Table Of Contents

Distributing Device Alias Services

About Device Aliases

Device Alias Features

Device Alias Requirements

Zone Aliases Versus Device Aliases

Modifying the Device Alias Database

Locking The Fabric

Committing Changes

Discarding Changes

Fabric Lock Override

Device Alias Distribution

Legacy Zone Alias Configuration Conversion

Database Merge Guidelines

Device Alias Statistics Cleanup

Device Alias Configuration Verification

Default Settings

Distributing Device Alias Services

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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.

This chapter includes the following sections:

•About Device Aliases

•Device Alias Features

•Device Alias Requirements

•Zone Aliases Versus Device Aliases

•Modifying the Device Alias Database

•Fabric Lock Override

•Device Alias Distribution

•Legacy Zone Alias Configuration Conversion

•"Database Merge Guidelines" section

•Device Alias Statistics Cleanup

•Device Alias Configuration Verification

•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.

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.

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 configuration, you will automatically 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.

•Ensure that the mapping between the pwwn and the device alias to which it is mapped has 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)

–$ and ^

Zone Aliases Versus Device Aliases

Table 20-1 compares the configuration differences between zone-based alias configuration and device alias configuration.

Table 20-1 Comparison Between Zone Aliases and Device Aliases 

Zone-Based Aliases	Device Aliases
Aliases are limited to the specified VSAN	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.
Zone aliases are part of the zoning configuration, the alias mapping cannot be used to configure other features.	Device aliases can be used to any feature that uses the pWWN.
You can use any zone member type to specify the end devices.	Only pWWNs are supported along with new device aliases like IP addresses.
Configuration is contained within the Zone Server database and is not available to other features.	Device aliases are not restricted to zoning. Device alias configuration is available to the FCNS, zone, fcping, traceroute, and IVR applications.

Modifying the Device Alias Database

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.

Locking The Fabric

When you perform the first device alias task (regardless of which device alias task), the fabric is automatically locked for the device alias feature. Once you lock the fabric, the following situations apply:

•No other user can make any configuration changes to this feature.

•A copy of the effective database is obtained and used as the pending database. Modifications from this point on are made to the pending database. The pending database remains in effect until you commit the modifications to the pending database or discard (abort) the changes to the pending database.

To lock the fabric and modify the device alias configuration in the pending database, follow these steps:

	Command	Purpose
Step 1	switch# config t switch(config)#	Enters configuration mode.
Step 2	switch(config)# device-alias database switch(config-device-alias-db)#	Enters the pending database configuration submode.
Step 3	switch(config-device-alias-db)# device-alias name x pwwn 21:01:00:e0:8b:2e:80:93	Specifies a device name (x) for the device that is identified by its pWWN. Starts writing to the pending database and simultaneously locks the fabric as this is the first-issued device alias configuration command.
	switch(config-device-alias-db)# no device-alias name Doc	Removes the device name (SampleName) for the device that is identified by its pWWN.

Committing Changes

If you commit the changes made to the pending database, the following events occur:

1. The pending database contents overwrites the effective database contents.

2. The pending database is emptied of its contents.

3. The fabric lock is released for this feature.

To commit the changes, follow these steps:

	Command	Purpose
Step 1	switch# config t switch(config)#	Enters configuration mode.
Step 2	switch(config)# device-alias commit	Commits the changes made to the currently active session.

Discarding Changes

If you discard the changes made to the pending database, the following events occur:

1. The effective database contents remain unaffected.

2. The pending database is emptied of its contents.

3. The fabric lock is released for this feature.

To discard the device alias session, follow these steps:

	Command	Purpose
Step 1	switch# config t switch(config)#	Enters configuration mode.
Step 2	switch(config)# device-alias abort	Discards the currently active session.

Fabric Lock Override

If you have performed a device alias task and have forgotten to release the lock by either committing or discarding the changes, an administrator can release the lock from any switch in the fabric. If the administrator performs this task, your changes to the pending database are discarded and the fabric lock is released.

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Tip The changes are only available in the volatile directory and are subject to being discarded if the switch is restarted.

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To use administrative privileges and release a locked device alias session, use the clear device-name session command in EXEC mode.

switch#  clear device-alias session 

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 (see Example 20-10).

To enable the device alias distribution, follow these steps:

	Command	Purpose
Step 1	switch# config t switch(config)#	Enters configuration mode.
Step 2	switch(config)# device-alias distribute	Enables the distribution (default).
	switch(config)# no device-alias distribute	Disables the distribution.

