Administrator Guide

NOTE: The detail option display the current headroom pool usage in each of the Pipelines in the device.
Dell#show hardware buffer headroom-pool buffer-info
------Buffer Details for Stack-Unit 1 portpipe 0 ------
-----------------------------------------------------------------
Headroom-Pool Configured Buffer(KB) Used Buffer(KB)
-----------------------------------------------------------------
HP1 0 0
Dell#
Monitoring Buer Statistics for Tracking Purposes
Using the buer statistics tracking feature, you can monitor the peak buer usage of the head room pool over a specic period of time.
This monitoring enables you to optimize the head room pool size based on real-time network trac data.
To view the peak head room pool usage details during a specic monitoring period:
Enter the following show command:
EXEC Privilege Mode
show hardware buffer-stats-snapshot resource headroom-pool [detail]
NOTE: The detail option display the peak headroom pool usage in each of the Pipelines in the device.
Dell#show hardware buffer-stats-snapshot resource headroom-pool
---------------------------------------
HP# PEAK USE COUNT(CELLS)
---------------------------------------
0 0
1 0
2 0
3 0
Dell#
Behavior of Tagged Packets
The below is example for enabling PFC for priority 2 for tagged packets. Priority (Packet Dot1p) 2 will be mapped to PG6 on PRIO2PG
setting. All other Priorities for which PFC is not enabled are mapped to default PG – PG7.
Classication rules on ingress (Ingress FP CAM region) matches incoming packet-dot1p and assigns an internal priority (to select queue as
per Table 1 and Table 2).
The internal Priority assigned for the packet by Ingress FP is used by the memory management unit (MMU) to assign the packet to right
queue by indexing the internal-priority to queue map table (TABLE 1) in hardware.
PRIO2COS setting for honoring the PFC protocol packets from the Peer switches is as per above Packet-Dot1p->queue table (Table 2).
The packets come in with packet-dot1p 2 alone are assign to PG6 on ingress.
The packets come in with packet-dot1p 2 alone use Q2 (as per dot1p to Queue classication – Table 2) on the egress port.
• When Peer sends a PFC message for Priority 2, based on above PRIO2COS table (TABLE 2), Queue 2 is halted.
• Queue 2 starts buering the packets with Dot1p 2. This causes PG6 buer counter to increase on the ingress, since P-dot1p 2 is
mapped to PG6.
• As the PG6 watermark threshold is reached, PFC generats for dot1p 2.
Data Center Bridging (DCB)
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