Deployment Guide

• If the negotiation fails and PFC is enabled on the port, any user-congured PFC input policies are applied. If no PFC input policy has
been previously applied, the PFC default setting is used (no priorities congured). 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 buering 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 trac types in multiprotocol (Ethernet, FCoE,
SCSI) links.
ETS allows you to divide trac according to its 802.1p priority into dierent priority groups (trac classes) and congure bandwidth
allocation and queue scheduling for each group to ensure that each trac type is correctly prioritized and receives its required bandwidth.
For example, you can prioritize low-latency storage or server cluster trac in a trac class to receive more bandwidth and restrict best-
eort LAN trac assigned to a dierent trac class.
Although you can congure strict-priority queue scheduling for a priority group, ETS introduces exibility that allows the bandwidth
allocated to each priority group to be dynamically managed according to the amount of LAN, storage, and server trac in a ow. Unused
bandwidth is dynamically allocated to prioritized priority groups. Trac is queued according to its 802.1p priority assignment, while exible
bandwidth allocation and the congured queue-scheduling for a priority group is supported.
The following gure shows how ETS allows you to allocate bandwidth when dierent trac types are classed according to 802.1p priority
and mapped to priority groups.
Figure 132. Enhanced Transmission Selection
The following table lists the trac groupings ETS uses to select multiprotocol trac for transmission.
Table 96. 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.
948 FC Flex IO Modules