Reference Guide

In an iSCSI session, a switch connects CNA servers (iSCSI initiators) to a storage array (iSCSI targets) in a storage area network (SAN) or
TCP/IP network. iSCSI optimization running on the switch uses dot1p priority-queue assignments to ensure that iSCSI trac receives
priority treatment.
iSCSI conguration notes
• When you enable iSCSI optimization, the switch auto-detects and auto-congures for Dell EqualLogic storage arrays directly connected
to an interface. iSCSI automatically congures switch parameters after connection to a storage device is veried. You must manually
enable an interface to support a storage device that is directly connected to a port, but not automatically detected by iSCSI.
• By default, iSCSI monitoring sessions listen on TCP ports 860 and 3260. Enable iSCSI session monitoring and the aging time for iSCSI
sessions.
• Congure the CoS/DSCP values applied to ingress iSCSI ows — create a class-iscsi class map in POLICY-CLASS-MAP mode.
• iSCSI operation requires LLDP to be enabled. The DCBX application TLV carries information about the dot1p priorities to use when
sending iSCSI trac. This informational TLV is packaged in LLDP PDUs. You can recongure the 802.1p priority bits advertised in the
TLVs.
Congure iSCSI optimization
The iSCSI protocol provides TCP/IP transport of storage trac between servers and storage arrays in a network using iSCSI commands.
1 Congure an interface or interface range to detect a connected storage device.
interface ethernet node/slot/port:[subport]
interface range ethernet node/slot/port:[subport]-node/slot/port[:subport]
2 Enable the interface to support a storage device that is directly connected to the port and not automatically detected by iSCSI. Use
this command for storage devices that do not support LLDP. The switch auto-detects and auto-congures Dell EqualLogic storage
arrays directly connected to an interface when you enable iSCSI optimization.
iscsi profile-storage storage-device-name
3 Congure DCBX to use LLDP to send iSCSI application TLVs with the dot1p priorities for iSCSI trac in INTERFACE mode.
lldp tlv-select dcbxp-appln iscsi
4 Return to CONFIGURATION mode.
exit
5 (Optional) If necessary, re-congure the iSCSI TCP ports and IP addresses of target storage devices in CONFIGURATION mode.
Separate TCP port numbers with a comma (0-65535; default 860 and 3260).
iscsi target port tcp-port1 [tcp-port2, ..., tcp-port16] [ip-address ip-address]
6 Congure the QoS policy applied to the ingress iSCSI ows. Apply the service policy to ingress interfaces in CONFIGURATION mode.
(Optional) Reset the default CoS dot1p priority (default 4) and/or the trusted DCSP value used for iSCSI trac. Assign an internal
qos-group queue (0 to 7) to dot1p (0 to 7) and DSCP (0 to 63) values in POLICY-CLASS-MAP mode.
class-map type application class-iscsi
policy-map type application policy-iscsi
class class-iscsi
set qos-group
traffic-class-number
set cos dot1p-priority
set dscp dscp-value
end
service-policy type application policy-iscsi
7 Enable iSCSI monitoring sessions on TCP ports in CONFIGURATION mode.
iscsi session-monitoring enable
8 (Optional) Set the aging time for the length of iSCSI monitoring sessions in CONFIGURATION mode (5 to 43,200 minutes; default
10).
iscsi aging time [minutes]
9 (Optional) Recongure the dot1p priority bits advertised in iSCSI application TLVs in CONFIGURATION mode. The default bitmap is
0x10 (dot1p 4). The default dot1p 4 value is sent in iSCSI application TLVs only if you enabled the PFC pause for dot1p 4 trac
(pfc-cos dot1p-priority command).
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