Administrator Guide

other priority groups so that the sum of the bandwidth use is 100%. If priority group bandwidth use

exceeds 100%, all configured priority group bandwidth is decremented based on the configured

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 traffic 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.

Configuring Enhanced Transmission Selection

ETS provides a way to optimize bandwidth allocation to outbound 802.1p classes of converged Ethernet

traffic.

Different traffic types have different service needs. Using ETS, you can create groups within an 802.1p

priority class to configure different treatment for traffic with different bandwidth, latency, and best-effort

needs.

For example, storage traffic is sensitive to frame loss; interprocess communication (IPC) traffic is latency-

sensitive. ETS allows different traffic 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 configure 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 traffic classes.

3. Configure 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.

Configuring DCB Maps and its Attributes

This topic contains the following sections that describe how to configure a DCB map, apply the

configured DCB map to a port, configure PFC without a DCB map, and configure lossless queues.

DCB Map: Configuration 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 configure user-defined PFC and ETS settings, you

must create a DCB map.

Data Center Bridging (DCB)