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
Equal-cost multipath installs more than one next hop for the same prefix. A hash picks a path per flow. The calculator shows how a hash might pin. It does not change a router. One flow still uses one path, so a single transfer will not fill every link.
The paths have to be equal in the protocol's eyes, on a router you administer. Do not add a static route during the reading to force equality. Write the prefix and the next hops.
A polarization problem, if you have one, is a later change of the hash.
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 prefix.
- List the equal next hops.
- Read how a flow pins.
- Do not add a route.
- Do not change the hash yet.
- Stop.
Mistakes that outlive the command
ECMP Load Balancing Explained goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- Expecting one flow to fill every link.
- Unequal paths called equal.
- Adding routes during the reading.
- A router you do not administer.
Decisions to write down
One decision for ECMP Load Balancing Explained: The prefix is yours. The next hops are equal on paper. One flow is one path. Nothing was changed. And the hash change waits.
Checks before you call it done
Confirm this before you call the change done: The prefix is written. The next hops are written. The hash is named. No route was added. And no router was changed. If one of those fails, stop.
Before you leave the device
ECMP Load Balancing 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.
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.