Reference Guide

Table 13. 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.
Data Center Bridging Exchange Protocol (DCBx)
The data center bridging exchange (DCBx) protocol is disabled by default on the S4810; ETS is also disabled.
DCBx allows a switch to automatically discover DCB-enabled peers and exchange configuration information. PFC and
ETS use DCBx to exchange and negotiate parameters with peer devices. DCBx capabilities include:
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