Cisco Nexus 5000 Series NX-OS Software Configuration Guide

About Registering Name Server Proxies

All name server registration requests come from the same port whose parameter is registered or changed. If it does not, then the request is rejected.

This authorization enables WWNs to register specific parameters for another node.

Registering Name Server Proxies

To register the name server proxy, perform this task:

About Rejecting Duplicate pWWNs

You can prevent malicious or accidental log in using another device’s pWWN by enabling the reject-duplicate-pwwn option. If you disable this option, these pWWNs are allowed to log in to the fabric and replace the first device in the name server database.

Rejecting Duplicate pWWNs

To reject duplicate pWWNs, perform this task:

About Name Server Database Entries

The name server stores name entries for all hosts in the FCNS database. The name server permits an Nx port to register attributes during a PLOGI (to the name server) to obtain attributes of other hosts. These attributes are deregistered when the Nx port logs out either explicitly or implicitly.

In a multiswitch fabric configuration, the name server instances running on each switch shares information in a distributed database. One instance of the name server process runs on each switch.

Displaying Name Server Database Entries

The following example shows how to display the name server database for all VSANs:

The following example shows how to display the name server database and statistical information for a specified VSAN:

The following example shows how to display the name server database details for all VSANs:

The following example shows how to display the name server database statistics for all VSANs:

About RSCN Information

A switch RSCN (SW-RSCN) is sent to registered hosts and to all reachable switches in the fabric.

Note The switch sends an RSCN to notify registered nodes that a change has occurred. It is up to the nodes to query the name server again to obtain the new information. The details of the changed information are not delivered by the switch in the RSCN sent to the nodes.

Displaying RSCN Information

The following example shows how to display registered device information:

Note The SCR table is not configurable. It is populated when hosts send SCR frames with RSCN information. If hosts do not receive RSCN information, then the show rscn scr-table command will not return entries.

About the multi-pid Option

If the RSCN multi-pid option is enabled, then RSCNs generated to the registered Nx ports may contain more than one affected port IDs. In this case, zoning rules are applied before putting the multiple affected port IDs together in a single RSCN. By enabling this option, you can reduce the number of RSCNs. For example, you have two disks (D1, D2) and a host (H) connected to switch 1. Host H is registered to receive RSCNs. D1, D2 and H belong to the same zone. If disks D1 and D2 are online at the same time, one of the following actions applies:

• The multi-pid option is disabled on switch 1— Two RSCNs are generated to host H: one for the disk D1 and another for disk D2.
• The multi-pid option is enabled on switch 1—A single RSCN is generated to host H, and the RSCN payload lists the affected port IDs (in this case, both D1 and D2).

Note Some Nx ports may not support multi-pid RSCN payloads. If so, disable the RSCN multi-pid option.

Configuring the multi-pid Option

To configure the multi-pid option, perform this task:

Suppressing Domain Format SW-RSCNs

A domain format SW-RSCN is sent whenever the local switch name or the local switch management IP address changes. This SW-RSCN is sent to all other domains and switches over the ISLs. The remote switches can issue GMAL and GIELN commands to the switch that initiated the domain format SW-RSCN to determine what changed. Domain format SW-RSCNs can cause problems with some non-Cisco SAN switches. For additional information, see the Cisco MDS 9000 Family Switch-to-Switch Interoperability Configuration Guide, available at the following location:

http://www.cisco.com/en/US/docs/storage/san_switches/mds9000/interoperability/guide/intopgd.html

To suppress the transmission of these SW-RSCNs over an ISL, perform this task:

Note You cannot suppress transmission of port address or area address format RSCNs.

Clearing RSCN Statistics

You can clear the counters and later view the counters for a different set of events. For example, you can keep track of how many RSCNs or SW-RSCNs are generated on a particular event (such as ONLINE or OFFLINE events). You can use these statistics to monitor responses for each event in the VSAN.

The following example shows how to clear the RSCN statistics for the specified VSAN:

After clearing the RSCN statistics, you can view the cleared counters by entering the show rscn statistics command:

Configuring the RSCN Timer

RSCN maintains a per VSAN event list queue, where the RSCN events are queued as they are generated. When the first RSCN event is queued, a per VSAN timer starts. Upon time-out, all the events are dequeued and coalesced RSCNs are sent to registered users. The default timer values minimize the number of coalesced RSCNs sent to registered users. Some deployments require smaller event timer values to track changes in the fabric.

Note The RSCN timer value must be the same on all switches in the VSAN. See the “RSCN Timer Configuration Distribution” section.

Note Before performing a downgrade, make sure that you revert the RCSN timer value in your network to the default value. Failure to do so will disable the links across your VSANs and other devices.

To configure the RSCN timer, perform this task:

In this example the event time-out value is set to 300 milliseconds for VSAN 12.

Verifying the RSCN Timer Configuration

You verify the RSCN timer configuration using the show rscn event-tov vsan command. The following example shows how to clear the RSCN statistics for VSAN 10:

RSCN Timer Configuration Distribution

Because the timeout value for each switch is configured manually, a misconfiguration occurs when different switches time out at different times. This means different N-ports in a network can receive RSCNs at different times. Cisco Fabric Services (CFS) infrastructure alleviates this situation by automatically distributing the RSCN timer configuration information to all switches in a fabric. This also reduces the number of SW-RSCNs. For additional information, see Chapter1, “Using Cisco Fabric Services”

RSCN supports two modes, distributed and nondistributed. In distributed mode, RSCN uses CFS to distribute configuration to all switches in the fabric. In nondistributed mode, only the configuration commands on the local switch are affected.

Note All configuration commands are not distributed. Only the rscn event-tov tov vsan vsan command is distributed.

Note Only the RSCN timer configuration is distributed.

The RSCN timer is registered with CFS during initialization and switchover. For high availability, if the RSCN timer distribution crashes and restarts or a switchover occurs, it resumes normal functionality from the state prior to the crash or switchover.

This section includes the following topics:

• Enabling RSCN Timer Configuration Distribution
• Locking the Fabric
• Committing the RSCN Timer Configuration Changes
• Discarding the RSCN Timer Configuration Changes
• Clearing a Locked Session
• Displaying RSCN Configuration Distribution Information

Enabling RSCN Timer Configuration Distribution

To enable RSCN timer configuration distribution, perform this task:

Locking the Fabric

The first action that modifies the database creates the pending database and locks the feature in the VSAN. Once you lock the fabric, the following situations apply:

• No other user can make any configuration changes to this feature.
• A copy of the configuration database becomes the pending database along with the first active change.

Committing the RSCN Timer Configuration Changes

If you commit the changes made to the active database, the configuration is committed to all the switches in the fabric. On a successful commit, the configuration change is applied throughout the fabric and the lock is released.

To commit RSCN timer configuration changes, perform this task:

Discarding the RSCN Timer Configuration Changes

If you discard (abort) the changes made to the pending database, the configuration database remains unaffected and the lock is released.

To discard RSCN timer configuration changes, perform this task:

Clearing a Locked Session

If you have changed the RSCN timer configuration 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.

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

To use administrative privileges and release a locked DPVM session, use the clear rscn session vsan command in EXEC mode. The following example shows how to clear the RSCN session for VSAN 10:

Displaying RSCN Configuration Distribution Information

The following example shows how to display the registration status for RSCN configuration distribution:

Note A merge failure results when the RSCN timer values are different on the merging fabrics.

The following example shows how to display the set of configuration commands that would take effect when you commit the configuration:

Note The pending database includes both existing and modified configuration.

The following example shows how to display the difference between pending and active configurations: