Table Of Contents
Distributing Device Alias Services
About Device Aliases
Device Alias Features
Device Alias Requirements
Zone Aliases Versus Device Aliases
Device Alias Databases
About Device Alias Distribution
Device Alias Statistics Cleanup
Database Merge Guidelines
Default Settings
Distributing Device Alias Services
All switches in the Cisco MDS 9000 Family support Distributed Device Alias Services (device alias) on a per VSAN basis and on a fabric-wide basis. Device alias distribution allows you to move host bus adapters (HBAs) between VSANs without manually reentering alias names.
This chapter includes the following sections:
•
About Device Aliases
•Device Alias Databases
•Database Merge Guidelines
•Default Settings
About Device Aliases
When the port WWN of a device must be specified to configure different features (zoning, QoS, port security) in a Cisco MDS 9000 Family switch, you must assign the right device name each time you configure these features. An inaccurate device name may cause unexpected results. You can circumvent this problem if you define a user-friendly name for a port WWN and use this name in all the configuration commands as required. These user-friendly names are referred to as device aliases in this chapter.
This section includes the following topics:
•Device Alias Features
•Device Alias Requirements
•Zone Aliases Versus Device Aliases
Device Alias Features
Device aliases have the following features:
•The device alias information is independent of your VSAN configuration.
•The device alias configuration and distribution is independent of the zone server and the zone server database.
•You can import legacy zone alias configurations without loosing data.
•The device alias application uses the Cisco Fabric Services (CFS) infrastructure to enable efficient database management and distribution. Device aliases use the coordinated distribution mode and the fabric-wide distribution scope (see Chapter 5, "Using the CFS Infrastructure").
•When you configure zones, IVR zones, or QoS features using device aliases, and if you display these configurations, you see that the device aliases are displayed along with their respective pWWNs.
Device Alias Requirements
Device aliases have the following requirements:
•You can only assign device aliases to pWWNs.
•The mapping between the pWWN and the device alias to which it is mapped must have a one-to-one relationship. A pWWN can be mapped to only one device alias and vice versa.
•A device alias name is restricted to 64 alphanumeric characters and may include one or more of the following characters:
–a to z and A to Z
–1 to 9
–- (hyphen) and _ (underscore)
–$ (dollar sign) and ^ (up carat)
Zone Aliases Versus Device Aliases
Table 23-1 compares the configuration differences between zone-based alias configuration and device alias configuration.
Table 23-1 Comparison Between Zone Aliases and Device Aliases
Zone-Based Aliases
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Device Aliases
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Aliases are limited to the specified VSAN.
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You can define device aliases without specifying the VSAN number. You can also use the same definition in one or more VSANs without any restrictions.
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Zone aliases are part of the zoning configuration; the alias mapping cannot be used to configure other features.
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Device aliases can be used with any feature that uses the pWWN.
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You can use any zone member type to specify the end devices.
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Only pWWNs are supported along with new device aliases like IP addresses.
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Configuration is contained within the zone server database and is not available to other features.
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Device aliases are not restricted to zoning. Device alias configuration is available to the FCNS, zone, fcping, traceroute, and IVR applications.
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Device Alias Databases
The device alias feature uses two databases to accept and implement device alias configurations.
•Effective database—The database currently used by the fabric.
•Pending database—Your subsequent device alias configuration changes are stored in the pending database.
If you modify the device alias configuration, you need to commit or discard the changes as the fabric remains locked during this period.
This section includes the following topics:
•About Device Alias Distribution
About Device Alias Distribution
By default, device alias distribution is enabled. The device alias feature uses the coordinated distribution mechanism to distribute the modifications to all switches in a fabric.
If you have not committed the changes and you enable distribution, then a commit task will fail.
Device Alias Statistics Cleanup
To clear device alias statistics (for debugging purposes), refer to the Cisco MDS 9000 Family CLI Configuration Guide.
Database Merge Guidelines
Refer to the "CFS Merge Support" section on page 5-8 for detailed concepts.
When merging two device alias databases, follow these guidelines:
•Verify that two device aliases with different names are not mapped to the same pWWN.
•Verify that two different pWWNs are not mapped to the same device alias.
•Verify that the combined number of the device aliases in both databases does not exceed 8191 (8K). For example, if database N has 6000 device aliases and database M has 2192 device aliases, this merge operation will fail.
Default Settings
Table 23-2 lists the default settings for device alias parameters.
Table 23-2 Default Device Alias Parameters
Parameters
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Default
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Database in use
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Effective database.
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Database to accept changes
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Pending database.
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Device alias fabric lock state
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Locked with the first device alias task.
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