Users Guide

• iSCSI QoS — A user-congured iSCSI class of service (CoS) prole is applied to all iSCSI trac. Classier rules are used to direct the
iSCSI data trac to queues that can be given preferential QoS treatment over other data passing through the switch. Preferential
treatment helps to avoid session interruptions during times of congestion that would otherwise cause dropped iSCSI packets.
• iSCSI DCBx TLVs are supported.
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 congured
to use dot1p priority-queue assignments to ensure that iSCSI trac in these sessions receives priority treatment when forwarded on
stacked switch hardware.
Figure 56. iSCSI Optimization Example
Monitoring iSCSI Trac Flows
The switch snoops iSCSI session-establishment and termination packets by installing classier 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 identies IP packets to or from these ports as iSCSI trac.
You can congure the switch to monitor trac 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.
iSCSI Optimization
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