Users Guide

Figure 2. Enhanced Transmission Selection

The following table lists the traffic groupings ETS uses to select multiprotocol traffic for transmission.

Table 4. 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 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 so that the sum of the 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 less than or equal to 100% and any

default priority groups exist, 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%.

• 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 (DCB)