Deployment Guide

Figure 2. Enhanced Transmission Selection

The following table lists the trac groupings ETS uses to select multiprotocol trac for transmission.

Table 4. 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 so that the sum of the bandwidth use is 100%. If

priority group bandwidth use exceeds 100%, all congured priority group bandwidth is decremented based on the congured

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 trac 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)