Dell N3200-ON EMC Networking N-Series Switches CLI Reference Guide version 6.6 - Page 594

In general, the use of iSCSI CoS is not required. By default, iSCSI flows are assigned to the highest VPT/DSCP value that is mapped to the highest queue not used for stack management or the voice VLAN. Make sure you configure the relevant Class of Service parameters for the queue in order to complete the setting. Configuring the VPT/DSCP value sets the QoS profile which selects the egress queue to which the frame is mapped. The default setting for egress queues scheduling is Weighted Round Robin (WRR). You may alter the QoS setting by configuring the relevant ports to work in other scheduling and queue management modes via the Class of Service settings. These choices may include strict priority for the queue used for iSCSI traffic. The downside of strict priority is that, in certain circumstances (under heavy high priority traffic), other lower priority traffic may get starved. In WRR, the queue to which the flow is assigned to can be set to get the required percentage using the min-bandwidth settings. If an EqualLogic array is detected when QoS is enabled, two additional TCP ports receive preferential QoS treatment (TCP ports 25555 and 9876). This QoS policy is applied globally. The iscsi cos enable command enables the generation of the iSCSI Application Priority TLV over DCBX using the value set by the iscsi cos vpt command on switches that support DCBX. Example The following example configures iSCSI packets to receive CoS treatment using DiffServ Code Point AF 41 and configures remarking of transmitted iSCSI packets. console(config)#iscsi cos dscp 41 remark iscsi enable The iscsi enable command globally enables iSCSI optimization. To disable iSCSI optimization, use the no form of this command. Syntax iscsi enable no iscsi enable Layer 2 Switching Commands 594