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5 – Managing Ports
Configuring Ports
59022-03 D 5-11
5.2.4
Changing TL Modes
You can configure a TL_Port to support a loop of private target devices or a loop
of private initiator devices.
■ For a loop of private target devices, choose the TL Target radio button. This
enables up to 63 initiator devices anywhere in the fabric to automatically
connect with the private devices on the TL_Port. Use zoning to limit the
number of possible initiators to 63.
■ For a loop of private initiator devices, choose the TL Initiator radio button.
This enables the private initiators on the TL_Port to automatically connect to
up to 63 target devices. The TL_Port initiator devices and the target devices
must be members of the same soft zone.
5.2.5
Changing Buffer-to-Buffer Credits
Each SANbox2 port has a receive buffer capacity of 12 Fibre Channel frames or
credits which is equal to approximately 24K bytes. Port buffer credits can be
changed on ports to accommodate connections to non-SANbox2 switches that
have different port buffer capacities. To change port buffer credits, do the
following:
1. Select one or more ports in the faceplate display.
2. Open the Port menu and select Port Properties.
3. In the E_Port BB Credits field, enter the new number.
4. Choose the OK button to write the new buffer-to-buffer setting to the switch.
5.2.6
I/O Stream Guard
The I/O Stream Guard feature suppresses Registered State Control Notification
(RSCN) messages on a port basis.
5.2.7
Extending Port Credits
Each port is supported by a data buffer with a 12 credit capacity; that is, 12
maximum sized frames. For fibre optic cables, this enables full bandwidth class 2
service over a distance of 20 kilometers at 1 Gbps (0.6 credits/Km), or 10
kilometers at 2 Gbps (1.2 credits/Km). Longer distances can be spanned at full
bandwidth by borrowing credits from designated donor ports thus pooling the
buffer capacities. This is called credit extension. Each donor port contributes 11
credits to the pool from which the recipient ports can draw. For example, one
donor port contributes 11 credits to the pool from which a recipient draws for a
total of 23 credits (11+12). This provides approximately 38 Km at 1 Gbps (23÷0.6)
or 19 Km at 2 Gbps (23÷1.2).