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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 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 Exchange Protocol (DCBx)
The data center bridging exchange (DCBx) protocol is disabled by default on any switch on which PFC or ETS are enabled.
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:
● Discovery of DCB capabilities on peer-device connections.
● Determination of possible mismatch in DCB configuration on a peer link.
● Configuration of a peer device over a DCB link.
DCBx requires the link layer discovery protocol (LLDP) to provide the path to exchange DCB parameters with peer devices.
Exchanged parameters are sent in organizationally specific TLVs in LLDP data units. For more information, refer to Link Layer
Discovery Protocol (LLDP). The following LLDP TLVs are supported for DCB parameter exchange:
PFC parameters
PFC Configuration TLV and Application Priority Configuration TLV.
ETS parameters ETS Configuration TLV and ETS Recommendation TLV.
Creating a DCB Map
Configure the priority-based flow control (PFC) and enhanced traffic selection (ETS) settings in a DCB map before you can
apply them on downstream server-facing ports.
NOTE: This feature is supported only on PMUX mode.
1. Create a DCB map to specify the PFC and ETS settings for groups of dot1p priorities.
CONFIGURATION mode
dcb-map name
228
Data Center Bridging (DCB)