Concept Guide
• iSCSI QoS — A user-congured iSCSI class of service (CoS) prole is applied to all iSCSI trac. Classier rules are used to direct the
iSCSI data trac 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.
NOTE: After a switch is reloaded, powercycled, or upgraded, any information exchanged during the initial handshake is not
available. If the switch establishes communication after reloading, it detects that a session was in progress but could not obtain
complete information for it. Any incomplete information is not available in the show commands.
NOTE: After a switch is reloaded, powercycled, or upgraded, the system may display the ACL_AGENT-3-
ISCSI_OPT_MAX_SESS_LIMIT_REACHED: Monitored iSCSI sessions reached maximum limit log message. 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 congured
to use dot1p priority-queue assignments to ensure that iSCSI trac in these sessions receives priority treatment when forwarded on
stacked switch hardware.
Figure 62. iSCSI Optimization Example
iSCSI Optimization
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