This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.
What this hour is for
Containerlab and the topology generator draft a lab file. The lab runs on a machine you administer. It does not connect to a production VLAN and it does not advertise a prefix to the internet.
One small topology: two routers, or a router and a switch, for the protocol you are reading about. Images you pull are from a source you trust. A lab that bridges to the office LAN will answer ARP and DHCP you did not mean to answer.
Secrets in a lab config are still secrets if the file is shared. Use prompt-for-this. Tear the lab down when the note is written.
Do not point the lab at a network you do not administer.
The change you can finish
Apply nothing during the writing of the note. When the lab window opens, it is one change on the device named in the ticket. Read the draft, then the device, then decide.
Rollback is the file or the revision you saved first. You do not invent a rollback after the only copy is gone.
- Name the protocol the lab is for.
- Draft a two-node topology.
- Keep it bridged only to itself.
- Use prompt-for-this for any secret.
- Do not advertise a lab prefix.
- Tear it down when the note is done.
Mistakes that outlive the command
Building Network Labs with Containerlab goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- A bridge onto the office LAN.
- A lab prefix advertised upstream.
- An image from a source you cannot name.
- A secret in the topology file.
- A production device added as a node.
Decisions to write down
One decision for Building Network Labs with Containerlab: The lab is isolated. The topology matches the note. No prefix was advertised. Secrets are placeholders. And production is not a node.
Checks before you call it done
Confirm this before you call the change done: The topology is named. The bridge is the lab only. No upstream advertisement exists. The file has no live secret. And the lab has an end time. If one of those fails, stop.
Before you leave the device
Building Network Labs with Containerlab ends when the hostname on the device matches the hostname in the ticket. If it does not, you are on the wrong box. Stop. A command that succeeded on the wrong box is not progress.
The draft stays a draft until a person has read the names in it. A generator does not log into the device and does not know which interface is the uplink. You delete a line that names a device, a zone, or a prefix you did not write down.
0.0.0.0/0 is not kept because a sample included it. A source you can say is the source you keep. 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. They belong in the note. They are not prefixes you type onto a production device because they appeared in a draft.
prompt-for-this is a reminder that a secret is missing. It is not a password, a key, a community string, or a pre-shared key you save in the ticket or in git. The real secret stays in the store.
One change is the window. A VLAN and a routing protocol and a VPN do not share it. If two things move and the result is wrong, you will not know which one did it. The next feature waits for its own page.
If the same step fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied config produces a device nobody can rebuild. Restore the copy you took first.
A second person reads the device name and the change aloud. If they cannot find them in the ticket, the note is not done. Silence is not agreement. Then leave the device alone.
This page is a planning guide. It is not a vendor manual, not an official standard, and not a permission to touch a network you do not administer. The pillar guide owns the wider design. This page owns one lab proof.
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