You know the spreadsheet. It has 47 tabs, one for each VLAN. The formulas broke six months ago. Nobody's sure if it matches reality anymore. Here's why it fails and what actually works.

The IP Address Spreadsheet Problem

Almost every network team starts with Excel. It makes sense—you already have it, it's flexible, and the first version takes five minutes to create.

Then reality sets in:

Nobody updates it: The spreadsheet says 10.1.1.50 is available, but someone assigned it last week during a change window and forgot to update the doc
Version control nightmares: "IP_addresses_FINAL_v3_UPDATED_johns_version.xlsx" sitting in three different SharePoint folders
Collaboration breaks down: Two people edit different copies, changes get lost, conflicts appear
Scaling is painful: Managing a /16 means 65,000 potential rows. Excel starts choking around 50,000.
No validation: Nothing stops someone from entering "10.1.1.500" or duplicating an existing assignment

Why Teams Keep Using It Anyway

The alternatives haven't been great:

Enterprise IPAM tools: $35,000-300,000/year. Requires dedicated infrastructure, training, and ongoing maintenance. Overkill for most teams.
Open-source IPAM (phpIPAM, NetBox): Free but requires database setup, web servers, and network scanning infrastructure. Still too much overhead.
Cloud IPAM services: Monthly fees for features you might not need. Yet another login and integration to manage.

So teams stick with Excel because the alternatives require more effort than the problem seems to justify.

The Real Source of Truth

Here's the thing: your most accurate IP data already exists. It's in your firewall configuration.

Think about it. Your FortiGate or Palo Alto config contains:

Every address object you've defined
All subnets and their assignments
Interface IP addresses
VIP/NAT mappings
Static routes showing network topology

This data is always current because the firewall won't work if it's wrong. It's maintained as part of normal operations. It doesn't require a separate update process.

The spreadsheet is always trying to mirror what's in the firewall config anyway—so why not just read the config directly?

Config Parsing vs. Spreadsheets

Problem	Excel	Config Parsing
Data accuracy	Depends on manual updates	Always matches live config
Update process	Manual, often forgotten	Re-upload config anytime
Version conflicts	Common	Single source of truth
Setup time	Quick initially, grows complex	Instant results
Multi-site	Multiple files, chaos	Upload each config separately
Export capability	It's already a spreadsheet	Export to CSV

The Best of Both Worlds

You don't have to give up spreadsheets entirely. Here's a better workflow:

Export your firewall config (you should be doing this for backups anyway)
Parse the config to extract all IP data automatically
Export to CSV for analysis, documentation, or compliance reports
Keep the CSV as a snapshot rather than a living document

Need updated information? Just re-export the firewall config and parse again. Takes seconds, always accurate.

When You Actually Need Excel

Config parsing covers what's currently configured. Excel (or a proper IPAM tool) might still make sense for:

IP planning: Allocating space for future projects before they're configured
Reservation tracking: Recording IPs reserved but not yet assigned
Historical records: Tracking who requested what and when
DHCP ranges: Documenting dynamic pools that aren't in firewall config

For everything else—understanding what's actually deployed—let the config be your source of truth.

Try It Now

SimpleIPAM parses FortiGate and Palo Alto configs and shows you every IP address, subnet, interface, VIP, and route in seconds.

Upload Your Config

No signup. No infrastructure. Just drag, drop, and see your IP space organized.

Tagged: excel, spreadsheet, ipam, best-practices

Stop Managing IP Addresses in Excel: There's a Better Way