Performing Pfc Using Dscp Bits Instead Of 802.1P Bits - Dell C9000 Series Networking Configuration Manual

Field
Local DCBx Status: Acknowledgment Number
Local DCBx Status: Protocol State
Peer DCBx Status: DCBx Operational Version
Peer DCBx Status: DCBx Max Version Supported
Peer DCBx Status: Sequence Number
Peer DCBx Status: Acknowledgment Number
Total DCBx Frames transmitted
Total DCBx Frames received
Total DCBx Frame errors
Total DCBx Frames unrecognized
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.
Description
Acknowledgement number transmitted in Control
TLVs.
Current operational state of DCBx protocol: ACK or
IN-SYNC.
DCBx version advertised in Control TLVs received
from peer device.
Highest DCBx version supported in Control TLVs
received from peer device.
Sequence number transmitted in Control TLVs
received from peer device.
Acknowledgement number transmitted in Control
TLVs received from peer device.
Number of DCBx frames sent from local port.
Number of DCBx frames received from remote peer
port.
Number of DCBx frames with errors received.
Number of unrecognizable DCBx frames received.
Data Center Bridging (DCB) 332