user manual

Chapter 6 Managing Ports 185
4. Click the OK button to write the new port type to the switch.
I/O Stream Guard
The I/O Stream Guard feature suppresses the Registered State Change Notification
(RSCN) messages on a port basis. I/O Stream Guard should be enabled only on
ports connected to initiator devices. To configure the I/O Stream Guard option
using the Port Properties dialog, open the Port menu, and select Port Properties.
Select the option that corresponds to one of the following options:
■ Enable — suppresses the reception of RSCN messages from other ports for
which I/O Stream Guard is enabled.
■ Disable — allows free transmission and reception of RSCN messages.
■ Auto — suppresses the reception of RSCN messages when the port is
connected to an initiator device with a QLogic
®
HBA. The default is Auto.
Device Scan
The Device Scan feature queries the connected device during login for FC-4
descriptor information. Disable this parameter only if the scan creates a conflict with
the connected device.
Auto Performance Tuning and AL Fairness
The Auto Perf Tuning and AL Fairness settings are configured using the Advanced
Port Properties dialog (FIGURE 6-7). The Auto Perf Tuning option enables the switch
to dynamically control the MFS_Enable, VI_Enable and LCF_Enable features based
TABLE 6-9 Port Types
State Description
F_Port Fabric port — supports a single public device (N_Port).
FL_Port Fabric loop port — self discovers a single device (N_Port) or a loop of up to
126 public devices (NL_Port).
G_Port Generic port — self discovers as an F_Port or an E_Port.
GL_Port Generic loop port — self discovers as an F_Port, FL_Port, or an E_Port.
GL_Port is the default port type. A single device on a public loop will
attempt to configure as an F_Port first, then if that fails, as an FL_Port.
Donor Donor port — allows buffer credits to be used by another port.