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Preliminary
Cable Fibre Channel Devices to the Switch
SANbox-16HA Fibre Channel Switch
2-10 Installation 59005-03 Rev. A Installer’s/User’s Manual
Distance
The maximum distance between each adapter and the Switch depends on the type
of GBICs and the type of cable installed. Refer to Appendix A Reference Informa-
tion for this information. Also, the speed and Fibre Channel Revision Level of each
adapter must be compatible with the Switch and the type of I/O media of each
adapter must be compatible with the particular GBIC on the Switch.
Port Buffer Credits
Each port has eight buffer credits. This allows a cable length up to 13 km at 1 Gbps
without performance degradation. Buffer credits can be extended for F_Ports and
T_Ports to maintain performance over longer cable lengths. Credits are extended
by chaining ports together. You can chain 1, 2, or 3 donor ports to the recipient
F_Port or T_Port adding 8 credits for each chained port. For example, chaining one
donor ports yields 16 credits, two donor ports yields 24 credits, and three donor
ports yields 32 credits.
To extend buffer credits, the switch must be cabled and configured properly. The
recipient F_Port or T_Port must be configured for extended credits using switch
management. The following rules apply when chaining ports:
• Credits can be extended only for F_Ports and T_Ports. The recipient F_Port
or T_Port must occupy the lowest numbered port in an ASIC group. For
example, port 1 or port 5 can be credit recipients, but not port 2. Refer to
“Tuning” on page 2-9 for information about ASIC groups.
• Define recipient ports by port mode using switch management. Port modes
for recipient F_Ports are: F_Ext16, F_Ext24, or F_Ext32. For example, to
extend credits for port 1 to 32 credits as an F_Port, define the port mode as
F_Ext32. Ports 2, 3, and 4 automatically become credit donors ports, and any
external connections to the donor ports are disabled. To chain T_Ports, define
recipient and donor ports as you would for an F_Port. When you cable the
T_Port, it will self-configure with extended credits.
• The recipient port and all donor ports must be members of the same ASIC
group. For example, you can chain ports 1 through 4, and 5 through 8, but not
3 through 6. Refer to “Tuning” on page 2-9 for information about ASIC
groups.
• Chained ports must be sequential. For example, if port 5 is the recipient port,
you can chain ports 5 and 6, but not 5 and 7.