Reference Guide

You can configure the size of the PFC buffer for all switches in a stack or all port pipes on a specified stack unit by
entering the following commands on the master switch.
• Configure the PFC buffer for all switches in the stack.
CONFIGURATION mode
[no] dcb stack-unit all pfc-buffering pfc-port {1-64} pfc-queues {1-2}
By default, the PFC buffer is enabled on all ports on the stack unit.
• Configure the PFC buffer for all port pipes in a specified stack unit by specifying the port-pipe number, number of
PFC-enabled ports, and number of configured lossless queues.
CONFIGURATION mode
[no] dcb stack-unit stack-unit-id [port-set port-set-id] pfc-buffering pfc-
ports {1-64} pfc-queues {1-2}
Valid stack-unit IDs are 0 to 5.
The only valid port-set ID (port-pipe number) is 0.
FTOS Behavior: If you configure PFC on a 40GbE port, count the 40GbE port as four PFC-enabled ports in the pfc-port
number you enter in the command syntax.
To achieve lossless PFC operation, the PFC port count and queue number used for the reserved buffer size that is
created must be greater than or equal to the buffer size required for PFC-enabled ports and lossless queues on the
switch.
For the PFC buffer configuration to take effect, you must reload the stack or a specified stack unit (use the reload
command at EXEC Privilege level).
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.
• Allowing each group to exceed its minimum guaranteed bandwidth if another group is not fully using its allotted
bandwidth.
To configure ETS and apply an ETS output policy to an interface, you must:
1. Create a Quality of Service (QoS) output policy with ETS scheduling and bandwidth allocation settings.
2. Create a priority group of 802.1p traffic classes.
3. Configure a DCB output policy in which you associate a priority group with a QoS ETS output policy.
4. Apply the DCB output policy to an interface.
ETS Prerequisites and Restrictions
The following prerequisites and restrictions apply when you configure ETS bandwidth allocation or queue scheduling
and apply a QoS ETS output policy on an interface.
• Configuring ETS bandwidth allocation or a queue scheduler for dot1p priorities in a priority group is applicable if
the DCBx version used on a port is CIN (refer to Configuring DCBx) or CEE as a port version where CNA supports
CEE and DUT port versions in AUTO or CEE mode.
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