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
An autonomous system number identifies a routing domain in BGP. The lookup and the prefix list show what a public source says about a number or an address you type. They do not open a session.
A prefix list is not permission to originate those prefixes. You announce only what you were assigned. Someone else's ASN is a label, not a network you may borrow and not an identity.
One number or one address. 192.0.2.0/24 will not be a real origin. Write the source of the answer and the time. Public data changes.
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.
- Type one ASN or one address you may look up.
- Read the label.
- Write that you will not originate a foreign prefix.
- Do not open a BGP session.
- Do not treat the number as a person.
- Stop.
Mistakes that outlive the command
What Is an ASN? goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- Originating a prefix because it appeared in the list.
- A new BGP session to test the lookup.
- Calling the ASN a person.
- A bulk list you have no reason to hold.
Decisions to write down
One decision for What Is an ASN?: One number was read. No prefix was originated. No session was opened. The label is not an identity. And the time is written.
Checks before you call it done
Confirm this before you call the change done: The ASN or address is written. The label is written. Foreign prefixes stay foreign. No session was configured. And a second person can see the scope. If one of those fails, stop.
Before you leave the device
What Is an ASN? 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.
Tools for this guide
These tools run in the browser on this site. They do not log into your machines.
Related pillar guides
More in this cluster
The pillar for this page, and the next published pages filed with it.