iSCSI Commands 237iscsi cosThe iscsi cos Global Configuration mode command sets the quality of service profile that will be appliedto iSCSI flows. Use the no form of this command to return to default.Syntax• iscsi cos {vpt vpt | dscp dscp} [remark]• no iscsi cos• vpt/dscp — The Virtual Priority Tag (VPT) or DSCP to which the iSCSI frames are assigned.• remark — Mark the iSCSI frames with the configured VPT/DSCP when egressing the switch.Default ConfigurationThis command has no default configuration.Command ModeGlobal Configuration mode.User Guidelines• iSCSI flows are assigned by default with a VPT/DSCP mapped to the highest queue not used for stackmanagement or Voice VLAN (if mapping not changed by the user). The user should also take care ofconfiguring the relevant (VPT to queue/DSCP to queue) table in order to complete the setting.• Setting the VPT/DSCP sets the QoS profile, which determines the egress queue to which the frame ismapped. The switch default setting for egress queues scheduling is strict priority. The downside ofstrict priority is that, in certain circumstances (under heavy high priority traffic), other lower prioritytraffic may get starved. In WRR the queue to which the flow is assigned to can be set to get therequired percentage. The user must complete the QoS setting by configuring the relevant ports towork in WRR mode with the adequate weights.ExampleThe following example sets the quality of service profile that will be applied to iSCSI flows.iscsi aging timeThe iscsi aging-time Global Configuration mode command sets aging time for iSCSI sessions. Use theno form of this command to cancel aging.Console (config)# iscsi cos vpt 5 remark5400_CLI.book Page 237 Wednesday, December 17, 2008 4:33 PM
