Enhanced Zone merge in MDS9396T

[manoj-singh]

I am migrating from 9396S to 9396T through ISL based migration, 9396S (OLD SWITCH) has Enhanced zone set with valid zones,
Question is, I shall set Enhanced zone on 9396T, but the warning below is confusing, if I continue, doesn't the empty zoneset get pushed to the old switch (9396S)

zone mode enhanced vsan 103
WARNING: This command would distribute the zoning database of this switch throughout the fabric. Do you want to continue? (y/n) [n] ^C

[Jason Mooney · Accepted solution]

Hi Manoj-Singh,

Great question — and that warning can definitely be misleading if you're doing this for the first time.

What the warning actually means:

When you run:

zone mode enhanced vsan 103

...the switch prepares to enable enhanced zoning and distribute its own zoning database to the fabric only if:

• An ISL is already up
• A zone merge is attempted and successful

But since your 9396T switch has an empty zoning database, and you're just preparing it before the ISL is connected — no merge occurs at that moment.

What you should do:

1. Configure zone mode enhanced vsan 103 on the new switch before connecting the ISL.
2. Ignore the warning — just type y and continue.
3. Connect the ISL — the existing zoning database from the old switch (9396S) will be retained and propagated to the new switch (9396T), not the other way around.
4. Verify merge using show zone status and show logging logfile.
5. Optional: If it doesn’t merge, you can manually import zones with:
   zoneset import interface fcX/Y vsan 103

Summary:

Behavior	Reality
Warning message says zoning DB will be distributed	Only happens if ISL is up and merge is successful
9396T is empty, 9396S has valid zoning	9396S’s zoneset will win if merge occurs
You’re safe to enable Enhanced Zoning now	Yes — just make sure VSAN and zoning modes match

These are my personal responses and do not represent official guidance by Cisco Systems, Inc.