Network OS Administration Guide

Supporting Network OS 6.0.1a

Part Number: 53-1003768-04

Preconditions for zone merging

When a new switch is added to a VCS fabric, it automatically inherits the zone configuration information from the fabric. You can verify the zone configuration on any switch by using the procedure described in Viewing the defined configuration. Take care to avoid mismatched enabled-configuration scenarios.

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When edits are made to the defined configuration, and those edits affect a currently enabled zone configuration, issuing a "cfg-save" command makes the enabled configuration effectively stale. Until the enabled configuration is reenabled, the merging of new RBridges into the cluster is not recommended. This merging may cause unpredictable results, with the potential for mismatched enabled-zoning configurations among the RBridges in the cluster.

If you are adding a switch that is already configured for zoning, you must clear the zone configuration on that switch before connecting it to the zoned fabric. Refer to Clearing all zone configurations for instructions.

Adding a new fabric that has no zone configuration information to an existing zoned fabric is very similar to adding a new switch. All switches in the new fabric inherit the zone configuration data. If the existing fabric has an effective zone configuration, then the same configuration becomes the effective configuration for all switches in the added fabric.

To prevent an unwanted zone merge, use the no fabric isl enable command on ISL interfaces instead of the shutdown command on tengigabitethernet ports.

Before the new fabric can merge successfully, it must satisfy the following criteria:

  • Before merging
    • Ensure that all switches adhere to the default zone merge rules as described in Zone merging scenarios.
    • Ensure that the enabled and defined zone configurations match. If they do not match and you merge with another switch, the merge might be successful, but unpredictable zoning and routing behavior can occur. Refer to the Caution in this section and refer to Viewing the defined configuration.
  • Merging and segmentation

The system checks each port as it comes online to determine whether the ports should be segmented. E_Ports come online on power up, enabling a switch, or adding a new switch, and the system checks the zone database to detect if the two database that can be merged safely. Refer to Zone merging scenarios.

Observe the following rules when merging zones:

  • Merging rules
    • Local and adjacent configurations: If the local and adjacent zone database configurations are the same, they will remain unchanged after the merge.
    • Enabled configurations: If there is an enabled configuration between two switches, the enabled zone configurations must match.
    • Zone membership: If a zoning object has the same name in both the local and adjacent defined configurations, the content and order of the members are important.
    • Objects in adjacent configurations: If a zoning object appears in an adjacent defined configuration, but not in the local defined configuration, the zoning object is added to the local defined configuration. The modified zone database must fit in the nonvolatile memory area allotted for the zone database.
    • Local configuration modification: If a local defined configuration is modified because of a merge, the new zone database is propagated to the other switches within the merge request.
  • Merging two fabrics

For best practices, the default-zone access modes should match, although this is not a requirement. Refer to Zone merging scenarios.

If the two fabrics have conflicting zone configurations, they will not merge. If the two fabrics cannot join, the ISLs between the switches will segment.

The transaction state after the merge depends on which switch is elected as the principal RBridge. The newly elected principal RBridge retains the same transaction information it had before the merge. Transaction data is discarded from any switch that lost its principal status during the merge.

  • Merge conflicts

When a merge conflict is present, a merge does not take place and the ISLs will segment.

If the fabrics have different zone configuration data, the system attempts to merge the two sets of zone configuration data. If the zones cannot merge, the ISLs will be segmented.

  • A merge is not possible under any of the following conditions:
    • Configuration mismatch: Zoning is enabled in both fabrics and the zone configurations that are enabled are different in each fabric.
    • Zone Database Size: The zone database size exceeds the maximum limit of another switch.
If the zone members on two switches are not listed in the same order, the configuration is considered a mismatch, and the switches will segment from the fabric. For example: cfg1 = z1; z2 is different from cfg1 = z2; z1 , even though the members of the configuration are the same. If zone members on two switches have the same names defined in the configuration, make sure the zone members are listed in the same order.