All switches in the Cisco MDS 9000 Series Switches provide port security features that reject intrusion attempts and report these intrusions to the administrator. Typically, any Fibre Channel device in a SAN can attach to any SAN switch port and access SAN services based on zone membership. Port security features prevent unauthorized access to a switch port in the following ways:

 Login requests from unauthorized Fibre Channel devices (Nx ports) and switches (xE ports) are rejected.

All intrusion attempts are reported to the SAN administrator through system messages.

Configuration distribution uses the CFS infrastructure and is limited to those switches that are CFS capable. Distribution is disabled by default.

Configuring the port security policy requires the ENTERPRISE_PKG license.

To enforce port security, configure the devices and switch port interfaces through which each device or switch is connected, and activate the configuration.

Use the port World Wide Name (pWWN) or the node World Wide Name (nWWN) to specify the Nx port connection for each device.

Use the switch World Wide Name (sWWN) to specify the xE port connection for each switch.

Each Nx and xE port can be configured to restrict a single port or a range of ports. Port security policies are enforced on every activation and when the port tries to come up. The port security feature uses two databases to accept and implement configuration changes:

 Configuration database: All configuration changes are stored in the configuration database.

 Active database: This database is currently enforced by the fabric. The port security feature requires all devices connecting to a switch to be part of the port security active database. The software uses this active database to enforce authorization.

You can instruct the switch to automatically learn (auto-learn) the port security configurations over a specified period. This feature allows any switch in the Cisco MDS 9000 Series Switches to automatically learn about devices and switches that connect to it. Use this feature when you activate the port security feature for the first time because it saves tedious manual configuration for each port. You must configure auto-learning on a per-VSAN basis. If enabled, devices and switches that are allowed to connect to the switch are automatically learned, even if you have not configured any port access.

When auto-learning is enabled, learning happens for the devices or interfaces that were already logged in to the switch and the new devices or interfaces that need to be logged in in the future. Learned entries on a port are cleaned up after you shut down that port if auto-learning is still enabled.

Learning does not override the existing configured port security policies. So, for example, if an interface is configured to allow a specific pWWN, auto-learning will not add a new entry to allow any other pWWN on that interface. All other pWWNs will be blocked even in auto-learning mode. No entries are learned for a port in the shutdown state. When you activate the port security feature, auto-learning is also automatically enabled. You cannot reactivate port security until auto-learning is disabled or deactivated and activated again.