Multi-Vendor Network Automation with Paramiko, Netmiko, NAPALM, and Ansible

🔧 Tools Overview

🔹 Paramiko – Low-level SSH automation

How it works:

• Uses Python to establish a raw SSH connection (SSHClient())
• Opens a shell session (invoke_shell())
• Sends commands as if you’re typing them manually, line by line
• Requires manual timing (e.g., time.sleep) and careful prompt handling

Why use it:

• Full control of SSH, useful when:
  • Devices don’t support Netmiko/NAPALM
  • You need to emulate real user input
  • Automating Linux systems or non-network devices

Deep insight:

• Paramiko is like remote-controlling a terminal.
• Doesn’t parse output — you must know exactly what the device will return.
• No abstraction. You manually handle prompts, delays, and formatting.

🔹 Netmiko – Network CLI automation

How it works:

• Built on top of Paramiko
• Adds device-type support (cisco_ios, juniper, etc.)
• Handles login, enable mode, config mode, command prompts automatically
• Provides send_command() and send_config_set() helpers

Why use it:

• Automate CLI-based network devices safely and quickly
• Reliable command execution without writing timing logic
• Ideal for one-time setups or scripting lab configs

Deep insight:

• Netmiko is like CLI with training wheels.
• Great for engineers familiar with CLI — use same commands, just automated.

🔹 NAPALM – Structured API-style config for routers

How it works:

• Uses vendor-specific APIs (NETCONF, RESTCONF, SSH)
• Loads config as structured blocks (like set interfaces ...)
• Shows config diffs before committing
• Supports rollback and multi-vendor support

Why use it:

• Safe, repeatable, and structured configuration
• Enables config comparison, preview, commit like Git
• Great for production, CI/CD, or version-controlled environments

Deep insight:

• NAPALM isn’t about command execution — it’s about state configuration
• You describe what you want; NAPALM makes it happen safely and consistently

🔹 Ansible – Agentless, YAML-based automation framework

How it works:

• Uses SSH (or APIs) to push configuration or run modules
• Reads from inventory files and YAML playbooks
• Uses collections like cisco.ios, arista.eos, etc.
• Stateless execution – every run enforces the desired state

Why use it:

• Manage multiple devices at once
• Readable, reusable, scalable automation
• Excellent for infrastructure-as-code, compliance, GitOps

Deep insight:

• Ansible is declarative — describe what the device should look like
• Not limited to networking — automate cloud, Linux, containers, and more
• Best for large environments or teams needing repeatability and auditability

This project demonstrates full network automation for a multi-vendor lab using three Python libraries: Paramiko, Netmiko, and NAPALM. The network topology includes:

• 3 Routers:
  • Cisco IOS
  • Arista EOS
  • Juniper JunOS
• 1 Cisco Layer 2 Switch
• 1 Linux-based NAT Gateway (NAT1)

Each device is configured via a dedicated script that matches its capabilities.

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📈 Network Topology

+----------+        +----------+        +----------+
| Cisco R1 |<----->| Arista R2 |<----->| Juniper R3|
+----------+        +----------+        +----------+
     |                   |                  |
     |                   |                  |
     +--------+   +------+-------+   +------+
              |   | Cisco Switch |   |           
              +---+   VLAN Core  +---+             
                  +-------------+   
                         |
                    +---------+
                    |  NAT1   |
                    +---------+

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📅 Folder Structure

network-automation-project/
├── paramiko_config.py         # Arista + Juniper + Cisco via Paramiko
├── netmiko_config.py          # Cisco + Switch + NAT via Netmiko
├── napalm_config.py           # Cisco + Arista + Juniper via NAPALM
├── ansible/
│   ├── hosts.yaml             # Ansible inventory for switch
│   └── vlan_config.yaml       # Ansible playbook for VLAN config
├── requirements.txt           # Python dependencies
├── network_topology.png       # (Optional) Visual Diagram
└── README.md                  # This file

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📖 Tools & Libraries Used

Tool	Purpose
Paramiko	SSH automation (low-level)
Netmiko	Simplified CLI automation
NAPALM	Multi-vendor, API-style config
Ansible	YAML-based config management

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🔧 Configuration Summary

Device	OS	IP	Library Used
Cisco Router	Cisco IOS	192.168.122.10	Netmiko / NAPALM / Paramiko
Arista Router	Arista EOS	192.168.122.30	Paramiko / NAPALM
Juniper Router	Juniper OS	192.168.122.20	Paramiko / NAPALM
Switch	Cisco IOS	192.168.122.50	Netmiko / Ansible
NAT1 Gateway	Linux	192.168.122.1	Netmiko

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💡 What Each Script Does

1. paramiko_config.py

• Sends CLI commands to:
  • Cisco (if required)
  • Arista
  • Juniper
• Uses invoke_shell() to simulate human SSH interaction
• Example: IP addressing, hostname, static routes

2. netmiko_config.py

• Automates:
  • Cisco IOS router interfaces and routing
  • Cisco Switch VLANs and port settings
  • NAT1 IP configuration and IP forwarding (Linux CLI)

3. napalm_config.py

• API-style configuration for:
  • Cisco IOS (interface + route)
  • Arista EOS (multi-interface + static route)
  • Juniper JunOS (interface + static route)
• Shows config differences and commits only changes

4. ansible/vlan_config.yaml

• Uses Ansible + cisco.ios collection to:
  • Create VLANs (10 = HR, 20 = TECH, 30 = FIN)
  • Assign access ports on Cisco Switch (Ethernet0–2)

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🔁 Command Execution

Python scripts:

python3 paramiko_config.py
python3 netmiko_config.py
python3 napalm_config.py

Ansible Playbook:

ansible-playbook -i ansible/hosts.yaml ansible/vlan_config.yaml

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📦 Expected Results

• Routers: Hostname, IPs, and routes to NAT1
• Switch:
  • VLAN 10 → Ethernet0 → Cisco
  • VLAN 20 → Ethernet1 → Arista
  • VLAN 30 → Ethernet2 → Juniper
• NAT1: IP set, IP forwarding enabled, NAT active

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⚠️ Troubleshooting Tips

• Use ping, show ip route, show vlan brief, or show run
• On Linux NAT, check with ip a and iptables -t nat -L
• Use -vvv in Ansible for verbose debugging

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🌟 Future Improvements

• VLAN trunking automation
• DHCP configuration via Netmiko/Ansible
• YAML-driven modular configs
• Inventory-driven dynamic templates

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📚 References

• Netmiko Docs
• NAPALM Docs
• Paramiko Docs
• Ansible Cisco IOS

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🚀 Author

Jeevanandh Ravi – Network Engineer & Automation Enthusiast

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Happy Automating! 🚀📊