Reference Guide

Data Center Bridging (DCB) | 281
ETS Prerequisites and Restrictions
The following prerequisites and restrictions apply when you configure ETS bandwidth allocation or queue
scheduling and apply a QoS DCB Output policy on an interface:
• Configuring ETS bandwidth allocation or a queue scheduler for dot1p priorities in a priority group is
applicable only if the DCBX version used on a port is CIN (refer to Configuring DCBx on an
Interface).
• When allocating bandwidth or configuring a queue scheduler for dot1p priorities in a priority group on
a DCBX CIN interface, take into account the CIN bandwidth allocation (Configuring Bandwidth
Allocation for DCBX CIN) and dot1p-queue mapping (Table 15-1).
• Although an DCB Output policy does not support WRED, ECN, rate shaping, and rate limiting
because these parameters are not negotiated by DCBX with peer devices, you can apply a QoS output
policy with WRED and/or rate shaping on a DCBX CIN-enabled interface (refer to Configure
Port-based Rate Shaping on page 668 and Weighted Random Early Detection on page 678). In this
case, the WRED or rate shaping configuration in the QoS output policy should take into account the
bandwidth allocation or queue scheduler configured in the DCB Output policy.
• You can only use a QoS DCB Output policy in association with a priority group in a DCB output
policy and cannot be applied to an interface as a normal QoS output policy (refer to Applying an DCB
Output Policy for a Priority Group to an Interface and Create an output QoS policy on page 672).
Creating a QoS DCB Output Policy
A QoS output policy that you create to optimize bandwidth on an output interface for specified priority
traffic consists of the ETS settings used in DCBX negotiations with peer devices:
• Bandwidth percentage
• Queue scheduling
Note: The IEEE 802.1Qaz, CEE, and CIN versions of ETS are supported.