Administrator Guide

This cannot be inferred as the maximum supported iSCSI sessions are reached. Also, number of iSCSI sessions
displayed on the system may show any number equal to or less than the maximum.
The following illustration shows iSCSI optimization between servers and a storage array in which a stack of three switches connect
installed servers (iSCSI initiators) to a storage array (iSCSI targets) in a SAN network. iSCSI optimization running on the master switch is
configured to use dot1p priority-queue assignments to ensure that iSCSI traffic in these sessions receives priority treatment when
forwarded on stacked switch hardware.
Figure 62. iSCSI Optimization Example
Monitoring iSCSI Traffic Flows
The switch snoops iSCSI session-establishment and termination packets by installing classifier rules that trap iSCSI protocol packets to the
CPU for examination.
Devices that initiate iSCSI sessions usually use well-known TCP ports 3260 or 860 to contact targets. When you enable iSCSI
optimization, by default the switch identifies IP packets to or from these ports as iSCSI traffic.
You can configure the switch to monitor traffic for additional port numbers or a combination of port number and target IP address, and
you can remove the well-known port numbers from monitoring.
Application of Quality of Service to iSCSI Traffic Flows
You can configure iSCSI CoS mode. This mode controls whether CoS (dot1p priority) queue assignment and/or packet marking is
performed on iSCSI traffic.
When you enable iSCSI CoS mode, the CoS policy is applied to iSCSI traffic. When you disable iSCSI CoS mode, iSCSI sessions and
connections are still detected and displayed in the status tables, but no CoS policy is applied to iSCSI traffic.
iSCSI Optimization
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