300-415 Question #289: Real Exam Question with Answer & Explanation

Question

Options

• AHub sdwan interface GigabitEthernet1 qos-adaptive period 90 downstream 8000 downstream range 6000 10000 upstream 8000 upstream range 4000 16000 exit tunnel-interface encapsulation ipsec weight 1 color public-internet no last-resort-circuit vmanage-connection-preference 5 allow-service all
• BHub sdwan interface GigabitEthernet1 qos-adaptive period 90 downstream 10000 downstream range 8000 12000 upstream 9000 upstream range 5000 16000 exit tunnel-interface encapsulation ipsec weight 1 color mpls no last-resort-circuit vmanage-connection-preference 5 allow-service all
• CSite A (Spoke) sdwan interface GigabitEthernet1 qos-adaptive period 90 downstream 8000 downstream range 6000 10000 upstream 8000 upstream range 4000 16000 exit tunnel-interface encapsulation ipsec weight 1 color public-internet no last-resort-circuit vmanage-connection-preference 5 allow-service all
• DSite A (Spoke) sdwan interface GigabitEthernet1 qos-adaptive period 90 downstream 10000 downstream range 8000 12000 upstream 9000 upstream range 5000 16000 exit tunnel-interface encapsulation ipsec weight 1 color public-internet no last-resort-circuit vmanage-connection-preference 5 allow-service all

Explanation

The correct configuration enables adaptive QoS on the Spoke router's public-internet tunnel interface, allowing traffic shaping to dynamically adjust its bandwidth based on real-time network conditions within specified upstream and downstream ranges.

Common mistakes.

• A. This configuration is applied to the Hub router, but the requirement specifies configuring a QoS policy 'between the hub and site A (spoke)' where the adaptive shaping is typically applied on the spoke's internet circuit.
• B. This configuration is applied to the Hub router and uses the mpls color, which does not match the requirement for a 'standard Internet circuit' for Site A (spoke).
• C. While applied to Site A (Spoke) and using public-internet color, the specific downstream and upstream bandwidth values and ranges differ from the intended correct answer. Without an exhibit, the precise numerical values are arbitrary, but D is the designated correct option for this scenario.

Concept tested. Cisco SD-WAN adaptive QoS on spokes

Reference. https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/qos-book/sdwan-qos-book_chapter_010.html

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