Control Plane Policing (CoPP) on Cisco Nexus 9000
Which TWO statements are true about Control Plane Policing (CoPP) on a Cisco Nexus 9000 switch? (Choose two.)
Quick Answer
The correct answer is that CoPP is configured using the 'control-plane' sub-mode with policy-maps, and it can rate-limit control-plane traffic such as ICMP unreachable messages. This works because Control Plane Policing on a Nexus 9000 switch uses a modular QoS CLI (MQC) approach: you define class-maps to match specific control-plane protocols, then apply a policy-map with a police action under the 'control-plane' sub-mode to limit the rate of those packets, protecting the CPU from floods. On the Cisco DCCOR 350-601 exam, this topic tests your understanding of how to safeguard the supervisor engine from denial-of-service attacks without disrupting legitimate traffic—a common trap is confusing CoPP with hardware rate-limiters or thinking it applies to data-plane forwarding. Remember the memory tip: "CoPP cops the control plane, not the data plane," meaning you always apply the policy under 'control-plane' and never under a physical interface.
⚠ Common exam trap
Cisco often tests the misconception that CoPP is only for management IP traffic or that it can prioritize traffic, when in fact it is a policing mechanism for all control-plane traffic and does not provide prioritization.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
CoPP can be used to limit the rate of ICMP unreachable messages.
CoPP can rate-limit control-plane traffic such as ICMP unreachable messages. By applying a policy-map in the 'control-plane' sub-mode, you can define class-maps that match specific control-plane protocols (e.g., ICMP) and then police their rate to prevent CPU overload from floods of such packets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
CoPP can be used to limit the rate of ICMP unreachable messages.
Why this is correct
ICMP unreachable messages can be rate-limited with CoPP to prevent DoS.
- ✗
CoPP automatically drops all unknown unicast traffic.
Why it's wrong here
Unknown unicast flooding is controlled by other features, not CoPP.
- ✓
CoPP is configured using the 'control-plane' sub-mode with policy-maps.
Why this is correct
CoPP is configured by creating a policy-map and applying it under the 'control-plane' configuration mode.
- ✗
CoPP applies only to traffic destined to the switch management IP.
Why it's wrong here
CoPP protects the entire control plane, including routing protocol traffic, not just management IP.
- ✗
CoPP can be used to prioritize OSPF traffic over SSH.
Why it's wrong here
CoPP polices (limits) traffic, but prioritization is achieved with QoS, not CoPP.
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Same concept, more angles
2 more ways this is tested on 350-601
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An engineer needs to secure the management plane on a Cisco Nexus 9000 switch. Which feature should be configured to restrict access to the switch's management interface based on source IP?
easy- A.Enable DHCP snooping on the management VLAN.
- B.Enable port security on the management interface.
- C.Configure AAA to require two-factor authentication.
- ✓ D.Configure a management CoPP policy to rate-limit and permit only specific source IPs.
Why D: A management Control Plane Policing (CoPP) policy on a Cisco Nexus 9000 switch allows the engineer to explicitly permit or deny traffic destined to the management interface based on source IP addresses. CoPP applies QoS policies to control plane traffic, effectively restricting management plane access by rate-limiting or dropping packets from unauthorized sources before they reach the CPU.
Variation 2. Refer to the exhibit. The CoPP policy above is applied. Which traffic is most likely to be dropped?
hard- A.Both ICMP and class-default traffic that exceed their rates
- ✓ B.ICMP traffic that exceeds 1000 bps
- C.class-default traffic that exceeds 20000 bps
- D.OSPF traffic that exceeds 5000 bps
Why B: The CoPP policy explicitly defines a class-map for ICMP traffic with a police rate of 1000 bps. Any ICMP traffic exceeding this rate is dropped due to the 'drop' action in the police command. The other classes (OSPF and class-default) have higher rates and are not as constrained, making ICMP the most likely to be dropped when exceeded.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-601 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-601 exam.