Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) - Manual (Page 102)

FIGURE 6 New switch added to existing fabric
When connecting two switches together, Brocade recommends the best practice that the following
parameters are differentiated:
• Domain ID
• Switch name
• Chassis name
You must also verify the following fabric parameters are identical on each switch for a fabric to merge:
• R_A_TOV (Resource Allocation TimeOut Value)
• E_D_TOV (Error Detect TimeOut Value)
• Data Field Size
• Sequence Level Switching
• Disable Device Probing
• Suppress Class F Traffic
• Per-frame Route Priority
There are non-fabric parameters that must match as well, such as zoning. Some fabric services, such
as management server, must match. If the fabric service is enabled in the fabric, then the switch you
are introducing into the fabric must also have it enabled. If you experience a segmented fabric, refer to
the Fabric OS Troubleshooting and Diagnostics Guide to fix the problem.
Buffer credits
In order to prevent the dropping of frames in the fabric, a device can never send frames without the
receiving device being able to receive them, so an end-to-end flow control is used on the switch. Flow
control in Fibre Channel uses buffer-to-buffer credits, which are distributed by the switch. When all
buffer-to-buffer credits are utilized, a device waits for a VC_RDY or an R_RDY primitive from the
Buffer credits
102 Fabric OS Administrators Guide
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