Users Guide

iSCSI Optimization 641
iSCSI CoS and Priority Flow Control/Enhanced Transmission Selection
Interactions
When manually or automatically enabling the classification of iSCSI flows on
Dell EMC 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 EMC Networking N4000 Series
switches to originate iSCSI configuration information via DCBX. In this case,
enabling iSCSI CoS classification configures the Dell EMC Networking
N4000 Series switch to generate the iSCSI TLV via DCBX in support of
configuring directly connected storage and initiator devices. Dell EMC
Networking N4000 Series switches support both ETS and DCBx and support
DCB configuration in conjunction with Dell SAN 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 EMC Networking N4000 Series
switches only.