Snmp Support For Pfc And Buffer Statistics Tracking; Generation Of Pfc For A Priority For Untagged Packets; Performing Pfc Using Dscp Bits Instead Of 802.1P Bits - Dell Z9500 Configuration Manual

a Enable DCB globally.
Dell(conf)#dcb enable
b Apply PFC Priority configuration. Configure priorities on which PFC is enabled.
SNMP Support for PFC and Buffer Statistics
Tracking
Buffer Statistics Tracking (BST) feature provides a mechanism to aid in Resource Monitoring and Tuning of Buffer Allocation.
The Max Use Count mode provides the maximum value of the counters accumulated over a period of time.
Priority Flow Control (PFC) provides a link level flow control mechanism, which is controlled independently for each frame
priority. The goal of this mechanism is to ensure zero loss under congestion in DCB networks.
Dell Networking OS provides SNMP support for monitoring PFC and BST counters, and statistics. The enhancement is made on
DELL-NETWORKING-FPSTATS-MIB with additional tables to display the PFC and BST counters and statistics.
The following tables are available in DELL-NETWORKING-FPSTATS-MIB:
• dellNetFpEgrQBuffSnapshotTable
• dellNetFpIngPgBuffSnapshotTable
• dellNetFpStatsPerPgTable
• dellNetPfcPerPrioTable
dellNetFpEgrQBuff This table fetches the BST statistics at Egress Port for the buffer used. This table displays the Snapshot of
SnapshotTable the Buffer cells used by Unicast and Multicast Data and Control Queues.
dellNetFpIngPgBuf This table fetches the BST statistics at the Ingress Port for the Shared Cells, and the Headroom cells used
fSnapshotTable per Priority Group. The snapshot of the Ingress Shared cells used and the Ingress Headroom cells used
per Priority Group, when PFC is enabled, display in this table. This table lists the linecard index, port
number and the priority group number.
dellNetFpStatsPerP This table fetches the Allocated Min cells, Shared cells, and Headroom cells per Priority Group, the mode
gTable in which the buffer cells are allocated — Static or Dynamic and the Used Min Cells, Shared cells and
Headroom cells per Priority Group. The table fetches a value of 0 if the mode of allocation is Static and a
value of 1 if the mode of allocation is Dynamic. This table lists thelinecard number, port number and
priority group number.
dellNetPfcPerPrioT This table fetches the number of PFC frames transmitted (PFC Requests) and the number of PFC frames
able received (PFC Indications) per priority on a per port basis. This table lists the linecard index, port number
and priority.
Generation of PFC for a Priority for Untagged
Packets
In order to generate PFC for a particular priority for untagged packets, and configuring PFC for that priority, you should find the
queue number associated with priority from TABLE 1 and Associate a DCB map to forward the matched DSCP packet to that
queue. PFC frames gets generated with PFC priority associated with the queue when the queue gets congested.
Performing PFC Using DSCP Bits Instead of 802.1p
Bits
Priority based Flow Control (PFC) is currently supported on Dell Networking OS for tagged packets based on the packet Dot1p.
In certain data center deployments, VLAN configuration is avoided on the servers and all packets from the servers are
untagged. These packets will carry IP header and can be differentiated based on the DSCP fields they carry on the server facing
switch ports. Requirement is to classify these untagged packets from the server based on their DSCP and provide PFC
treatment.
Dell Networking OS Releases 9.3(0.0) and earlier provide CLI support to specify the priorities for which PFC is enabled on each
port. This feature is applicable only for the tagged packets based on the incoming packet Dot1p and Dot1p based queue
Data Center Bridging (DCB) 247