Using The Extended Credits Wizard; Designate Donor Ports - Qlogic SANbox 5200 Series User Manual

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5.3

Using the Extended Credits Wizard

Each port is supported by a data-buffer with a 16-credit capacity; that is, 16
maximum sized frames. For fiber optic cables, this enables full bandwidth service
over a distance of 26 kilometers at 1-Gbps (0.6 credits per Km) or 13 kilometers at
2-Gbps (1.2 credits per 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 15 credits
to the pool from which the recipient ports can draw. The recipient port also loses
one credit in the process. For example, one donor port contributes 15 credits to
the pool from which a recipient draws for a total of 30 credits (15+15). This
provides approximately 50 Km at 1-Gbps (30÷0.6) or 25 Km at 2-Gbps (30÷1.2).
Only 1-Gbps/2-Gbps ports can donate or borrow credits. To extend credits, open
the Wizards menu and select Ext Credit Wizard. The Extended Credit Wizard
leads you through the following process to extend credits based on transmission
distance requirements:
1. Extended Distance: Explains the concepts and principles of extending port
credits. Click the Next button.
2. Extended Distance Requirements: Specify speed and distance requirements
for each port then click Next.
3. Designate Donor Ports: Select available ports and click >> to move the port
into the Selected Donor Port column shown in
of ports needed with the number of designated donor ports. Click the Next
button.
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Figure 5-3. Designate Donor Ports
5 – Managing Ports
Using the Extended Credits Wizard
Figure 5-3. Match the number
5-15