Wired

RoCEv2 now on 8325! 10.7 added IP ECN to 8325 so it is now officially RoCEv2 capable.

DCB standards

- Priority-based Flow Control (PFC): Provides a link level, flow control mechanism that can be independently controlled for each priority to eliminate data frame loss due to converged network congestion. The IEEE 802.1Qbb Priority-based Flow Control standard defined the operation of PFC. In conjunction with that standard, the IEEE 802.3bd Media Access Control Frame for Priority-based Flow Control standard amended IEEE 802.3 and defined the frame format to support IEEE 802.1Qbb Priority-based Flow Control. Both standards were approved on June 16, 2011.

- Enhanced Transmission Selection (ETS): Provides a common management framework for bandwidth assignment to traffic classes, allowing allocation of bandwidth to the different types of traffic sharing a converged network. The IEEE 802.1Qaz Enhanced Transmission Selection standard was approved on June 16, 2011.

- Data Center Bridging Exchange Protocol (DCBX): A discovery and capability exchange protocol used to convey capabilities and configurations of other data center bridging features between directly connected peers to ensure consistent configuration across the network. For instance, DCBX can be used to determine if two linked peer devices support PFC. DCBX can also be used to detect misconfiguration of a feature between linked peers. In addition, a DCBX device can use the information from its peer to configure its own DCB features to match the configuration of its linked peer. DCBX is defined in IEEE 802.1Qaz and uses functionality provided by the Link Layer Discovery Protocol through IEEE 802.1AB.

- IP Explicit Congestion Notification (ECN): IP ECN is a congestion notification protocol that, in times of congestion, throttles back traffic rather than pause it. IP ECN works over layer 3 and is considered a slow acting mechanism. When devices in an IP ECN fabric see congestion, they mark the traffic but they also send it on to the destination. When the destination sees the marking in the recieved packet it will respond to the initiator and inform it that they need to slow down the sending rate.

IP ECN works well in balancing the fairness of flows within a DCB network, as with PFC, a pause frame is sent to everyone within the same traffic classs even the ones barely sending traffic. IP ECN is used to balance out traffic flows while PFC can react to quicker burst and ensure those environments don't drop packets.