Addendum

Table 12. ETS Traffic Groupings
Traffic Groupings Description
Priority group A group of 802.1p priorities used for bandwidth
allocation and queue scheduling. All 802.1p priority
traffic in a group must have the same traffic
handling requirements for latency and frame loss.
Group ID A 4-bit identifier 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 FTOS, 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.
Bandwidth is distributed in the following ways:
– If bandwidth is not assigned to the priority groups, all available bandwidth is equally distributed
among the priority groups. For example, if there are two priority groups, each will be assigned 50%
of the available bandwidth; if there are four priority groups, each group is assigned 25% of the
available bandwidth so that bandwidth use is always 100%.
– If a priority group does not use its allocated bandwidth, the unused bandwidth is made available to
other priority groups so that the sum of the bandwidth use is 100%.
– If priority group bandwidth is less than 100%, all configured priority group bandwidth is
incremented based on the configured percentage ratio until all priority group bandwidth use is
100%.
– If priority group bandwidth use exceeds 100%, all configured priority group bandwidth is
decremented based on the configured percentage ratio until all priority group bandwidth use is
100%.
– If priority group bandwidth usage is greater than or equal to 100% and any default priority groups
exist, then a minimum of 1% bandwidth use is assigned by decreasing 1% of bandwidth from the
other priority groups until priority group bandwidth use is 100%.
NOTE: You must configure at least one ETS priority group to a DCB output policy.
• For ETS traffic selection, an algorithm is applied to priority groups using:
– Strict priority shaping
– ETS shaping
– (Credit-based shaping is not supported.)
• ETS uses the DCB MIB IEEE 802.1azd2.5.
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Data Center Bridging (DCB)