How Iscsi Sessions Are Translated - Brocade Communications Systems A7533A - Brocade 4Gb SAN Switch Base Administrator's Manual

How iSCSI sessions are translated

The iSCSI gateway enables applications on an IP network to use an iSCSI initiator to connect to FC
targets. The iSCSI gateway translates iSCSI protocol to Fibre Channel Protocol (FCP), bridging the IP
network and FC SAN. The following figure shows a basic implementation.
iS C S I
initiator
IP
network
FIGURE 2
The Brocade FC4-16IP blade acts as an iSCSI gateway between FC-attached targets and iSCSI
initiators. On the iSCSI initiator, iSCSI is mapped between the SCSI driver and the TCP/IP stack. At
the iSCSI gateway port, the incoming iSCSI data is converted to FCP (SCSI on FC) by the iSCSI
virtual initiator, and then forwarded to the FC target. This allows low-cost servers to leverage an
existing FC infrastructure.
To represent all iSCSI initiators and sessions, each iSCSI portal has one iSCSI virtual initiator (VI) to
the FC fabric that appears as an N_Port device with a special WWN format. Regardless of the
number of iSCSI initiators or iSCSI sessions sharing the portal, Fabric OS uses one iSCSI VI per
iSCSI portal.
The following figure shows the interaction of different layers from the iSCSI initiator stack to the FC
target stack, including the iSCSI gateway service used during protocol translation.
Application
iS C S I initiator
FIGURE 3
iSCSI Gateway Service Administrator's Guide
53-1000603-01
F C 4-16IP iS C S I gateway
IP
portal
iS C S I virtual
target (V T )
iSCSI gateway service basic implementation
S C S I
iS C S I
T C P /IP T C P /IP
iS C S I virtual
target (V T )
iSCSI-to-FC translation
Overview of iSCSI gateway service
iS C S I virtual
initiator (V I)
IP F C
iS C S I F C P (F C -4)
F C (F C -2/F C -3)
iS C S I virtual
initiator (V I)
iS C S I gateway s ervic e
1
F C
target 1
L UNs
S A N
L UNs
F C
target 2
S torage
(device s erver)
S C S I
F C P
F C
F C target
40. 3
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