Administrator Guide

You can congure whether the iSCSI optimization feature uses the VLAN priority or IP DSCP mapping to determine the trac class queue.
By default, iSCSI ows are assigned to dot1p priority 4. To map incoming iSCSI trac on an interface to a dot1p priority-queue other than 4,
use the CoS dot1p-priority command (refer to QoS dot1p Trac Classication and Queue Assignment). Dell Networking
recommends setting the CoS dot1p priority-queue to 0 (zero).
You can congure whether iSCSI frames are re-marked to contain the congured VLAN priority tag or IP DSCP when forwarded through
the switch.
NOTE: On a switch in which a large proportion of trac is iSCSI, CoS queue assignments may interfere with other network
control-plane trac, such as ARP or LACP. Balance preferential treatment of iSCSI trac against the needs of other critical data
in the network.
Information Monitored in iSCSI Trac Flows
iSCSI optimization examines the following data in packets and uses the data to track the session and create the classier entries that
enable QoS treatment.
• Initiator’s IP Address
• Target’s IP Address
• ISID (Initiator dened session identier)
• Initiator’s IQN (iSCSI qualied name)
• Target’s IQN
• Initiator’s TCP Port
• Target’s TCP Port
• Connection ID
• Aging
• Up Time
If no iSCSI trac is detected for a session during a user-congurable aging period, the session data is cleared.
If more than 256 simultaneous sessions are logged continuously, the following message displays indicating the queue rate limit has been
reached:
%STKUNIT2-M:CP %iSCSI-5-ISCSI_OPT_MAX_SESS_EXCEEDED: New iSCSI Session Ignored: ISID -
400001370000 InitiatorName - iqn.1991-05.com.microsoft:dt-brcd-cna-2 TargetName -
iqn.2001-05.com.equallogic:4-52aed6-b90d9446c-162466364804fa49-wj-v1 TSIH - 0"
Detection and Auto-Conguration for Dell EqualLogic Arrays
The iSCSI optimization feature includes auto-provisioning support with the ability to detect directly connected Dell EqualLogic storage
arrays and automatically recongure the switch to enhance storage trac ows.
The switch uses the link layer discovery protocol (LLDP) to discover Dell EqualLogic devices on the network. LLDP is enabled by default.
For more information about LLDP, refer to Link Aggregation Control Protocol (LACP).
The following message displays the rst time a Dell EqualLogic array is detected and describes the conguration changes that are
automatically performed:
%STKUNIT0-M:CP %IFMGR-5-IFM_ISCSI_AUTO_CONFIG: This switch is being configured for optimal
conditions to support iSCSI traffic which will cause some automatic configuration to occur
including jumbo frames and flow-control on all ports; no storm control and spanning-tree port
fast to be enabled on the port of detection.
The following syslog message is generated the rst time an EqualLogic array is detected:
%STKUNIT0-M:CP %LLDP-5-LLDP_EQL_DETECTED: EqualLogic Storage Array detected on interface Te 1/
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