HP StorageWorks 8/20q and SN6000 Fibre Channel Switch Enterprise Fabric Management Suite User Guide (5697-0420, June 2010)

140 Managing Ports
from one donor port for a total of 30 credits (15+15=30). This supports communication over the following
approximate distances:
• 50 km at 1 Gb/s (30÷0.6)
• 25 km at 2 Gb/s (30÷1.2)
• 12 km at 4 Gb/s (30÷2.4)
• 6 km at 8 Gb/s (30÷4.8)
Extending credits requires a minimum cable length that is dependent on transmission speed, but is
independent of the number of credits borrowed. Extending credits using short cables can cause excessive
port resets. Table 37 describes the minimum cable lengths for a port with extended credits.
NOTE: Supported distances are also dependent on the selection of SFP (shortwave or longwave) and the
type of fiber cable. See the Fibre Channel distance rules in the HP StorageWorks SAN Design Reference
Guide available at the HP website http://www.hp.com/go/sandesignguide
.
The Extended Credit wizard leads you through the following process to extend credits based on
transmission distance requirements. To extend credits:
1. Select a switch from the fabric tree.
2. Select Wizards > Extended Credit Wizard to open the Extended Credit Wizard dialog box (Figure 82).
• Extended Distance—Explains the concepts and principles of extending port credits. Click Next.
• Extended Distance Requirements—Specify speed and distance requirements for each port. Click
Next.
• Designate Donor Ports—Select available ports, and click >> to move the port into the Selected
Donor Port column. Match the number of ports needed with the number of designated donor ports.
Click Next.
• Verify requested changes—Review the extended distance requests and the selected donor ports.
Click Finish to apply the changes and redistribute the credits.
Figure 82 Extended Credit Wizard dialog box
Table 37 Extended Credits—Minimum Cable Lengths
Transmission Speed Minimum Cable Length
1 Gb/s 3 km
2 Gb/s 1.5 km
4 Gb/s 0.75 km
8 Gb/s 0.37 km