Device Alias Modes; Changing Device Alias Mode Guidelines - Cisco Nexus 5000 Series Configuration Manual

Device Alias Databases
Example of Creating a Device Alias
To display the device alias configuration, use the show device-alias name command:
switch# show device-alias name x
device-alias name x pwwn 21:01:00:e0:8b:2e:80:93

Device Alias Modes

You can specify that aliases operate in basic or enhanced modes.
When operating in basic mode, which is the default mode, the device alias is immediately expanded to a
pWWN. In basic mode, when device aliases are changed to point to a new HBA, for example, that change is
not reflected in the zone server. Users must remove the previous HBA's pWWN, add the new HBA's pWWN,
and then reactivate the zoneset.
When operating in enhanced mode, applications accept a device alias name in its "native" format. Instead of
expanding the device alias to a pWWN, the device alias name is stored in the configuration and distributed
in its native device alias format. So applications such as zone server, PSM or DPVM can automatically keep
track of the device alias membership changes and enforce them accordingly. The primary benefit of operating
in enhanced mode is that you have a single point of change.
Whenever you change device alias modes, the change is distributed to other switches in the network only if
device alias distribution is enabled or on. Otherwise, the mode change only takes place on the local switch.
Note Enhanced mode, or native device alias-based configurations are not accepted in interop mode VSANs.
IVR zoneset activation will fail in interop mode VSANs if the corresponding zones have native device
alias-based members.

Changing Device Alias Mode Guidelines

When changing device alias modes, follow these guidelines:
• If two fabrics running in different device alias modes are joined together, the device alias merge will
fail. There is no automatic conversion to one mode or the other during the merge process. In this situation,
you must to select one mode over the other.
• Before changing from enhanced to basic mode, you must first explicitly remove all native device
alias-based configurations from both local and remote switches, or, replace all device alias-based
configuration members with the corresponding pWWN.
• If you remove a device alias from the device alias database, all applications will automatically stop
enforcing the corresponding device alias. If that corresponding device alias is part of an active zoneset,
all the traffic to and from that pWWN is disrupted.
• Renaming the device alias not only changes the device alias name in the device alias database, but also
replaces the corresponding device alias configuration in all the applications.
• When a new device alias is added to the device alias database, and the application configuration is present
on that device alias, it automatically takes effect. For example, if the corresponding device alias is part
of the active zoneset and the device is online, then zoning is enforced automatically. You do not have
to reactivate the zoneset.
Cisco Nexus 5000 Series NX-OS SAN Switching Configuration Guide
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Distributing Device Alias Services
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