Administrator Guide
ETS Conguration Notes
ETS provides a way to optimize bandwidth allocation to outbound 802.1p classes of converged Ethernet trac. Dierent trac types have
dierent service needs. Using ETS, you can create groups within an 802.1p priority class to congure dierent treatment for tracs with
dierent bandwidth, latency, and best-eort needs.
When you congure ETS in a DCB map:
• The DCB map associates a priority group with a PFC operational mode (on or o) and an ETS scheduling and bandwidth allocation. You
can apply a DCB map on multiple egress ports.
• Use the ETS conguration associated with 802.1p priority trac in a DCB map in DCBx negotiation with ETS peers.
• Trac in priority groups is assigned to strict-queue or weighted round-robin (WRR) scheduling in an ETS conguration and is managed
using the ETS bandwidth-assignment algorithm. Dell Networking OS de-queues all frames of strict-priority trac before servicing any
other queues. A queue with strict-priority trac 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.
• Dell Networking OS supports hierarchical scheduling on an interface. The control trac on Dell Networking OS is redirected to control
queues as higher priority trac with strict priority scheduling. After the control queues drain out, the remaining data trac is scheduled
to queues according to the bandwidth and scheduler conguration in the DCB map. The available bandwidth calculated by the ETS
algorithm is equal to the link bandwidth after scheduling non-ETS higher-priority trac.
• The conguration 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 congure 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 trac: dot1p priority trac on the switch is scheduled to the current queue mapping. dot1p priorities within the
same queue must have the same trac properties and scheduling method.
• ETS conguration error: If an error occurs in an ETS conguration, the conguration 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 the bandwidth is
equally assigned to each dot1p priority.
If an error occurs when a port receives a peer’s ETS conguration, the port’s conguration resets to the ETS conguration in the previously
congured DCB map. If no DCB map was previously applied, the port resets to the default ETS parameters.
ETS Prerequisites and Restrictions
On the switch, ETS is enabled by default on Ethernet ports with equal bandwidth assigned to each 802.1p priority, when DCB is enabled.
You can change the default ETS conguration only by using a DCB map.
The following prerequisites and restrictions apply when you congure ETS bandwidth allocation or strict-priority queuing in a DCB map:
• When allocating bandwidth or conguring strict-priority queuing for dot1p priorities in a priority group on a DCBx CIN interface, take
into account the CIN bandwidth allocation and dot1p-queue mapping.
• Although ETS bandwidth allocation or strict-priority queuing does not support weighted random early detection (WRED), explicit
congestion notication (ECN), rate shaping, and rate limiting because these parameters are not negotiated by DCBx with peer devices,
you can apply a QoS output policy with WRED and/or rate shaping on a DCBx CIN-enabled interface. In this case, the WRED or rate
shaping conguration in the QoS output policy must take into account the bandwidth allocation or queue scheduler congured in the
DCB map.
• ETS is not supported on PE ports and C9010 cascade ports (member ports in the C9010 LAG created to connect to an attached
C1048P).
Data Center Bridging (DCB)
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