“I spent four hours on a Saturday night manually logging into 40 Cisco routers via PuTTY to change a single NTP server address. I swore I would never do that again.”

In early 2017 at Wipro, I recognized that manual CLI interaction was the single largest bottleneck in enterprise network engineering.

I shifted my focus from manual terminal commands to Python Network Automation, leveraging libraries like netmiko and paramiko.

The Paradigm Shift: Scripting Network Tasks

Instead of opening multiple terminal windows, I wrote a multi-threaded Python script that established SSH sessions concurrently across 50 devices, parsed output strings, and validated configurations.

# # Concurrent Cisco IOS Configuration Update via Netmiko
from netmiko import ConnectHandler
import concurrent.futures

devices = [
    {'device_type': 'cisco_ios', 'host': '10.1.1.1', 'username': 'admin', 'password': 'Secr3tPassword'},
    {'device_type': 'cisco_ios', 'host': '10.1.1.2', 'username': 'admin', 'password': 'Secr3tPassword'}
]

def update_ntp(device):
    net_connect = ConnectHandler(**device)
    config_commands = ['ntp server 10.100.1.50', 'clock timezone UTC 0']
    output = net_connect.send_config_set(config_commands)
    net_connect.disconnect()
    return f"Completed on {device['host']}"

with concurrent.futures.ThreadPoolExecutor() as executor:
    results = executor.map(update_ntp, devices)
    for res in results:
        print(res)

[!NOTE] Netmiko: A specialized Python library built on top of Paramiko that handles SSH connection maintenance, prompt waiting, and configuration mode handling for multi-vendor network operating systems.

The Verdict

Key Takeaway

Automate Repetitive Tasks Immediately.

If you execute a CLI task manually more than twice, write a script. Learning Python for Network Automation shifts your engineering role from manual operator to systems architect.