10 Cisco Software-Defined Access Interview Questions and Answers

Cisco Software-Defined Access (SDA) represents a significant shift in network management, offering a more automated and secure approach to network design and operation. By leveraging principles of software-defined networking (SDN), SDA simplifies the creation and management of network policies, enhances security through segmentation, and provides greater visibility into network performance. This technology is particularly valuable in large-scale enterprise environments where traditional network management can become cumbersome and inefficient.

This article aims to prepare you for interviews by presenting a curated selection of questions and answers focused on Cisco SDA. By familiarizing yourself with these topics, you will gain a deeper understanding of the key concepts and practical applications of SDA, positioning yourself as a knowledgeable candidate in the field of modern network solutions.

Cisco Software-Defined Access Interview Questions and Answers

1. Explain the concept of Cisco Software-Defined Access (SD-Access) and its primary components.

Cisco Software-Defined Access (SD-Access) is part of Cisco’s Digital Network Architecture (DNA), designed to simplify and automate network operations using software-defined networking (SDN) principles. It abstracts network hardware for centralized management and policy enforcement.

The primary components of Cisco SD-Access include:

• DNA Center: The centralized platform for network visibility, policy management, and assurance.
• Fabric: The network infrastructure consisting of fabric edge nodes, control plane nodes, and border nodes, providing segmentation and policy enforcement.
• Identity Services Engine (ISE): A platform for identity-based access control and policy enforcement.
• Network Data Platform (NDP): A platform for collecting and analyzing network telemetry data.

2. Describe the role of the Cisco DNA Center in SD-Access.

Cisco DNA Center is the centralized management platform in SD-Access, offering a single interface for network administrators to design, provision, and manage their network infrastructure.

Key functionalities include:

• Network Automation: Automates configuration and deployment of network devices.
• Policy Enforcement: Facilitates creation and enforcement of network policies.
• Assurance and Analytics: Provides real-time insights and analytics for monitoring network performance.
• Segmentation: Facilitates network segmentation for enhanced security and performance.
• Integration: Integrates with other Cisco solutions and third-party applications.

3. Write a Python script to interact with the Cisco DNA Center API to retrieve a list of all devices.

To interact with the Cisco DNA Center API and retrieve a list of all devices, authenticate and make a GET request to the appropriate endpoint. Below is a Python script demonstrating this process:

import requests
import json

# Replace with your Cisco DNA Center credentials and URL
DNAC_URL = "https://sandboxdnac.cisco.com"
USERNAME = "devnetuser"
PASSWORD = "Cisco123!"

def get_auth_token():
    url = f"{DNAC_URL}/dna/system/api/v1/auth/token"
    response = requests.post(url, auth=(USERNAME, PASSWORD), verify=False)
    response.raise_for_status()
    token = response.json()["Token"]
    return token

def get_devices(token):
    url = f"{DNAC_URL}/dna/intent/api/v1/network-device"
    headers = {"X-Auth-Token": token}
    response = requests.get(url, headers=headers, verify=False)
    response.raise_for_status()
    devices = response.json()["response"]
    return devices

if __name__ == "__main__":
    token = get_auth_token()
    devices = get_devices(token)
    print(json.dumps(devices, indent=2))

4. Describe the process of onboarding a new device into an SD-Access fabric.

Onboarding a new device into an SD-Access fabric involves several steps:

• Device Discovery and Identification: The device is discovered using protocols like Cisco Discovery Protocol (CDP) or Link Layer Discovery Protocol (LLDP) and authenticated.
• Device Provisioning: The device is provisioned with necessary configurations, assigned to a virtual network (VN), and policies are applied.
• Fabric Integration: The device is configured to participate in the fabric control and data planes, assigned a fabric role.
• Policy Application: Policies are applied to control traffic flow and enforce security.
• Verification and Monitoring: The device’s functionality within the fabric is verified, and continuous monitoring ensures it remains operational and secure.

5. Explain the concept of a “fabric” in SD-Access and its significance.

In SD-Access, a “fabric” is a network architecture that simplifies, automates, and secures enterprise networks. It virtualizes the network infrastructure, enabling consistent policy enforcement and segmentation.

The significance of the fabric includes:

• Automation: Reduces manual intervention and potential errors.
• Segmentation: Enables micro-segmentation for enhanced security.
• Policy Consistency: Ensures consistent policy application across the network.
• Scalability: Designed to scale easily with network growth.
• Enhanced Security: Provides a secure environment by abstracting the physical network.

6. Discuss the challenges and limitations of implementing SD-Access in a large enterprise network.

Implementing SD-Access in a large enterprise network presents challenges:

Complexity: Transitioning from a traditional network to SD-Access requires understanding both existing infrastructure and new components, leading to a learning curve.

Cost: Initial costs include new hardware, software licenses, and training, which can be significant for large enterprises.

Integration: Integrating SD-Access with existing infrastructure and third-party systems can be challenging due to compatibility issues.

Scalability: Ensuring the solution can handle large-scale performance requirements requires careful planning.

Security: Transitioning involves rethinking security architecture to integrate enhanced features.

7. How can automation be leveraged in SD-Access to improve network management?

Automation in SD-Access improves network management by streamlining tasks:

• Policy Enforcement: Ensures consistent and dynamic policy application.
• Network Provisioning: Enables rapid deployment of devices and services.
• Monitoring and Troubleshooting: Continuously monitors performance and resolves issues automatically.
• Security: Responds to threats by adjusting configurations and policies.
• Scalability: Facilitates network scaling with minimal manual intervention.

8. What methods are used for performance monitoring in an SD-Access environment?

Performance monitoring in an SD-Access environment involves several methods:

• Telemetry: Collects real-time data from network devices.
• Analytics: Processes telemetry data for actionable insights.
• Cisco DNA Center: Provides comprehensive monitoring capabilities.
• NetFlow: Collects IP traffic information for understanding patterns.
• SNMP: Collects and organizes information about managed devices.

9. How does SD-Access impact end-user experience?

SD-Access impacts end-user experience by providing a secure, efficient, and seamless network environment.

Key impacts include:

• Improved Security: Uses micro-segmentation to reduce the attack surface.
• Enhanced Performance: Optimizes traffic flows for reduced latency.
• Consistent Policy Enforcement: Ensures uniform experience across the network.
• Seamless Mobility: Allows users to move without disruptions.
• Simplified Troubleshooting: Provides visibility for quick issue resolution.

10. Write a Python script to monitor the health of the SD-Access fabric using the Cisco DNA Center API.

To monitor the health of the SD-Access fabric using the Cisco DNA Center API, use the following Python script. It authenticates with the Cisco DNA Center, retrieves the health status, and prints the information.

import requests
import json

# Disable warnings for insecure connections
requests.packages.urllib3.disable_warnings()

# Cisco DNA Center credentials and URL
DNAC_URL = "https://your-dnac-url"
USERNAME = "your-username"
PASSWORD = "your-password"

# Function to get the authentication token
def get_auth_token():
    url = f"{DNAC_URL}/dna/system/api/v1/auth/token"
    response = requests.post(url, auth=(USERNAME, PASSWORD), verify=False)
    response.raise_for_status()
    token = response.json()["Token"]
    return token

# Function to get the health of the SD-Access fabric
def get_fabric_health(token):
    url = f"{DNAC_URL}/dna/intent/api/v1/site-health"
    headers = {"X-Auth-Token": token}
    response = requests.get(url, headers=headers, verify=False)
    response.raise_for_status()
    return response.json()

# Main function
if __name__ == "__main__":
    token = get_auth_token()
    fabric_health = get_fabric_health(token)
    print(json.dumps(fabric_health, indent=2))