Administrator Guide

Table 23. show interface DCBx detail Command Description (continued)
Field Description
Peer Operating version DCBx version that the peer uses to exchange DCB
parameters.
Local DCBx TLVs Transmitted Transmission status (enabled or disabled) of advertised DCB
TLVs (see TLV code at the top of the show command
output).
Local DCBx Status: DCBx Operational Version DCBx version advertised in Control TLVs.
Local DCBx Status: DCBx Max Version Supported Highest DCBx version supported in Control TLVs.
Local DCBx Status: Sequence Number Sequence number transmitted in Control TLVs.
Local DCBx Status: Acknowledgment Number Acknowledgement number transmitted in Control TLVs.
Local DCBx Status: Protocol State Current operational state of DCBx protocol: ACK or IN-SYNC.
Peer DCBx Status: DCBx Operational Version DCBx version advertised in Control TLVs received from peer
device.
Peer DCBx Status: DCBx Max Version Supported Highest DCBx version supported in Control TLVs received
from peer device.
Peer DCBx Status: Sequence Number Sequence number transmitted in Control TLVs received from
peer device.
Peer DCBx Status: Acknowledgment Number Acknowledgement number transmitted in Control TLVs
received from peer device.
Total DCBx Frames transmitted Number of DCBx frames sent from local port.
Total DCBx Frames received Number of DCBx frames received from remote peer port.
Total DCBx Frame errors Number of DCBx frames with errors received.
Total DCBx Frames unrecognized Number of unrecognizable DCBx frames received.
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
classification. This document will discuss the configurations required to support PFC for untagged packets based on incoming
packet DSCP.
For the tagged packets, Queue is selected based on the incoming Packet Dot1p. When PFC frames for a specific priority is
received from the peer switch, the queue corresponding to that Dot1p is halted from scheduling on that port, thus honoring the
PFC from the peer. If a queue is congested due to packets with a specific Dot1p and PFC is enabled for that Dot1p, switch will
transit out PFC frames for that Dot1p. The packet Dot1p to Queue mapping for classification on the ingress must be same as the
mapping of Dot1p to the Queue to be halted on the egress used for PFC honoring. Dell Networking OS ensures that these
mappings are identical. This section discusses the Dell Networking OS configurations needed for above PFC generation and
honoring mechanism to work for the untagged packets.
PRIORITY to PG mapping (PRIO2PG) is on the ingress for each port. By default, all priorities are mapped to PG7. A priority for
which PFC has to be generated is assigned to a PG other than PG7 (say PG6) and buffer watermark is set on PG6 so as to
generate PFC.
In ingress, the buffers are accounted at per PG basis and would indicate the number of the packets that has ingress this port
PG but still queued up in egress pipeline. However, there is no direct mapping between the PG and Queue.
Data Center Bridging (DCB)
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