Legacy Zone Alias Configuration Conversion

You can import legacy zone alias configurations to use this feature without loosing data, if they satisfy the following restrictions:

•Each zone alias has only one member.

•The member type is pWWN.

•The name and definition of the zone alias should not be the same as any existing device alias name.

If any name conflict exists, the zone aliases are not imported.

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Tip Ensure to copy any required zone aliases to the device alias database as required by your configuration.

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When an import operation is complete, the modified alias database is distributed to all other switches in the physical fabric when you perform the commit operation. At this time if you do not want to distribute the configuration to other switches in the fabric, you can perform the abort operation and the merge changes are completely discarded.

To import the zone alias for a specific VSAN, follow these steps:

	Command	Purpose
Step 1	switch# config t switch(config)#	Enters configuration mode.
Step 2	switch(config)# device-alias import fcalias vsan 3	Imports the fcalias information for the specified VSAN.

Database Merge Guidelines

Refer to the "CFS Merge Support" section on page 5-7 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 identical pWWNs are not mapped to two different device aliases.

•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.

Device Alias Statistics Cleanup

Use the clear device-name statistics command to clear device alias statistics (for debugging purposes):

switch# clear device-alias statistics

Device Alias Configuration Verification

You can view device alias information by using the show device-alias command. See Examples 20-1 to 20-20.

Example 20-1 Displays All Configured Device Aliases from the Effective Database

switch# show device-alias database

device-alias name SampleName pwwn 21:00:00:e0:8b:0b:66:56

device-alias name x pwwn 21:01:00:e0:8b:2e:80:93

Total number of entries = 2

Example 20-2 Displays the Specified Device Name

switch# show device-alias name x

device-alias name x pwwn 21:01:00:e0:8b:2e:80:93

Example 20-3 Displays the Pending Database with No Modifications

switch# show device-alias database pending

There are no pending changes

Example 20-4 Displays the Pending Database with Modifications

switch# show device-alias database pending

device-alias name x pwwn 21:01:00:e0:8b:2e:80:93

device-alias name SampleName pwwn 21:00:00:e0:8b:0b:66:56

device-alias name y pwwn 21:00:00:20:37:39:ab:5f

device-alias name z pwwn 21:00:00:20:37:39:ac:0d

Total number of entries = 4

Example 20-5 Displays the Specified Device Name in the Pending Database

switch# show device-alias name x pending

device-alias name x pwwn 21:01:00:e0:8b:2e:80:93

Example 20-6 Displays the Specified pWWN in the Pending Database

switch# show device-alias pwwn 21:01:00:e0:8b:2e:80:93 pending

device-alias name x pwwn 21:01:00:e0:8b:2e:80:93

Example 20-7 Displays the Difference between the Pending and Effective Databases

switch# show device-alias database pending-diff

- device-alias name Doc pwwn 21:01:02:03:00:01:01:01

+ device-alias name SampleName pwwn 21:00:00:e0:8b:0b:66:56

Example 20-8 Displays the Specified pWWN

switch# show device-alias pwwn 21:01:01:01:01:11:01:01 

device-alias name Doc pwwn 21:01:01:01:01:11:01:01

Example 20-9 Displays a Successful Device Alias Status

switch# show device-alias status

Fabric Distribution: Enabled <-------------------------------Distribution is enabled

Database:-Device Aliases 24

Locked By:-User "Test" SWWN 20:00:00:0c:cf:f4:02:83<-Lock holder's user name and switch ID

Pending Database:- Device Aliases 24

Status of the last CFS operation issued from this switch:

==========================================================

Operation: Enable Fabric Distribution

Status: Success

Example 20-10 Displays a Failed Device Alias Status

switch# show device-alias status

Fabric Distribution: Disabled

Database:- Device Aliases 25

Status of the last CFS operation issued from this switch:

==========================================================

Operation: Commit

Status: Failed (Reason: Operation is not permitted as the fabric distribution is

 currently disabled.)

