priorities configured). If you do not enable PFC on an interface, you can enable the 802.3x link-
level pause function. By default, the link-level pause is disabled.
• PFC supports buffering to receive data that continues to arrive on an interface while the remote
system reacts to the PFC operation.
• PFC uses the DCB MIB IEEE802.1azd2.5 and the PFC MIB IEEE802.1bb-d2.2.
Enhanced Transmission Selection
Enhanced transmission selection (ETS) supports optimized bandwidth allocation between traffic types in
multiprotocol (Ethernet, FCoE, SCSI) links.
ETS allows you to divide traffic according to its 802.1p priority into different priority groups (traffic
classes) and configure bandwidth allocation and queue scheduling for each group to ensure that each
traffic type is correctly prioritized and receives its required bandwidth. For example, you can prioritize
low-latency storage or server cluster traffic in a traffic class to receive more bandwidth and restrict best-
effort LAN traffic assigned to a different traffic class.
Although you can configure strict-priority queue scheduling for a priority group, ETS introduces flexibility
that allows the bandwidth allocated to each priority group to be dynamically managed according to the
amount of LAN, storage, and server traffic in a flow. Unused bandwidth is dynamically allocated to
prioritized priority groups. Traffic is queued according to its 802.1p priority assignment, while flexible
bandwidth allocation and the configured queue-scheduling for a priority group is supported.
The following figure shows how ETS allows you to allocate bandwidth when different traffic types are
classed according to 802.1p priority and mapped to priority groups.
Figure 140. Enhanced Transmission Selection
The following table lists the traffic groupings ETS uses to select multiprotocol traffic for transmission.
Table 78. 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
1044 FC Flex IO Modules