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
Spanning tree blocks redundant links so a loop does not flood the VLAN. The root is the switch with the best priority. If you leave the default, an accidental switch can become root.
The calculators draft a priority or a cost from numbers you type. They do not log into a switch. A blocked port is a success when it is the port you named.
Turning the protocol off is how a loop wins. Edge ports for end devices are a feature you enable on purpose, not on an uplink.
This page does not redesign a campus. It records the root and one blocked port for one lab VLAN.
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 root switch.
- Write the priority you would set.
- Name the port that should block.
- Say which VLAN.
- Leave the protocol on.
- Do not change production priority from this page.
Mistakes that outlive the command
Spanning Tree Protocol (STP) Explained goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- Spanning tree disabled.
- Default priority left to chance.
- An edge setting on an uplink.
- Two roots because the ids differ and nobody looked.
Decisions to write down
One decision for Spanning Tree Protocol (STP) Explained: The root is named. The blocked port is named. The protocol stays on. Uplinks are not edge ports. And no production priority was changed.
Checks before you call it done
Confirm this before you call the change done: Root and port are in the ticket. The VLAN is named. Priority is a number or still a plan. The protocol is on. And a second person agrees which port blocks. If one of those fails, stop.
Name the root. Keep spanning tree on.
Do not disable it to light a link.Before you leave the device
Spanning Tree Protocol (STP) Explained 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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