[DAY#8 PyATS Series] Parsing show version on Cisco/Arista/Palo Alto/Fortigate (Ping Tests) Using pyATS (Vendor-Agnostic) [Python for Network Engineer]

Introduction: Why Parsing show version Matters in Multi-Vendor Networks

When it comes to validating OS versions, uptime, model information, and license status across multiple vendors, the show version command remains a universal checkpoint. Whether you’re managing Cisco routers, Arista switches, Palo Alto firewalls, or FortiGate appliances, parsing this command automatically can give you a huge productivity and consistency boost. And that’s exactly what we’re learning today using pyATS + Genie parsers in a vendor-agnostic way.

If you’re an aspiring Python for Network Engineer professional, this blog series is your structured journey through the real-world use cases of pyATS. Today’s article teaches you how to run show version and parse it automatically across Cisco, Arista, Palo Alto, and Fortinet devices with a single click.

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Topology Overview

In our lab, we’ve connected a set of network devices with management access enabled via SSH:

• Cisco IOS XE Router (R1)
• Arista EOS Switch (A1)
• Palo Alto NGFW (PA1)
• FortiGate Firewall (FG1)

We’ll validate:

• Uptime
• Software version
• Hostname
• Serial number
• Model/platform

Using one centralized Python script via pyATS, regardless of the underlying vendor syntax.

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Why Vendor-Agnostic Testing Matters

In real-world enterprise and service provider networks, it’s rarely a single-vendor environment. Today, the average network includes:

• Cisco routers and switches
• Arista leaf-spine data centers
• Palo Alto firewalls at the edge
• FortiGate devices for branch security

This makes manual validation slow, repetitive, and error-prone. A change in one vendor’s OS syntax can break scripts that aren’t abstracted.

That’s where vendor-agnostic testing with pyATS and Genie shines:

• Unified framework
• Extensible CLI parsers
• Automated ping and version checks
• Simplified testing pipelines

We focus on reliability, consistency, and reusability across platforms.

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Topology & Communications

All devices are reachable over SSH with login credentials stored in the testbed.yml.

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Workflow Script: parse_show_version.py

from genie.testbed import load
import json

# Load the testbed
testbed = load('testbed.yml')

# List of devices
devices = ['r1', 'a1', 'pa1', 'fg1']

# Result dictionary
results = {}

for dev_name in devices:
    device = testbed.devices[dev_name]
    print(f" Connecting to {device.name}...")
    device.connect(init_exec_commands=[], init_config_commands=[], log_stdout=False)

    # Execute and parse show version
    try:
        output = device.parse('show version')
        results[device.name] = output
    except Exception as e:
        print(f" Error parsing {device.name}: {e}")
        results[device.name] = str(e)

    device.disconnect()

# Pretty print the parsed results
print(json.dumps(results, indent=2))

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Explanation by Line

Line	Explanation
from genie.testbed import load	Imports pyATS testbed parser
testbed = load('testbed.yml')	Loads YAML file with device credentials
devices = [...]	List of device names defined in the testbed
device.connect()	Establishes SSH connection
device.parse('show version')	Runs the command and parses using Genie
results[...] = output	Stores parsed result in dictionary
json.dumps(...)	Converts Python dict to pretty JSON format

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testbed.yml Example

testbed:
  name: show_version_lab
  credentials:
    default:
      username: admin
      password: cisco123

devices:
  r1:
    os: iosxe
    type: router
    connections:
      defaults:
        class: unicon.Unicon
      cli:
        protocol: ssh
        ip: 10.1.1.1

  a1:
    os: eos
    type: switch
    connections:
      defaults:
        class: unicon.Unicon
      cli:
        protocol: ssh
        ip: 10.1.1.2

  pa1:
    os: panos
    type: firewall
    connections:
      defaults:
        class: unicon.Unicon
      cli:
        protocol: ssh
        ip: 10.1.1.3

  fg1:
    os: fortinet
    type: firewall
    connections:
      defaults:
        class: unicon.Unicon
      cli:
        protocol: ssh
        ip: 10.1.1.4

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Multi‑Vendor CLI Screenshots (Parsed Outputs)

Cisco Output

"r1": {
  "version": "17.6.4",
  "uptime": "1 week",
  "hostname": "R1",
  "serial_number": "FTX1234X1AB",
  "model": "ISR4431/K9"
}

Arista Output

"a1": {
  "version": "4.28.1F",
  "hostname": "A1",
  "modelName": "DCS-7050SX3-48YC12",
  "uptime": "3 days"
}

Palo Alto Output

"pa1": {
  "sw_version": "10.1.4",
  "model": "PA-220",
  "uptime": "5 days",
  "hostname": "PA1"
}

FortiGate Output

"fg1": {
  "version": "v7.0.5",
  "hostname": "FG1",
  "serial": "FGT60FTK12345678",
  "uptime": "2 days"
}

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FAQs

Q1. Can Genie parse commands from non-Cisco devices?

Yes, Genie supports other platforms via community parsers or custom Python logic. It natively supports Cisco platforms, while PAN-OS and FortiOS need either regex or custom parser extensions.

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Q2. What happens if a device doesn’t support show version?

The script will catch exceptions and return an error message like command not recognized or parser not available, helping you to identify unsupported cases.

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Q3. How to extend this to export results into a CSV or Excel?

You can use pandas.DataFrame.from_dict(results).to_csv("output.csv") after parsing to export structured data.

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Q4. Can this be integrated into CI/CD pipelines?

Absolutely. You can integrate the script with Jenkins, GitHub Actions, or any other CI/CD tool to validate device OS versions post-deployment.

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Q5. Will this work if SSH is disabled?

No. pyATS requires network access and SSH/console connectivity. You can use mock devices for dry runs in lab environments.

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Q6. Is there a way to visually compare OS versions?

Yes, you can add logic to color-code versions or compare them against a baseline matrix to check for outdated firmware.

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Q7. How do I create a custom parser for a vendor not natively supported?

Use genie.parsergen, regex, or extend base classes to create and register a custom parser within your pyATS environment.

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Q8. Can we add ping test post validation?

Definitely! Just add device.ping(destination) after parsing to test end-to-end reachability and loopback connectivity.

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YouTube Link

Watch the Complete Python for Network Engineer: Parsing show version on Cisco/Arista/Palo Alto/Fortigate (Ping Tests) Using pyATS (Vendor-Agnostic) Lab Demo & Explanation on our channel:

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Join Our Training

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You’ll go from zero to production-ready skills with practical lab exercises, use cases, and automation pipelines.

• Starts every month
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