Administrator Guide

iSCSI Optimization 579
iSCSI CoS and Priority Flow Control/Enhanced Transmission Selection
Interactions
When manually or automatically enabling the classification of iSCSI flows on
Dell Networking N4000 Series switches, enabling iSCSI CoS is not
recommended unless required as follows.
When using manual configuration of the switch or auto-configuration via
DCBX, the iSCSI packets are classified based on the user priority present in
the VLAN tag and, in this case, enabling iSCSI CoS classification via the
iSCSI command set provides no benefit. The only case for enabling iSCSI
CoS prioritization is when using Dell Networking N4000 Series switches to
originate iSCSI configuration information via DCBX. In this case, enabling
iSCSI CoS classification configures the Dell Networking N4000 Series switch
to generate the iSCSI TLV via DCBX in support of configuring directly
connected storage and initiator devices. Dell Networking N4000 Series
switches support both ETS and DCBx and support DCB configuration in
conjunction with EQL devices.
NOTE: If it is desired to utilize DCBX to configure lossless transport of iSCSI using
PFC, the operator MUST configure a non-default VLAN end-to-end in order to
transport the VLAN priority tag and ensure proper CoS treatment on every network
enabled device, including CNAs and the EQL arrays.
NOTE: The ETS feature is available on the Dell Networking N4000 Series
switches only.