Administrator Guide

Unused bandwidth is dynamically allocated to prioritized priority groups. Trac is queued according to its 802.1p priority assignment,
while exible bandwidth allocation and the congured queue-scheduling for a priority group is supported.
The following gure shows how ETS allows you to allocate bandwidth when dierent trac types are classed according to 802.1p
priority and mapped to priority groups.
Figure 28. Enhanced Transmission Selection
The following table lists the trac groupings ETS uses to select multiprotocol trac for transmission.
Table 9. ETS Trac Groupings
Trac Groupings Description
Priority group A group of 802.1p priorities used for bandwidth allocation and
queue scheduling. All 802.1p priority trac in a group must have
the same trac handling requirements for latency and frame
loss.
Group ID A 4-bit identier assigned to each priority group. The range is
from 0 to 7.
Group bandwidth Percentage of available bandwidth allocated to a priority group.
Group transmission selection algorithm (TSA) Type of queue scheduling a priority group uses.
In the Dell Networking OS, ETS is implemented as follows:
• ETS supports groups of 802.1p priorities that have:
– PFC enabled or disabled
– No bandwidth limit or no ETS processing
• Bandwidth allocated by the ETS algorithm is made available after strict-priority groups are serviced. If a priority group does not
use its allocated bandwidth, the unused bandwidth is made available to other priority groups.
• For ETS trac selection, an algorithm is applied to priority groups using:
– Strict priority shaping
– ETS shaping
• ETS uses the DCB MIB IEEE 802.1azd2.5.
Data Center Bridging Exchange Protocol (DCBx)
DCBx allows a switch to automatically discover DCB-enabled peers and exchange conguration information. PFC and ETS use DCBx
to exchange and negotiate parameters with peer devices. DCBx capabilities include:
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Data Center Bridging (DCB)