Question

A service provider is designing the QoS architecture for its MPLS backbone. At the ingress PE, customer traffic arrives with untrusted DSCP markings that the SP does not wish to honor. The design team wants to enforce the SP's own traffic classes at the network edge while ensuring core routers can make forwarding decisions quickly without re-inspecting deep packet fields. Which QoS architecture approach best meets these requirements?

Accepted Answer

Perform complex classification and re-marking at the ingress PE (trust boundary), then have core (P) routers act on the simplified marking using per-hop behaviors

Answer

Trust the customer DSCP values end-to-end and configure identical deep classification ACLs on every P router in the core

Answer

Disable classification at the PE and rely solely on interface-level shaping on each core link to differentiate traffic

Answer

Perform re-marking only at the egress PE so the core continues to forward based on the original customer markings