What is the Behavior?
This KB is focused on an scenario in which the user is experiencing a ISL showing segmented - incompatible status
caused by a "ESC mismatch, VCS Virtual Fabric Mode Conflict"
What is a ISL?
- A inter switch link is used to connect VDX devices working as part of the same VCS Fabric, andrunningthe Network Operating System (NOS)
- These ISL linksare self-formed as long as the devices are correctly configure to be part of the same VCS Fabric
Why does ISL Segmentation occur?
Some of the reasons that can cause ISL segmentation are:
- VDX device experiencing a R-bridge ID conflict (every device in the fabric must have a unique RB id)
- A device working in a different VCS Fabric Mode (all devices need to work in the same VCS Mode)
- Configuration Mismatch (devices configuration needs to synchronize, if it is segmented for this reason, set the device in default configuration)
How can I check the status of an ISL?
The most useful commands for checkingthe status of ISLsare:
sw0# show fabric islports
Index Interface State Operational State
64 Te 2/0/1 Up ISL (Trunk port, Primary is 2/0/2 )
65 Te 2/0/2 Up ISL segmented,(ESC mismatch, VCS Virtual Fabric Mode Conflict)(Trunk Primary)
66 Te 2/0/3 Up ISL segmented,(ESC mismatch, VCS Virtual Fabric Mode Conflict)(Trunk Primary)
67 Te 2/0/4 Up ISL (Trunk port, Primary is 2/0/3 )
68 Te 2/0/5 Up ISL segmented,(ESC mismatch, VCS Virtual Fabric Mode Conflict)(Trunk Primary)
69 Te 2/0/6 Up ISL (Trunk port, Primary is 2/0/5 )
sw0# show fabric isl
Rbridge-id: 2 #ISLs: 3
Src Src Nbr Nbr
Index Interface Index Interface Nbr-WWN BW T runk Nbr-Name
65 Te 2/0/2 65 Te ?/?/? 10:00:50:EB:1A:13:F0:23 (segmented - incompatible)
66 Te 2/0/3 64 Te ?/?/? 10:00:50:EB:1A:E5:17:B4 (segmented - incompatible)
68 Te 2/0/5 68 Te ?/?/? 10:00:50:EB:1A:E5:1A:44 (segmented - incompatible)
How can this be fixed?
- First check the devices are actually working in the same VCS Mode; the show vcs command tells which vcs mode they are in
- In this particular scenario, both VDXs are showing Logical Chassis as their VCS Mode, and the ISL is still segmented
- After NOS version 5.0.0, Brocade supports virtual fabric mode; this will change the behavior of the switch, but it will not change the VCS Configuration, nor the VCS Mode displayed
- If the device has Virtual Fabric enabled, it will not be able to form a fabric with other devices unless they also have it
- Use the command show virtual-fabric status to confirm if the device has virtual fabric mode as enable, or if it is only capable (Disabled)
- Another way to verify this is in the device configuration show running-configrbridge id #
vcs virtual-fabric enable
zoning enabled-configuration cfg-name ""
- This issue can be fixed by disabling virtual-fabric modeon the device no vcs virtual-fabric enable
- Another way to resolve this is by setting the device to default configuration, letting it join the fabric and obtaining its configuration from other fabric members