Administrator Guide

• 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 congured priority group bandwidth is decremented based on the
congured 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 trac 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.
Conguring Enhanced Transmission Selection
ETS provides a way to optimize bandwidth allocation to outbound 802.1p classes of converged Ethernet trac.
Dierent trac types have dierent service needs. Using ETS, you can create groups within an 802.1p priority class to congure
dierent treatment for trac with dierent bandwidth, latency, and best-eort needs.
For example, storage trac is sensitive to frame loss; interprocess communication (IPC) trac is latency-sensitive. ETS allows
dierent trac types to coexist without interruption in the same converged link by:
• Allocating a guaranteed share of bandwidth to each priority group.
• Allowing each group to exceed its minimum guaranteed bandwidth if another group is not fully using its allotted bandwidth.
To congure ETS and apply an ETS output policy to an interface, you must:
1. Create a Quality of Service (QoS) output policy with ETS scheduling and bandwidth allocation settings.
2. Create a priority group of 802.1p trac classes.
3. Congure a DCB output policy in which you associate a priority group with a QoS ETS output policy.
4. Apply the DCB output policy to an interface.
Conguring DCB Maps and its Attributes
This topic contains the following sections that describe how to congure a DCB map, apply the congured DCB map to a port,
congure PFC without a DCB map, and congure lossless queues.
DCB Map: Conguration Procedure
A DCB map consists of PFC and ETS parameters. By default, PFC is not enabled on any 802.1p priority and ETS allocates equal
bandwidth to each priority. To congure user-dened PFC and ETS settings, you must create a DCB map.
Step
Task Command Command Mode
1
Enter global conguration mode to create a DCB map or
edit PFC and ETS settings.
dcb-map name
CONFIGURATION
2
Congure the PFC setting (on or o) and the ETS
bandwidth percentage allocated to trac in each priority
group, or whether the priority group trac should be
handled with strict priority scheduling. You can enable PFC
on a maximum of two priority queues on an interface.
Enabling PFC for dot1p priorities makes the corresponding
priority-group
group_num {bandwidth
percentage | strict-priority} pfc
{on | o}
DCB MAP
Data Center Bridging (DCB)
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