Example 20-11 Displays the Device Alias Status of a abort Command

switch# show device-alias status

Fabric Distribution: Enabled

Database:- Device Aliases 24

Status of the last CFS operation issued from this switch:

==========================================================

Operation: Abort

Status: Success

Example 20-12 Displays the Device Alias Status of a Cleared Session

switch# show device-alias status

Fabric Distribution: Enabled

Database:- Device Aliases 24

Status of the last CFS operation issued from this switch:

==========================================================

Operation: Clear Session <--------------------Lock released by administrator

Status: Success <---------------------------------Successful status of the operation

Example 20-13 Displays the Device Alias Status When Distribution Is Disabled

switch# show device-alias status

Fabric Distribution: Disabled

Database:- Device Aliases 24

Status of the last CFS operation issued from this switch:

==========================================================

Operation: Disable Fabric Distribution

Status: Success

Example 20-14 Displays the Device Alias in the FLOGI Database

switch# show flogi database

---------------------------------------------------------------------------

INTERFACE  VSAN    FCID            PORT NAME               NODE NAME

---------------------------------------------------------------------------

fc2/9      1     0x670100  21:01:00:e0:8b:2e:80:93  20:01:00:e0:8b:2e:80:93

                           [x] <---------------------------------------------Device alias name

fc2/12     1     0x670200  21:00:00:e0:8b:0b:66:56  20:00:00:e0:8b:0b:66:56

                           [SampleName] <---------------------------------Device alias name

Total number of flogi = 2

Example 20-15 Displays the Device Alias in the FCNS Database

switch# show fcns database

VSAN 1:

--------------------------------------------------------------------------

FCID        TYPE  PWWN                    (VENDOR)        FC4-TYPE:FEATURE

--------------------------------------------------------------------------

0x670100    N     21:01:00:e0:8b:2e:80:93 (Qlogic)        scsi-fcp:init

                  [x]

0x670200    N     21:00:00:e0:8b:0b:66:56 (Qlogic)        scsi-fcp:init

                  [SampleName]

Total number of entries = 2

Example 20-16 Displays the fcping Statistics for the Specified Device Alias

switch# fcping device-alias x vsan 1

28 bytes from 21:01:00:e0:8b:2e:80:93 time = 358 usec

28 bytes from 21:01:00:e0:8b:2e:80:93 time = 226 usec

28 bytes from 21:01:00:e0:8b:2e:80:93 time = 372 usec

Example 20-17 Displays the fctrace Information for the Specified Device Alias

switch# fctrace device-alias x vsan 1

Route present for : 21:01:00:e0:8b:2e:80:93

20:00:00:05:30:00:4a:e2(0xfffc67)

Where available, device aliases are displayed regardless of a member being configured using a device-alias command or a zone-specific member pwwn command (see Example 20-18 and Example 20-19).

Example 20-18 Displays the Device Aliases in the Zone Set Information

switch# show zoneset

zoneset name s1 vsan 1

  zone name z1 vsan 1

    pwwn 21:01:00:e0:8b:2e:80:93 [x] <---------------Device alias displayed for each pWWN.

    pwwn 21:00:00:20:37:39:ab:5f [y]

  zone name z2 vsan 1

    pwwn 21:00:00:e0:8b:0b:66:56 [SampleName]

    pwwn 21:00:00:20:37:39:ac:0d [z]

Example 20-19 Displays the the Device Aliases in the Active Zone Set

switch# show zoneset active

zoneset name s1 vsan 1

  zone name z1 vsan 1

  * fcid 0x670100 [pwwn 21:01:00:e0:8b:2e:80:93] [x]

    pwwn 21:00:00:20:37:39:ab:5f [y]

  zone name z2 vsan 1

  * fcid 0x670200 [pwwn 21:00:00:e0:8b:0b:66:56] [SampleName]

    pwwn 21:00:00:20:37:39:ac:0d [z]

Example 20-20 Displays Statistics for the Device Alias Application

switch# show device-alias statistics

        Device Alias Statistics

===========================================

Lock requests sent: 2

Database update requests sent: 1

Unlock requests sent: 1

Lock requests received: 1

Database update requests received: 1

Unlock requests received: 1

Lock rejects sent: 0

Database update rejects sent: 0

Unlock rejects sent: 0

Lock rejects received: 0

Database update rejects received: 0

Unlock rejects received: 0

Merge requests received: 0

Merge request rejects sent: 0

Merge responses received: 2

Merge response rejects sent: 0

Activation requests received: 0

Activation request rejects sent: 0

Activation requests sent: 2

Activation request rejects received: 0

Default Settings

Table 20-2 lists the default settings for device alias parameters.

Table 20-2 Default Device Alias Parameters 

Parameters	Default
Database in use	Effective database.
Database to accept changes	Pending database.
Device alias fabric lock state	Locked with the first device alias task.