Documenting Your Own Network

A well-built network runs for years untouched. That's good news, and precisely the problem: when something finally needs changing, nobody remembers how it was put together.

The questions are always the same. Where does this cable go. Why does the printer have a pinned address. What's the router admin password. What's that thing humming in the rack. And most often: what changed last, because today's fault is probably its consequence.

What to record

One page is enough, and one page is better, because a long document never gets updated.

Service and subscription. Provider name, account number, plan and speed, installation date, and the installation ticket number. That's what they ask for first every time you call.

Equipment. For each: make and model, where it sits, and the year it was bought. The model tells you later whether it still gets updates (updating router firmware), and the purchase year answers the question raised in when to replace a router.

Settings addresses. The admin page address for the router and other devices, written literally. Note the address range the router hands out too, since that's what you use when adding devices (local IPs and DHCP).

Devices with fixed addresses. A short list of printers, cameras, network storage, and tills with the address pinned to each. This is the most-searched-for and least-recorded part.

Networks broadcast. Each network name and what it's for: main, guest, smart devices. If there's separation, say what separates them (separating a guest network).

Cable routes. No diagram needed. Photos, plus a sentence like "cable from router to front bedroom through the corridor ceiling". Photos are far more useful than drawings, and far more likely to actually get made.

A change log. One line per change, dated. This is the part that saves the most time, because faults almost always begin with one change nobody considered important.

What must never be in it

Passwords. Network notes tend to travel: sent to a technician, left on a desk, copied to a colleague. Passwords mustn't travel with them. Keep them in a password manager, and in the notes record only where they live.

The two most important to keep out: the router admin password (default ISP router admin accounts) and camera passwords, because both grant far more access than they appear to.

Physical labels, the biggest time saver

The highest return for the effort involved. A few cheap labels remove all the guessing:

• Both ends of every LAN cable labelled with their destination. Unlabelled cable in a rack turns every small change into half an hour's work.
• Power adapters labelled with their device. Adapters all look alike, their voltages aren't necessarily the same, and unplugging the wrong one mid-shift is an easily avoided mistake. Replacements are covered in failed router adapters.
• Switches and ports that must not be unplugged marked, especially in busy premises.

Once there's enough equipment to need a rack, the arrangements are in choosing a network rack.

Where to keep it

Two copies, for a practical reason: a network fault means you can't open a document stored online.

• One copy online, so it can be opened from anywhere and doesn't vanish with a device.
• One copy printed or on a phone, near the equipment. That's the one actually used when the internet is down, which is exactly when it's needed.

For a business, also keep it somewhere more than one person can open. Documentation that exists only on the owner's laptop is the same as none when the owner isn't around.

When to update it

Not on a schedule, because scheduled reviews don't happen. Update at the moment of change, and the list is short: adding or replacing equipment, changing a fixed address, changing plan or provider, and adding a network.

One line at the time, dated. That alone separates notes that help from notes that are now wrong, which are worse than having none.

For a business, two additions

If this network runs a business, two things deserve a place and are usually forgotten:

• Who to call and in what order: internet provider, the installer, the building owner. With numbers and service hours. This is what's hunted for when whoever usually handles it isn't available.
• What holds personal data. Camera recordings, customer records, guest Wi-Fi logs, and how long each is kept. This isn't mere tidiness, since the duty to protect and limit retention is covered in personal data security and the PDP law and, for those offering Wi-Fi to customers, in log retention duties for Wi-Fi providers.

Frequently asked questions