An engineer is configuring QoS for a 100 Mb WAN link.
An ISP SLA was signed to support 70% of the link.
Which QoS command allows the engineer to use 70% of the link while maintaining a steady flow?
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A. B. C. D.D.
The correct answer for this question is option D: "traffic-shape rate 70000000 8750000 8750000".
Explanation:
QoS is used to prioritize traffic on a network, ensuring that more important traffic is given priority over less important traffic. In this scenario, the engineer is configuring QoS for a 100 Mb WAN link, where an ISP SLA was signed to support 70% of the link.
Option A: "traffic-shape rate 100000000 70000000 70000000" This command shapes traffic to 100 Mbps, but limits it to 70 Mbps, which is what the SLA specifies. However, this command does not maintain a steady flow. By limiting traffic to 70 Mbps, this command can result in traffic being held back, leading to traffic bursts, and potentially causing delays in traffic delivery.
Option B: "police cir 70000000 confirm-action transmit exceed-action drop 243" This command limits traffic to 70 Mbps, which is what the SLA specifies. However, the "exceed-action drop" clause drops any traffic that exceeds the limit, which could cause delays in traffic delivery, leading to an unstable flow.
Option C: "police 70000000 13125000 confirm-action transmit exceed-action drop" This command sets the policing rate to 70 Mbps, which is what the SLA specifies. The "confirm-action transmit" clause allows the traffic to be transmitted if it does not exceed the specified limit. The "exceed-action drop" clause drops any traffic that exceeds the limit. However, this command does not ensure a steady flow of traffic and may result in traffic bursts.
Option D: "traffic-shape rate 70000000 8750000 8750000" This command shapes traffic to 70 Mbps, which is what the SLA specifies. The two 8750000 values in the command correspond to the Bc (committed burst) and Be (excess burst) values, respectively. Bc represents the number of bits that can be transmitted at the shaped rate, and Be represents the number of bits that can be transmitted in excess of the shaped rate. By specifying Bc and Be values, this command ensures a steady flow of traffic, preventing traffic bursts, and ensuring that traffic delivery is consistent.
In conclusion, Option D is the best QoS command to use in this scenario as it shapes traffic to the SLA's rate and ensures a steady flow of traffic.