding capability based on QoS marks.

Q-in-Q (IEEE 802.1ad) is a Layer 2 VLAN stacking mechanism used to tunnel customer VLANs across a provider network and has no function in steering QoS-marked traffic to a dedicated link.