Network Automation for Beginners — Python, Ansible and Cisco DevNet

Why Automation Matters Now

Five years ago, automation was a nice-to-have skill for network engineers. Today, it is a differentiator that determines whether your salary stays at Rs 6 LPA or reaches Rs 20 LPA. Job postings at Amazon, Cisco, and large telcos routinely list Python or Ansible as requirements — not preferences — for mid-level networking roles.

This does not mean you need to become a software developer. It means you need to be able to write a 30-line Python script that SSH-es into 50 routers and checks interface status — a task that previously took an hour of manual work.

The Automation Stack — What to Learn and in What Order

• Step 1 — Python basics (3–4 weeks): Variables, data types, loops, functions, file I/O, and basic error handling. You do not need object-oriented programming for networking automation at this level.
• Step 2 — Netmiko (2–3 weeks): Netmiko is a Python library that simplifies SSH connections to network devices. It supports Cisco IOS, IOS-XE, IOS-XR, NX-OS and 30+ other platforms. With Netmiko, you can push configuration changes to hundreds of devices in minutes.
• Step 3 — NAPALM (1–2 weeks): NAPALM (Network Automation and Programmability Abstraction Layer with Multivendor support) provides a vendor-agnostic API for common network tasks. Write one script that works on Cisco, Juniper and Arista without changing the logic.
• Step 4 — Ansible for networking (2–4 weeks): Ansible uses YAML playbooks to describe network state. It is agentless (no software on the device), idempotent (safe to run repeatedly), and integrates with version control (Git). The Cisco-supported Ansible modules cover IOS, NX-OS, ASA and DNA Center.
• Step 5 — REST APIs and Cisco DNA Center (2–3 weeks): Modern Cisco infrastructure exposes REST APIs. Learning to query DNA Center's API with Python opens up intent-based networking automation — automatically configuring network policies based on business intent.

A Real Automation Example — Pulling Interface Stats

Instead of logging into 20 routers one by one to check interface utilisation, a Netmiko script can do this in 2 minutes:

from netmiko import ConnectHandler

devices = [
    {"device_type": "cisco_ios", "host": "192.168.1.1",
     "username": "admin", "password": "cisco123"},
]

for device in devices:
    conn = ConnectHandler(**device)
    output = conn.send_command("show interfaces summary")
    print(f"--- {device['host']} ---")
    print(output)
    conn.disconnect()

This is the entry point — once you can do this, adding error handling, logging to a file, and emailing a report takes another 20 lines.

Cisco DevNet — The Automation Certification Path

Cisco's DevNet certification track validates automation skills formally. The DevNet Associate (200-901 DEVASC) is the entry-level exam, covering Python, REST APIs, Cisco DNA Center, Webex APIs, and infrastructure-as-code concepts. It pairs well with CCNA or CCNP.

The free resources at developer.cisco.com — including interactive sandboxes where you can call real Cisco APIs — are the best place to start learning.

How Much Automation Will Your Job Actually Require?

At the L1 NOC level — almost none. At L2 (3–5 years) — you will be expected to at least read and modify scripts written by others. At the senior/architect level — you will be expected to design automation workflows and evaluate tools like Ansible Tower or Cisco NSO.

Starting automation learning early — even as a CCNA student — gives you a compounding advantage. Engineers who wait until they need it find themselves spending months catching up while their peers are getting promoted.

Frequently Asked Questions