Administrator Guide
Monitoring iSCSI Trac Flows
The switch snoops iSCSI session-establishment and termination packets by installing classier 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 identies IP packets to or from these ports as iSCSI trac.
You can congure the switch to monitor trac 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 Trac Flows
You can congure iSCSI CoS mode. This mode controls whether CoS (dot1p priority) queue assignment and/or packet marking is
performed on iSCSI trac.
When you enable iSCSI CoS mode, the CoS policy is applied to iSCSI trac. 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 trac.
You can congure whether the iSCSI optimization feature uses the VLAN priority or IP DSCP mapping to determine the trac class queue.
By default, iSCSI ows are assigned to dot1p priority 4. To map incoming iSCSI trac on an interface to a dot1p priority-queue other than 4,
use the
QoS dot1p-priority command (refer to QoS dot1p Trac Classication and Queue Assignment). Dell Networking
recommends setting the CoS dot1p priority-queue to 0 (zero).
You can congure whether iSCSI frames are re-marked to contain the congured VLAN priority tag or IP DSCP when forwarded through
the switch.
NOTE
: On a switch in which a large proportion of trac is iSCSI, CoS queue assignments may interfere with other network
control-plane trac, such as ARP or LACP. Balance preferential treatment of iSCSI trac against the needs of other critical data
in the network.
Information Monitored in iSCSI Trac Flows
iSCSI optimization examines the following data in packets and uses the data to track the session and create the classier entries that
enable QoS treatment.
• Initiator’s IP Address
• Target’s IP Address
• ISID (Initiator dened session identier)
• Initiator’s IQN (iSCSI qualied name)
• Target’s IQN
• Initiator’s TCP Port
• Target’s TCP Port
• Connection ID
• Aging
• Up Time
If no iSCSI trac is detected for a session during a user-congurable aging period, the session data is cleared.
iSCSI Optimization
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