Pfc And Ets Configuration Examples; Using Pfc To Manage Converged Ethernet Traffic; Configure Enhanced Transmission Selection - Dell Z9500 Configuration Manual

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.
Packet is assigned an internal priority on the ingress pipeline based on the queue to which it is destined. This Internal-priority to
Queue mapping has been modified and enhanced as follows for the device:
Table 17. Priority to Queue Mapping
0
Internal-
priority
2
Queue
Default dot1p to queue configuration is as follows:
Table 18. Dot1p to Queue Mapping
0
Packet-
Dot1p
2
Queue

PFC and ETS Configuration Examples

This section contains examples of how to configure and apply DCB policies on an interface.

Using PFC to Manage Converged Ethernet Traffic

To use PFC for managing converged Ethernet traffic, use the following command:
dcb-map linecard all backplane all dcb-map-name

Configure Enhanced Transmission Selection

ETS provides a way to optimize bandwidth allocation to outbound 802.1p classes of converged Ethernet traffic.
Different traffic types have different service needs. Using ETS, you can create groups within an 802.1p priority class to configure
different treatment for traffic with different bandwidth, latency, and best-effort needs.
For example, storage traffic is sensitive to frame loss; interprocess communication (IPC) traffic is latency-sensitive. ETS allows
different traffic types to coexist without interruption in the same converged link by:
• Allocating a guaranteed share of bandwidth to each priority group.
1 2
0 1
1 2
0 1
3 4
3 4
3 4
3 4
5 6
5 6
5 6
5 6
Data Center Bridging (DCB)
7
7
7
7
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