Qlogic Storage Networking (Unified Fabric Pilot), Руководство по установке

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5–Validation Methods for DCB and FCoE
Validation Step 4—Validate PFC and Lossless Link
5-16 51031-00 A
3. To validate that PFC Pause frames are sent to reduce the traffic, configure
TraceControl to capture a large buffer when it encounters a PFC Pause
frame. To set up a capture:
a. Select the trigger mode.
b. Set up the trigger condition to capture on a PFC Pause frame and 80
percent of post-fill. The capture memory is a circular buffer that stops
capturing when 80 percent of the buffer is filled after the encountering
the trigger condition.
If TraceControl does not encounter the trigger condition on a PFC frame, it may be
because the Fibre Channel link is not saturated—increase the traffic rate until
TraceControl stops capturing. If the traffic throughput on the 10GigE link reaches
the theoretical maximum bandwidth, and TraceControl still does not encounter the
trigger condition, it may be because PFC is not properly configured, and the link is
not lossless. In this case, ensure that PFC is enabled, and restart the validation at
Step 1 .
When TraceControl stops capturing, it means that at least one PFC frame crossed
the link. Open the capture in Expert so that it analyzes all pauses in the trace, and
check for errors. Click
Report in the Expert tool bar to generate a report showing
the average and maximum pause times ( Table 5-2 ).
Validation Results
Figure 5-15 shows the captured PFC frames. The Cisco FCoE switch pauses the
FCoE traffic in the other direction using a PFC frame with the maximum pause
time (3,355 µs) at priority 3. The switch releases the pause by sending a PFC
frame with a zero pause time before the previous PFC frame expires. TraceView
measures the effective pause time to be 29.66 µs. In this case, no FCoE frame in
the other direction is being transmitted between the two PFC frames, which
indicates that the pause mechanism on the FCoE link is working as expected, and
is equivalent to the buffer-to-buffer credit mechanism on the Fibre Channel link.
Figure 5-15. Trace Shows the PFC Event to Pause the Transmitting FCoE Data
Frame Further