Monitoring Iscsi Traffic Flows; Application Of Quality Of Service To Iscsi Traffic Flows; Information Monitored In Iscsi Traffic Flows - Dell S4820T Configuration Manual

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.
You can configure whether the iSCSI optimization feature uses the VLAN priority or IP DSCP mapping to
determine the traffic class queue. By default, iSCSI flows are assigned to dot1p priority 4. To map
incoming iSCSI traffic on an interface to a dot1p priority-queue other than 4, use the CoS dot1p-
priority command (refer to
recommends setting the CoS dot1p priority-queue to 0 (zero).
You can configure whether iSCSI frames are re-marked to contain the configured VLAN priority tag or IP
DSCP when forwarded through the switch.
NOTE: On a switch in which a large proportion of traffic is iSCSI, CoS queue assignments may
interfere with other network control-plane traffic, such as ARP or LACP. Balance preferential
treatment of iSCSI traffic against the needs of other critical data in the network.

Information Monitored in iSCSI Traffic Flows

iSCSI optimization examines the following data in packets and uses the data to track the session and
create the classifier entries that enable QoS treatment.
• Initiator's IP Address
• Target's IP Address
• ISID (Initiator defined session identifier)
• Initiator's IQN (iSCSI qualified name)
• Target's IQN
• Initiator's TCP Port
• Target's TCP Port
• Connection ID
• Aging
• Up Time
If no iSCSI traffic is detected for a session during a user-configurable aging period, the session data is
cleared.
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QoS dot1p Traffic Classification and Queue Assignment). Dell Networking
iSCSI Optimization