Mastering Control Plane Policing (CoPP) for the CCNP 350-401 ENCOR Exam

Mastering Control Plane Policing (CoPP) for the CCNP 350-401 ENCOR Exam

If you’re prepping for the CCNP 350-401 ENCOR exam, you’re probably swimming in acronyms, protocols, and various network control mechanisms. One topic that might trip you up is Control Plane Policing (CoPP). Let’s not kid ourselves – CoPP can be a bit of a labyrinth. But fear not! By the end of this blog post, you'll have a firm grasp of what CoPP is and why it’s a crucial part of your networking toolkit.

What is Control Plane Policing (CoPP)?

Alright, first things first. CoPP stands for Control Plane Policing. It’s essentially a mechanism within a router that allows you to control the traffic destined for the router’s control plane. Now, why is that important, you ask? Let me paint you a picture.

Imagine your router as a busy traffic cop at a bustling intersection. The control plane is the brain of this cop. Without any regulation, the sheer volume of cars (network traffic) can overwhelm our cop, causing chaos and traffic jams (network slowdowns or crashes). CoPP steps in like an elite team of traffic controllers, ensuring that our cop can focus on the most critical tasks without getting bogged down.

Why CoPP Matters in Networking

The heart of the matter lies in network performance and security. In the absence of proper control, unwanted or malicious traffic can flood the control plane. This congestion can degrade the performance or even render the router inoperable. CoPP helps mitigate this risk by filtering and policing traffic, allowing only legitimate and necessary packets to reach the control plane.

Components of CoPP

To truly ace the CCNP 350-401 ENCOR exam, you need to understand the nuts and bolts of CoPP. Here are the key components:

Class Maps

Class maps are used to classify traffic. In the context of CoPP, class maps identify the types of traffic that need specific handling, such as management traffic, routing protocol updates, and other essential control plane communications. Basically, you're setting up categories for your router to recognize.

Policy Maps

Once you've classified the traffic, you'll need to define actions using policy maps. Think of policy maps as the rulebook. They dictate what happens with the classified traffic – whether it's permitted, dropped, or rate-limited.

Service Policies

Lastly, service policies bind the class maps and policy maps to an interface. This step essentially puts your traffic rules into action. It’s like giving your router a set of instructions on how to handle traffic entering its control plane.

Configuring CoPP: A Guided Tour

Let’s roll up our sleeves and get into the nitty-gritty of setting up CoPP on a Cisco router. You’ll need access to your router’s command-line interface (CLI) for this.

Step 1: Define Class Maps

First, define the class maps to categorize the traffic. For instance:

class-map match-any MGMT-TRAFFIC
 match protocol snmp
 match protocol ssh
 match protocol telnet

In this example, we’ve created a class map named MGMT-TRAFFIC to capture SNMP, SSH, and Telnet traffic.

Step 2: Create Policy Maps

Next, set up the policy map to outline the actions:

   police 32000 conform-action transmit exceed-action drop

This policy map named CONTROL-PLANE-POLICY specifies that for management traffic, packets conforming to 32 kbps should be transmitted, while anything exceeding that is to be dropped.

Step 3: Apply Service Policies

Finally, apply the service policy to the control plane:

 service-policy input CONTROL-PLANE-POLICY

Voila! You've just configured CoPP on your router.

Verifying and Monitoring CoPP

No configuration is complete without verification. To ensure your CoPP settings are working as expected, you’d use the following command:

show policy-map control-plane

This command provides a summary of the policy maps applied to the control plane and the actions taken on matching traffic. It’s like a health check for your traffic management rules.

Advanced CoPP Configuration

Once you get comfortable with the basics, you might need to dive into more complex setups. Advanced CoPP configurations can include multiple class maps and hierarchical policy maps to cater to complex network environments. Here's a quick glance:

class-map match-all ROUTING-TRAFFIC
 match protocol ospf
 match protocol bgp

   police 64000 conform-action transmit exceed-action drop
   police 32000 conform-action transmit exceed-action drop

In this example, we’ve added another class map for routing traffic and included it in a more advanced policy map. With this setup, you can fine-tune how different types of traffic are handled, ensuring optimal control plane performance.

Common Pitfalls and Gotchas

Beware of a few common pitfalls when working with CoPP. Misconfigurations can lead to unintended traffic drops or allow through malicious packets. Always double-check your class maps and policy maps, ensuring they accurately represent the traffic you wish to control.

Best Practices for Implementing CoPP

To implement CoPP effectively, follow these best practices:

  • Start with a baseline configuration: Understand your network traffic patterns before creating CoPP rules. Capturing baseline traffic data can help you set appropriate thresholds.
  • Iterate and adjust: Implementing CoPP is not a set-it-and-forget-it task. Regularly review and update your policies based on traffic analysis and evolving network conditions.
  • Monitor consistently: Use the show policy-map control-plane command and other monitoring tools to keep tabs on control plane activities and ensure CoPP is operating as intended.
  • Document configurations: Keep a detailed record of your CoPP configurations and the rationale behind them. This practice aids troubleshooting and future adjustments.

Real-World Applications of CoPP

Control Plane Policing is not just an exam topic; it’s a real-world necessity. Consider scenarios such as Distributed Denial of Service (DDoS) attacks. Malicious actors often target the control plane to disrupt network operations. With CoPP, you can limit the amount of potentially harmful traffic to manageable levels, preserving the network's integrity.

Another critical application is in enterprise networks where management and routing traffic must be safeguarded. By classifying and policing such traffic, CoPP ensures that vital control plane operations continue unhindered, keeping the network stable and responsive.


Control Plane Policing might seem daunting at first, but with a bit of practice and a solid understanding, it becomes another valuable tool in your networking arsenal. As you prepare for the CCNP 350-401 ENCOR exam, take the time to get hands-on with CoPP configurations and monitoring. Not only will it boost your exam readiness, but it will also enhance your real-world networking skills.

So, roll up your sleeves, dive into those CLI commands, and take control (pun intended) of your CoPP configurations. Your router – and your future network – will thank you for it!