Addendum

• You cannot enable PFC and link-level flow control at the same time on an interface.
ETS Configuration Notes
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.
When you configure ETS in a DCB map:
• The DCB map associates a priority group with a PFC operational mode (on or off) and an ETS
scheduling and bandwidth allocation. You can apply a DCB map on multiple egress ports.
• Use the ETS configuration associated with 802.1p priority traffic in a DCB map in DCBx negotiation
with ETS peers.
• Traffic in priority groups is assigned to strict-queue or weighted round-robin (WRR) scheduling in an
ETS configuration and is managed using the ETS bandwidth-assignment algorithm. FTOS de-queues
all frames of strict-priority traffic before servicing any other queues. A queue with strict-priority traffic
can starve other queues in the same port.
• ETS-assigned bandwidth allocation and strict-priority scheduling apply only to data queues, not to
control queues.
• FTOS supports hierarchical scheduling on an interface. FTOS control traffic is redirected to control
queues as higher priority traffic with strict priority scheduling. After the control queues drain out, the
remaining data traffic is scheduled to queues according to the bandwidth and scheduler configuration
in the DCB map. The available bandwidth calculated by the ETS algorithm is equal to the link
bandwidth after scheduling non-ETS higher-priority traffic.
• The configuration of bandwidth allocation and strict-queue scheduling is not supported at the same
time for a priority group.
• Bandwidth assignment: By default, equal bandwidth is assigned to each dot1p priority in a priority
group. To configure the bandwidth assigned to the port queues associated with dot1p priorities in a
priority group, use the bandwidth percentage parameter. The sum of the bandwidth allocated to all
priority groups in a DCB map must be 100% of the bandwidth on the link. You must allocate at least
1% of the total bandwidth to each priority group.
• Scheduling of priority traffic: dot1p priority traffic on the switch is scheduled to the current queue
mapping. dot1p priorities within the same queue must have the same traffic properties and scheduling
method.
• ETS configuration error: If an error occurs in an ETS configuration, the configuration is ignored and
the scheduler and bandwidth allocation settings are reset to the ETS default value: 100% of available
bandwidth is allocated to priority group 0 and bandwidth is equally assigned to each dot1p priority.
If an error occurs when a port receives a peer’s ETS configuration, the port’s configuration resets to the
ETS configuration in the previously configured DCB map. If no DCB map was previously applied, the port
resets to the default ETS parameters.
ETS Prerequisites and Restrictions
On an S6000 switch, ETS is enabled by default on Ethernet ports; equal bandwidth is assigned to each
802.1p priority. You can change the default ETS configuration only by using a DCB map. For more
information, see Configuring DCB Maps and its Attributes.
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Data Center Bridging (DCB)