Dell S6000 FTOS 9.0(2.0) Configuration Guide for the System - Page 308

www.dell.com | support.dell.com FTOS Behavior: Create a DCB output policy to associate a priority group with an DCB Output policy with scheduling and bandwidth configuration. You can apply a DCB output policy on multiple egress ports. The ETS configuration associated with 802.1p priority traffic in a DCB output policy is used in DCBX negotiation with ETS peers. When you apply an DCB Output policy to an interface, ETS-configured scheduling and bandwidth allocation take precedence over any configured settings in the QoS output policies. To remove an DCB Output policy from an interface, use the no dcb-policy output policy-name command. ETS is enabled by default with the default ETS configuration applied (all dot1p priorities in the same group with equal bandwidth allocation). If you disable ETS in an output policy applied to an interface (the no ets mode on command), any previously configured QoS settings at the interface or global level take effect. If QoS settings are configured at the interface or global level and in an output policy map (the service-policy output command), the QoS configuration in the output policy take precedence. When you apply a DCB output policy with ETS bandwidth allocation to an egress interface which uses default ETS settings, the configured bandwidth allocation may not be applied to dot1p priority traffic in the specified priority group. ETS Operation with DCBX In DCBX negotiation with peer ETS devices, ETS configuration is handled as follows: • ETS TLVs are supported in DCBX versions CIN, CEE, and IEEE2.5. • ETS operational parameters are determined by the DCBX port-role configurations (Configuring DCBx Operation). • ETS configurations received from TLVs from a peer are validated. • In case of a hardware limitation or TLV error: • DCBX operation on an ETS port goes down. • New ETS configurations are ignored and existing ETS configurations are reset to the previously configured DCB Output policy on the port or to the default ETS settings if no DCB Output policy was previously applied. • ETS operates with legacy DCBX versions as follows: • In the CEE version, the priority group/traffic class group (TCG) ID 15 represents a non-ETS priority group. Any priority group configured with a scheduler type is treated as a strict-priority group and is given the priority-group (TCG) ID 15. • The CIN version supports two types of strict-priority scheduling: - Group strict priority: Allows a single priority flow in a priority group to increase its bandwidth usage to the bandwidth total of the priority group. A single flow in a group can use all the bandwidth allocated to the group. - Link strict priority: Allows a flow in any priority group to increase to the maximum link bandwidth. CIN supports only the dot1p priority-queue assignment in a priority group. To configure a dot1p priority flow in a priority group to operate with link strict priority, you must configure: 286 | Data Center Bridging (DCB)