Setup Guide

By default, all 802.1p priorities are grouped in priority group 0 and 100% of the port bandwidth is assigned to priority group 0. The complete
bandwidth is equally assigned to each priority class so that each class has 12 to 13%.
The maximum number of priority groups supported in ETS output policies on an interface is equal to the number of data queues (4) (8)on
the port. The 802.1p priorities in a priority group can map to multiple queues.
If you congure more than one priority queue as strict priority or more than one priority group as strict priority, the higher numbered priority
queue is given preference when scheduling data trac.
If multiple lossful priorities are mapped to a single priority group (PG1) and lossless priorities to another priority group (PG0), then
bandwidth split across lossful priorities is not even.
ETS Operation with DCBx
The following section describes DCBx negotiation with peer ETS devices.
In DCBx negotiation with peer ETS devices, ETS conguration is handled as follows:
• ETS TLVs are supported in DCBx versions CIN, CEE, and IEEE2.5.
• The DCBx port-role congurations determine the ETS operational parameters (refer to Congure a DCBx Operation).
• ETS congurations received from TLVs from a peer are validated.
• If there is a hardware limitation or TLV error:
– DCBx operation on an ETS port goes down.
– New ETS congurations are ignored and existing ETS congurations are reset to the default ETS settings.
• ETS operates with legacy DCBx versions as follows:
– In the CEE version, the priority group/trac class group (TCG) ID 15 represents a non-ETS priority group. Any priority group
congured with a scheduler type is treated as a strict-priority group and is given the priority-group (TCG) ID 15.
Conguring ETS in a DCB Map
A switch supports the use of a DCB map in which you congure enhanced transmission selection (ETS) setting. To congure ETS
parameters, you must apply a DCB map on an interface.
ETS Conguration Notes
ETS provides a way to optimize bandwidth allocation to outbound 802.1p classes of converged Ethernet trac. Dierent trac types have
dierent service needs. Using ETS, you can create groups within an 802.1p priority class to congure dierent treatment for tracs with
dierent bandwidth, latency, and best-eort needs.
When you congure 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 conguration associated with 802.1p priority trac in a DCB map in DCBx negotiation with ETS peers.
• Trac in priority groups is assigned to strict-queue or weighted round-robin (WRR) scheduling in an ETS conguration and is managed
using the ETS bandwidth-assignment algorithm. Dell EMC Networking OS de-queues all frames of strict-priority trac before servicing
any other queues. A queue with strict-priority trac 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 EMC Networking OS supports hierarchical scheduling on an interface. The control trac on Dell EMC Networking OS is redirected
to control queues as higher priority trac with strict priority scheduling. After the control queues drain out, the remaining data trac is
Data Center Bridging (DCB)
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