Cisco MDS: Zoning Merge failure, reason: Default zoning policy conflict

Adding a new switch to existing fabric with different "default-zone" setting

Creation of new Port-Channels fails to merge with existing Cisco Fabric.

New Switch
"show logging log" shows the following on the new switch being added to the fabric.

%ZONE-2-ZS_MERGE_FAILED: %$VSAN 802%$ Zone merge failure, isolating interface port-channel2 reason: Default zoning policy conflict.:[reason:0].
%PORT-5-IF_TRUNK_DOWN: %$VSAN 802%$ Interface port-channel2, vsan 802 is down (Isolation due to zone merge failure)

"show zone status" shows the following on the newer switch being added to the fabric:

VSAN: 802 default-zone: deny distribute: full Interop: default
mode: enhanced merge-control: allow
session: none
hard-zoning: enabled broadcast: unsupported
smart-zoning: disabled
rscn-format: fabric-address
activation overwrite control: disabled
Default zone:
qos: none broadcast: unsupported ronly: unsupported
Full Zoning Database :
DB size: 164 bytes
Zonesets:0 Zones:0 Aliases: 0 Attribute-groups: 1
Active Zoning Database :
Database Not Available
Current Total Zone DB Usage: 164 / 4000000 bytes (0 % used)
Pending (Session) DB size:
Full DB Copy size: 0 bytes
Active DB Copy size: 0 bytes
SFC size: 0 / 4000000 bytes (0 % used)
Status:

Existing Switch
"show logging log" shows the following on the existing switch already part of the fabric:

%ZONE-2-ZS_MERGE_FAILED: %$VSAN 802%$ Zone merge failure, isolating interface port-channel9 reason: Default zoning policy conflict.:[reason:0]
%PORT-5-IF_TRUNK_DOWN: %$VSAN 802%$ Interface port-channel9, vsan 802 is down (Isolation due to zone merge failure)

"show zone status" shows the following on the existing switch already part of the fabric:

Zone Status
VSAN: 802 default-zone: permit distribute: full Interop: default
mode: enhanced merge-control: allow
session: none
hard-zoning: enabled broadcast: unsupported
smart-zoning: disabled
rscn-format: fabric-address
activation overwrite control: disabled
Default zone:
qos: none broadcast: unsupported ronly: unsupported
Full Zoning Database :
DB size: 812112 bytes
Zonesets:2 Zones:6337 Aliases: 551 Attribute-groups: 1
Active Zoning Database :
DB size: 409224 bytes
Name: Virtualization_EVEN Zonesets:1 Zones:5920
Current Total Zone DB Usage: 1221336 / 4000000 bytes (30 % used)
Pending (Session) DB size:
Full DB Copy size: 0 bytes
Active DB Copy size: 0 bytes
SFC size: 0 / 4000000 bytes (0 % used)
Status: Activation completed at 12:55:25 UTC Jun 20 2019

As per the above symptoms the newer switch was configured for with "default-zone: deny", and the existing switch is already part of the customers fabric with "default-zone: permit."
This conflict would not allow the newer switch merge zoning with the existing causing rejects to be sent by both switches.

Resolution
Issue the following on the "Existing" switch.

Step 1:
VSAN 802 is Isolated as follows:

VSAN 802%$ Zone merge failure, isolating interface port-channel9 reason: Default zoning policy conflict.:[reason:0]

The default zoning policy is different on each switch:
Switch New

VSAN: 802 default-zone: deny

Switch Existing:

VSAN: 802 default-zone: perit

Perform the following actions on Switch Existing.
Example as follows from the lab switch:

MDS9513#conf t
Enter configuration commands, one per line. End with CNTL/Z.
MDS9513(config)# no zone default-zone permit vsan 802
MDS9513(config)# end
MDS9513#copy run start

Step 2: Display the zoning status with the show zone status command.

MDS9513# sh zone status vsan 802
VSAN: 802 default-zone: deny

If any of the above is unclear or the fix does not correct the issue, then escalate to Dell Support Center.

Refer to this video: