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
CWDM uses fewer, wider channels. DWDM uses a tighter grid and more channels. The calculators name a wavelength or a grid slot from a number you type. They do not enable an optic. Two services on the same wavelength do not share a fiber politely.
One span you administer. Write the channel, the direction, and the optic. A documentation wavelength is an example until you match it to a part you own. Do not enable the optic during the reading.
The loss budget still has to close. This page only picks the channel.
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 span.
- Pick CWDM or DWDM.
- Write one channel.
- Confirm it is not already used.
- Do not enable an optic.
- Stop.
Mistakes that outlive the command
DWDM and CWDM Explained goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- Two services on one wavelength.
- An optic enabled during the reading.
- A grid slot you do not own.
- A span you do not administer.
- Loss forgotten.
Decisions to write down
One decision for DWDM and CWDM Explained: The span is yours. One unused channel is named. The family is CWDM or DWDM. Nothing was enabled. And the loss note is still required.
Checks before you call it done
Confirm this before you call the change done: The span is written. The channel is written. The direction is written. No optic was enabled. And no second service shares the wavelength. If one of those fails, stop.
Before you leave the device
DWDM and CWDM 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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