H3C S6850 Series, Руководство по настройке

Страница: 47 / 394

18
Restrictions and guidelines
WARNING!
After PFC is enabled for 802.1p priorities, the PFC thresholds use the default values, which are
adequate in typical network environments. As a practice, change the thresholds only when
necessary.
You must enable PFC for 802.1p priorities before setting the PFC thresholds.
If you cancel PFC threshold settings on an interface, the PFC thresholds are restored to the state
when only the
priority-flow-control no-drop dot1p
command is executed.
This feature does not support preprovisioning. For more information about preprovisioning, see
Fundamentals Configuration Guide .
Procedure
1. Enter system view.
system-view
2. Set the maximum number of cell resources in a headroom storage space.
priority-flow-control poolID pool-number headroom headroom-number
By default, the maximum number of cell resources in a headroom storage space is 12288.
3. Enter Ethernet interface view.
interface interface-type interface-number
4. Set the headroom buffer threshold.
priority-flow-control dot1p dot1p headroom headroom-number
By default, the headroom buffer threshold is 8192.
5. Set the back pressure frame triggering threshold.
{
Set the dynamic back pressure frame triggering threshold.
priority-flow-control dot1p dot1p ingress-buffer dynamic ratio
By default, no dynamic back pressure frame triggering thresholds are set.
{
Set the static back pressure frame triggering threshold.
priority-flow-control dot1p dot1p ingress-buffer static threshold
By default, the static back pressure frame triggering threshold is 512.
6. Set the offset between the back pressure frame stopping threshold and triggering threshold.
priority-flow-control dot1p dot1p ingress-threshold-offset
offset-number
By default, the offset between the back pressure frame stopping threshold and triggering
threshold is 48.
7. Set the PFC reserved threshold.
priority-flow-control dot1p dot1p reserved-buffer reserved-number
By default, the PFC reserved threshold is 6.
Configuring PFC deadlock detection
About PFC deadlock detection
When packets carrying the specified 802.1p priority are transmitted in a loop, packets in the data
buffer cannot be forwarded and PFC frames are repeatedly transmitted between devices. As a result,
the cell resources in the buffer for device interfaces always cannot be released. In this case, the
device enters the PFC deadlock state.