Administrator Guide

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.
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.
If more than 256 simultaneous sessions are logged continuously, the following message displays indicating the queue rate limit has been
reached:
%Z9500LC48:1 %ACL_AGENT-3-ISCSI_OPT_MAX_SESS_LIMIT_REACHED: Monitored iSCSI sessionsreached
maximum limit
NOTE:
If you are using EqualLogic or Compellent storage arrays, more than 256 simultaneous iSCSI sessions are
possible. However, iSCSI session monitoring is not capable of monitoring more than 256 simultaneous iSCSI sessions. If
this number is exceeded, sessions are not detected by the switch; but it does not affect forwarding. Dell Networking
recommends that you disable iSCSI session monitoring for EqualLogic and Compellent storage arrays or for installations
with more than 256 simultaneous iSCSI sessions.
Only sessions the switch observes are learned; sessions flowing through an adjacent switch are not learned. Session monitoring learns
sessions that actually flow through the switch, it does not learn all sessions in the entire topology.
After a switch is reloaded, any information exchanged during the initial handshake is not available. If the switch picks up the
communication after reloading, it would detect a session was in progress but could not obtain complete information for it. Any incomplete
information of this type would not be available in the show commands.
Detection and Auto-Configuration 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 reconfigure the switch to enhance storage traffic flows.
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 Layer Discovery Protocol (LLDP).
The following message displays the first time a Dell EqualLogic array is detected and describes the configuration changes that are
automatically performed:
%SYSTEM: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
490
iSCSI Optimization