Owner`s manual

160 | iSCSI Optimization
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• If you configured flow-control, iSCSI uses the current configuration. If you did not configure
flow-control, iSCSI auto-configures flow control.
• iSCSI monitoring sessions — the switch monitors and tracks active iSCSI sessions in connections on
the switch, including port information and iSCSI session information.
• iSCSI QoS — A user-configured iSCSI class of service (CoS) profile is applied to all iSCSI traffic.
Classifier rules are used to direct the iSCSI data traffic 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.
Figure 10-1 shows iSCSI optimization between servers in an M1000e enclosure and a storage array in
which an Aggregator connects installed servers (iSCSI initiators) to a storage array (iSCSI targets) in a
SAN network. iSCSI optimization running on the Aggregator is configured to use dot1p priority-queue
assignments to ensure that iSCSI traffic in these sessions receives priority treatment when forwarded on
Aggregator hardware.
Figure 10-1. 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. 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
numbers and target IP addresses, and you can remove the well-known port numbers from monitoring.