Q-Logic 5600 manual Using the Extended Credits Wizard

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5 – Managing Ports Using the Extended Credits Wizard

5.3

Using the Extended Credits Wizard

Each 1/2/4-Gbps 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 the following distances:

„26 kilometers at 1-Gbps (0.6 credits per Km)

„13 kilometers at 2-Gbps (1.2 credits per Km)

„6 kilometers at 4-Gbps (2.4 credits/km)

Longer distances can be spanned at full bandwidth by borrowing credits from designated 1/2/4-Gbps 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, you can configure a 1/2/4-Gbps recipient port to borrow 15 credits from one donor port for a total of 30 credits (15+15=30). This will support communication over the following approximate distances:

„50 Km at 1-Gbps (30÷0.6)

„25 Km at 2-Gbps (30÷1.2)’

„12 km at 4-Gbps (30÷2.4)

Only 1/2/4-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 Figure 5-3. Match the number of ports needed with the number of designated donor ports. Click the Next button.

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