> # Configuring Port Blocking

> If you block a port, the port is retained in the operationally down state. If you unblock a port, a port initialization is attempted. When a port is blocked, data and control traffic are not allowed on that port.

> Physical Fibre Channel port blocks will continue to transmit an Off-line state (OLS) primitive sequence on a blocked port.

> Note The shutdown/no shutdown port state is independent of the block/no block port state.

> ## Restrictions

> You cannot block or prohibit the CUP port (0XFE). If a port is shut down, unblocking that port does not initialize the port.

> ## Detailed Steps

> To block or unblock port addresses in a VSAN using Device Manager, follow these steps:

> 1. Choose FICON > VSANs.
> 2. Select a VSAN ID and click Port Configuration.

> You see the FICON Port Configuration dialog box for the selected VSAN.

> 3. Check the Blocked check box for the port that you want to block.
> 4. Click Apply to save the changes.

> Copyright 2010-2015, Cisco Systems, Inc. All rights reserved.