Users Guide

Fabric OS Administrator’s Guide 147
53-1002920-02
Buffer credit recovery
5
Buffer credit recovery is enabled automatically across any long-distance connection for which the
E_Port, F_Port, or EX_Port buffer credit recovery mechanism is supported. For 16-Gbps FC devices
and blades (Brocade 6505, 6510, 6520, M6505, 6547, CR16-4, CR16-8, FC8-32E, FC8-48E,
FC16-32, FC16-48), you can use the portCfgCreditRecovery command to disable or enable buffer
credit recovery on a port.
Buffer credit recovery over an E_Port
To support buffer credit recovery, E_Ports must be connected between devices that support 16
Gbps or between devices that support 8 Gbps.
• Devices that support 16 Gbps:
- Brocade 6505, 6510, 6520, M6505, 6547
- FC8-32E, FC8-48E,FC16-32, FC16-48
• Devices that support 8 Gbps:
- Brocade 300, 5100, 5300, 5410, 5424, 5450, 5480, VA-40FC
- FC8-16, FC8-32, FC8-48
If a device that supports 16 Gbps is connected to a device that supports only 8 Gbps, buffer credit
recovery is disabled, even if both devices are running 8 Gbps.
The buffer credit recovery feature for E_Ports is enabled for the following flow-control modes:
• Normal (R_RDY)
• Virtual Channel (VC_RDY)
• Extended VC (EXT_VC_RDY)
Buffer credit recovery over an F_Port
Buffer credit recovery for F_Ports is supported for F_Port-to-N_Port links between a Brocade switch
and Access Gateway, between a Brocade switch and an adapter, and between an Access Gateway
and an adapter. For an F_Port on a Brocade switch connected to an Access Gateway, the following
conditions must be met:
• Both devices must run Fabric OS v7.1 or later.
• Fabric OS must support buffer credit recovery at either end of the link.
• If both devices support 16 Gbps, the flow-control mode can be either Normal mode (R_RDY) or
VC mode (VC_RDY); otherwise the flow-control mode must be R_RDY.
For an F_Port on a Brocade switch or Access Gateway connected to an adapter, the following
conditions must be met:
• The Brocade switch or Access Gateway must run Fabric OS v7.1 or later.
• Fabric OS must support buffer credit recovery at both ends of the link.
• The adapter must be running HBA v3.2 firmware or later.
• The adapter must operate at maximum speed.
• The flow-control mode must be R_RDY.
The feature is enabled automatically during a link reset if the conditions are met. If the conditions
for buffer credit recovery are not met, the link will come up, but buffer credit recovery will not be
enabled.