Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) - Manual (Page 130)

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.
Buffer credit recovery over an EX_Port
Buffer credit recovery is supported on a Fibre Channel router (FCR) EX_Port that connects over an
inter-fabric link (IFL) to an edge fabric E_Port when the following conditions are met:
• The FCR and the switch at the other end of the IFL must both run Fabric OS v7.1 or later.
• The FCR and the switch at either end of the IFL must both support 16 Gbps or 8 Gbps. Buffer credit
recovery is not supported if the EX_Ports do not support the same data rate.
• Either end of the IFL must support buffer credit recovery.
• If the inter-fabric link (IFL) connects devices that support 8 Gbps only, long-distance mode must
also be enabled. Long-distance mode can be enabled or disabled on devices that support 16 Gbps.
• Virtual Channel flow control (VC_RDY) or Extended VC flow control (EXT_VC_RDY) mode must be
in use. Buffer credit recovery is not supported for EX_Ports when normal (R_RDY) flow control
mode is in use.
The feature is enabled automatically during a link reset if the conditions are met. If the capabilities at
either end of the EX_Port-to-E_Port link are not matched, the link will come up, but refer to the Fabric
OS Command Reference for lists of devices and blades that support 16 Gbps and 8 Gbps.
Enabling and disabling buffer credit recovery
NOTE
By default, buffer credit recovery is not enabled on any of the platforms.
1. To disable buffer credit recovery on a port, perform the following steps.
a) Connect to the switch and log in using an account assigned to the admin role.
b) Enter the portCfgCreditRecovery command and include the -disable option.
Buffer credit recovery over an F_Port
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