Enhanced Transmission Selection (ETS) is the second part of the Data Center Bridging puzzle (I’ve already described Priority Flow Control). It specifies two different technologies:
- Queuing mechanisms in bridges
- Data Center Bridging eXchange protocol: a Control/Negotiation protocol that allows bridges and hosts to negotiate QoS parameters in a bridged network.
Although some bridges from some vendors supported numerous QoS mechanisms in the past, 802.1Qaz is the first attempt to standardize a richer set of QoS behaviors than the strict priority queuing defined in 802.1p.