Users Guide

Table Of Contents
iSCSI Optimization 665
When iSCSI CoS mode is enabled, iSCSI login sessions up to the switch
limits are tracked, and data packets for those sessions are given the configured
CoS treatment. iSCSI sessions in excess of the switch limits are not given the
configured CoS treatment; therefore, it is not advisable to exceed the iSCSI
session limit. Multiple connections within a session are counted against the
session limit, even though they show in the session table as a single session.
Whether the iSCSI optimization feature uses the VLAN priority or IP DSCP
mapping to determine the traffic class queue is configurable. By default,
iSCSI flows are assigned to the highest VLAN priority tag or DSCP value
mapped to the highest queue not used for stack management or voice VLAN.
Use the classofservice dot1p-mapping command or the Quality of Service
Class of Service
Mapping Table Configuration page to configure the
relevant Class of Service parameters for the queue in order to complete the
setting.
Whether iSCSI frames are remarked to contain the configured VLAN priority
tag or the IP DSCP value when forwarded through the switch is configurable.
How Does iSCSI Optimization Use ACLs?
iSCSI Optimization borrows ACL lists from the global system pool. ACL lists
allocated by iSCSI Optimization reduce the total number of ACLs available
for use by the network operator. Enabling iSCSI Optimization uses one ACL
list to monitor for iSCSI sessions. Each monitored iSCSI session utilizes two
rules from additional ACL lists up to a maximum of two ACL lists. This
means that the maximum number of ACL lists allocated by iSCSI is three.
What Information Does the Switch Track in iSCSI Traffic Flows?
Packets are examined to find the following data, which is used in tracking the
session and creating 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