Cisco SD-WAN edge routers use a queuing model based on LLQ and WFQ concepts. Low Latency Queuing provides strict priority treatment for delay-sensitive traffic such as voice and real-time media, while Weighted Fair Queuing gives proportional service to other traffic classes based on bandwidth allocation. This combination aligns with SD-WAN requirements where business-critical and real-time traffic must be protected without starving normal data applications. FIFO is not appropriate for a multi-class WAN design because it does not distinguish application priority during congestion. A pure priority queue would risk starving lower-priority traffic if it were not controlled by policing or bandwidth limits. Hardware-specific campus queuing models such as 1P-4Q-2T describe certain switch egress queue structures, not the generic SD- WAN edge queuing architecture. In a professional SD-WAN QoS design, traffic is classified, marked, mapped to forwarding classes, and then scheduled using priority and weighted queues according to business intent. Reference topics: Cisco SD-WAN QoS, LLQ, WFQ, forwarding classes, application-aware WAN policy.