Exam 300-420 topic 1 question 188 discussion

https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/qos/vEdge-20-x/qos-book/forwarding-qos.html On Cisco vEdge devices and Cisco IOS XE SD-WAN devices, each interface has eight queues, which are numbered 0 to 7. Queue 0 is reserved, and is used for both control traffic and low-latency queuing (LLQ) traffic. For LLQ, any class that is mapped to queue 0 must also be configured to use LLQ. Queues 1 to 7 are available for data traffic, and the default scheduling for these seven queues is weighted round-robin (WRR). For these queues, you can define the weighting according to the needs of your network. When QoS is not configured for data traffic, queue 2 is the default queue. LLQ+WRR - but no such option.

The question is for the Queue schedule. On Cisco vEdge devices and Cisco IOS XE Catalyst SD-WAN devices, each interface has eight queues, which are numbered 0 to 7. Queue 0 is reserved, and is used for both control traffic and low-latency queuing (LLQ) traffic. For LLQ, any class that is mapped to queue 0 must also be configured to use LLQ. Queues 1 to 7 are available for data traffic, and the default scheduling for these seven queues is weighted round-robin (WRR). For these queues, you can define the weighting according to the needs of your network. When QoS is not configured for data traffic, queue 2 is the default queue. https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/qos/ios-xe-17/qos-book-xe/forwarding-qos.html

The queuing structure commonly used on SD-WAN Edge routers is "1P-4Q-2T" (1 Priority queue, 4 Queues, 2 Thresholds). In this queuing structure, different types of traffic can be classified and placed into separate queues based on their priority or class of service. It offers better control over traffic prioritization and quality of service. The priority queue is typically used for real-time traffic like voice, while the other queues are used for different levels of traffic prioritization.

Certainly not Priority. Priority Queuing = PQ is a set of four queues that is served in strict-priority order. The major drawback of this method is the starvation of lower-priority traffic. The only possible answer is LLQ+WFQ, however actual answer should be LLQ+WRR. Also SD-WAN has 8 queues unlike the 4 queues that is defined by Priority Queuing.

this seems to be the correct answer

On Cisco vEdge devices and Cisco IOS XE SD-WAN devices, each interface has eight queues, which are numbered 0 to 7. Queue 0 is reserved, and is used for both control traffic and low-latency queuing (LLQ) traffic. For LLQ, any class that is mapped to queue 0 must also be configured to use LLQ. Queues 1 to 7 are available for data traffic, and the default scheduling for these seven queues is weighted round-robin (WRR). For these queues, you can define the weighting according to the needs of your network. When QoS is not configured for data traffic, queue 2 is the default queue.

B. LLQ+WFQ https://www.networkacademy.io/ccie-enterprise/sdwan/qos#:~:text=When%20a%20WAN%20edge%20router,is%20used%20for%20control%20traffic.

WFQ uses weighted round robin scheduling and allows you to configure the weighting as a percentage of the bandwidth.. So LLQ+WFQ ? "B" looks ok to me.