I Built a Network Engineer Gem — Here's What It Actually Does
I've spent 25 years in network infrastructure. I know this domain well. So this Gem works differently from the others I've built — I'm not using it because I lack the knowledge. I'm using it as a second opinion, a sounding board, and a way to move faster on tasks that are routine but still time-consuming.
This is the Gem I trust most, because I can actually verify whether its answers are right.
What Is a Network Engineer Gem?
It's a Gemini assistant configured as a senior network engineer with deep knowledge of routing protocols, switching architectures, security policies, and network monitoring. You describe your environment once, and it works within that context for every question.
For people without my background, it can explain network concepts clearly. For me, it works at a peer level — I can use shorthand, assume shared knowledge, and get direct answers without explanation padding.
Why I Built This Gem
Three specific use cases pushed me to build it:
- Writing and reviewing complex ACL configurations — tedious to do manually, easy to make errors
- Checking my reasoning on routing decisions before implementing them in production
- Generating documentation for network changes that I'd otherwise write from scratch
None of these required the Gem to know more than me. They required it to work accurately and fast within a context I already understood.
The Prompt I Use
Here's the core of my Gem's instructions:
You are my senior network engineer colleague with deep expertise in enterprise networking. When I ask network questions: - Work at a senior engineer level — skip introductory explanations unless I ask - Review configurations for errors, security gaps, and best practice violations - Flag anything that could cause an outage or security exposure - Generate clean configuration snippets in the format I specify - Be direct about tradeoffs — I can handle nuance My environment: enterprise LAN/WAN, Cisco IOS and NX-OS, Juniper JunOS, BGP and OSPF routing, VLAN segmentation, standard ACL security model. Primary focus: uptime and security.
The "work at a senior engineer level" instruction is the critical one. It signals to the Gem how much to assume and what to skip.
Real Examples — What I Actually Ask It
Some recent questions I've put to this Gem:
- "Here's a BGP peer configuration. Is anything missing or potentially unstable?"
- "I need an ACL that allows HTTPS and SSH inbound from this subnet and blocks everything else. Generate it for IOS syntax."
- "I'm seeing asymmetric routing between these two paths. What's the most likely cause given this topology?"
For the ACL request, it generated clean, commented IOS syntax with the exact permit/deny structure I needed, flagged that I hadn't specified whether to log denied traffic (a useful prompt), and noted one edge case I'd overlooked. That's a peer-level review, not a tutorial.
Using It for Documentation
One unexpected use I've gotten a lot of value from: change documentation. I describe the network change I'm making and ask the Gem to write the change record — what's changing, why, rollback procedure, expected impact. It produces a solid first draft in about 30 seconds that I review and adjust.
Writing change records is necessary but not something most engineers enjoy. The Gem makes it significantly faster.
What It's Good At (and Where It Falls Short)
Good at:
- Reviewing configurations for errors and best practice violations
- Generating clean configuration syntax for common tasks
- Explaining routing and switching behavior in a specific scenario
- Drafting change documentation and runbooks
Where it falls short:
- It doesn't have access to your actual network unless you paste configs in
- For vendor-specific edge cases or bugs, official documentation and TAC are more reliable
- Real network state (interface counters, routing tables) requires actual access to devices
Try It Yourself — Starter Prompt
If you want to build a similar Gem, here's a starting point:
You are my senior network engineer colleague. Review configurations for errors and security gaps. Generate configuration syntax when I ask. Flag anything that could cause an outage or security exposure. Work at the level I specify. My environment: [your vendors, protocols, primary focus areas]
Paste this into a new Gem at gemini.google.com, add your environment details, and test it with a real configuration snippet you have on hand.
- Series Overview: Gems vs GPTs vs Claude Projects
- Previous: My Personal Developer Gem
- You are here: My Network Engineer Gem
- Next: My Apple Device Expert Gem (coming soon)
Related Posts
- Gemini Gems vs. ChatGPT GPTs vs. Claude Projects — How these custom AI tools compare before you build your first one
- My DNS Expert Gem — A narrower companion Gem that handles DNS-specific questions in depth
- Is AI Safe to Use? Privacy and Security Guide — What to know before sharing network configurations with an AI
Sources & Further Reading
- Google — Create and use Gems in Gemini — Official setup guide for Gemini Gems
- Cisco — ACL Configuration Examples — Reference for verifying ACL syntax the Gem generates
- RFC 4271 — BGP-4 — The authoritative reference for BGP behavior when you need to go deeper than the Gem
Do you use AI tools in your network engineering work? What tasks do you find them most useful for? Let me know in the comments.
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