Question 472 of 2,152
Control Plane Policing (CoPP)mediumMultiple ChoiceObjective-mapped

CoPP Match Protocol Limitation

This 300-410 practice question tests your understanding of control plane policing (copp). The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Consider the following CoPP configuration:

class-map match-any COPP-ROUTING match protocol ospf match protocol eigrp match protocol bgp ! policy-map COPP-POLICY

class COPP-ROUTING

police 32000 conform-action transmit exceed-action drop

class class-default

police 64000 conform-action transmit exceed-action drop ! control-plane service-policy input COPP-POLICY

What is a potential issue with this configuration?

Quick Answer

The answer is that the configuration is invalid because the match protocol command is not supported in CoPP class-maps, which creates a CoPP match protocol limitation. CoPP operates at the control plane level and can only classify traffic using Access Control Lists (ACLs) or DSCP/IP precedence values, not by protocol names like OSPF, EIGRP, or BGP. This means the policy-map will fail to correctly identify and police routing protocol traffic, leaving the control plane unprotected. On the Cisco CCNP ENARSI 300-410 exam, this tests your understanding of CoPP’s classification constraints—a common trap is assuming that match protocol works universally, when in fact it is only valid for QoS policies on data-plane interfaces. Remember the memory tip: “CoPP cops only ACLs and DSCP, not protocol names.”

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

The 'match protocol' command is not supported in CoPP class-maps; only ACLs or DSCP/IP precedence can be used.

Option C is correct because the 'match protocol' command is not supported in Control Plane Policing (CoPP) class-maps. CoPP operates on the control plane, which processes packets that are destined to the router itself; these packets are typically identified by ACLs, DSCP, or IP precedence values, not by protocol names like OSPF, EIGRP, or BGP. The 'match protocol' command is used in QoS policies applied to data-plane interfaces, not in control-plane service policies.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • The class-map uses match-any instead of match-all, which will cause incorrect matching.

    Why it's wrong here

    Incorrect. Both match-any and match-all are valid; match-any is actually appropriate here if multiple protocols should be matched individually.

  • The police rate of 32000 bps is too low for routing protocol traffic and may cause adjacency drops.

    Why it's wrong here

    Incorrect. While the rate might be low, the primary issue is the use of match protocol.

  • The 'match protocol' command is not supported in CoPP class-maps; only ACLs or DSCP/IP precedence can be used.

    Why this is correct

    Correct. CoPP only supports match access-group, match ip dscp, or match ip precedence. match protocol is not allowed.

    Related concept

    Read the scenario before looking for a memorised answer.

  • The policy-map must be applied to the control-plane with the 'output' keyword instead of 'input'.

    Why it's wrong here

    Incorrect. CoPP can be applied as input or output; input is correct for policing incoming control-plane traffic.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the misconception that 'match protocol' can be used in CoPP class-maps because it is valid in data-plane QoS policies, but CoPP explicitly requires ACLs, DSCP, or IP precedence for classification.

Trap categories for this question

  • Command / output trap

    Incorrect. CoPP can be applied as input or output; input is correct for policing incoming control-plane traffic.

Detailed technical explanation

How to think about this question

CoPP uses Modular QoS CLI (MQC) but restricts match criteria to those that can be evaluated on packets destined to the router's control plane, such as ACLs (matching IP, port, protocol fields), DSCP, or IP precedence. The 'match protocol' command relies on Network-Based Application Recognition (NBAR), which performs deep packet inspection on transit traffic and is not designed for control-plane packets that are already terminated locally. In real-world scenarios, you would use an ACL to match routing protocol packets by their IP protocol numbers (e.g., OSPF = 89, EIGRP = 88, BGP = TCP port 179) and apply that ACL in the CoPP class-map.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.

Visual reference

R1 R2 R3 R4 10 100 10 100 OSPF picks R1→R2→R4 (cost 20) over R1→R3→R4 (cost 200)

Quick reference

Routing Protocol Comparison

ProtocolMetricMax HopsAlgorithmType
RIP v2Hop count15Bellman-FordDistance vector
OSPFCost (bandwidth)UnlimitedDijkstra (SPF)Link state
EIGRPComposite metricUnlimitedDUALHybrid
IS-ISCostUnlimitedDijkstraLink state
BGPPolicy / attributesUnlimitedPath vectorPath vector

RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this 300-410 question test?

Control Plane Policing (CoPP) — This question tests Control Plane Policing (CoPP) — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The 'match protocol' command is not supported in CoPP class-maps; only ACLs or DSCP/IP precedence can be used. — Option C is correct because the 'match protocol' command is not supported in Control Plane Policing (CoPP) class-maps. CoPP operates on the control plane, which processes packets that are destined to the router itself; these packets are typically identified by ACLs, DSCP, or IP precedence values, not by protocol names like OSPF, EIGRP, or BGP. The 'match protocol' command is used in QoS policies applied to data-plane interfaces, not in control-plane service policies.

What should I do if I get this 300-410 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jul 4, 2026

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