Exam 300-410 topic 1 question 59 discussion

Actual exam question from Cisco's 300-410

Question #: 59
Topic #: 1

A network administrator is troubleshooting a high utilization issue on the route processor of a router that was reported by NMS. The administrator logged into the router to check the control plane policing and observed that the BGP process is dropping a high number of routing packets and causing thousands of routes to recalculate frequently.
Which solution resolves this issue?

A. Shape the pir for BGP, conform-action set-prec-transmit, and exceed action set-frde-transmit.
B. Police the pir for BGP, conform-action set-prec-transmit, and exceed action set-clp-transmit.
C. Shape the cir for BGP, conform-action transmit, and exceed action transmit.
D. Police the cir for BGP, conform-action transmit, and exceed action transmit.

Show Suggested Answer

Suggested Answer: D 🗳️

by Carl1999 at Feb. 2, 2022, 2:12 p.m.

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Huntkey

Highly Voted 2 years, 8 months ago

I think it is called control plane POLICING and not SHAPING is because it only supports policing and not shaping. So D is correct

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[Removed]

Most Recent 10 months, 2 weeks ago

Selected Answer: D

D is correct

upvoted 1 times

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NicoF

1 year, 3 months ago

I was confused with the correct answer D, since the conform & exceed action were both set to transmit. But the QoS documentation says the exceed action transmit also sets an IPP of 4.

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ZamanR

1 year, 5 months ago

I think A Explanation CIR (Committed Information Rate) is the minimum guaranteed traffic delivered in the network. PIR (Peak Information Rate) is the top bandwidth point of allowed traffic in a non busy times without any guarantee.

upvoted 1 times

ZamanR

1 year, 5 months ago

Policing: is used to control the rate of traffic flowing across an interface. During a bandwidth exceed (crossed the maximum configured rate), the excess traffic is generally dropped or remarked. The result of traffic policing is an output rate that appears as a saw-tooth with crests and troughs. Traffic policing can be applied to inbound and outbound interfaces. Unlike traffic shaping, QoS policing avoids delays due to queuing. Policing is configured in bytes. + Shaping: retains excess packets in a queue and then schedules the excess for later transmission over increments of time. When traffic reaches the maximum configured rate, additional packets are queued instead of being dropped to proceed later. Traffic shaping is applicable only on outbound interfaces as buffering and queuing happens only on outbound interfaces. Shaping is configured in bits per second.

upvoted 2 times

ZamanR

1 year, 5 months ago

Therefore in this case we can only policing, not shaping as traffic shaping is applicable only on outbound interfaces as buffering and queuing happens only on outbound interfaces. Moreover, BGP traffic is not important so we can drop the excess packets without any problems. And we only policing the PIR traffic so that the route processor is not overwhelmed by BGP calculation Note: The “set-prec-transmit” is the same as “transmit” command except it sets the IP Precedence level as well. The “set-clp-transmit” sets the ATM Cell Loss Priority (CLP) bit from 0 to 1 on the ATM cell and transmits the packet.

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AinsB

2 years ago

Selected Answer: D

One very important concept is that Traffic shaping allows you to control the speed of traffic that is leaving an interface. This way, you can match the flow of the traffic to the speed of the interface receiving the packet. Policing works in both directions Input and Output. "Traffic policing allows you to control the maximum rate of traffic sent or received on an interface and to partition a network into multiple priority levels or class of service (CoS)."

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HungarianDish_111

2 years, 1 month ago

Selected Answer: D

This is how I see it. As Huntkey mentioned, the issue is not described as relating to ATM or Frame Relay, so we can ignore A and B. Then we we need to choose between C and D. C is for shaping, but you won't achieve shaping with the commands "conform-action transmit action-transmit", so C is not a valid solution. Excluding wrong answers, D is left.

upvoted 4 times

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