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1.3
System Configuration
As the fibre channel mode, the ANSI standard defines three modes: Arbitrated Loop, Fabric and
Point-to-Point. This drive supports Arbitrated Loop (FC-AL). Figure 1.4 shows an example of
the system configuration.
Initiator
(Node-1)
Drive
(Node-4)
The mode of connection of all devices to the fibre channel is called "node." The drive and
initiator correspond to the node shown in Figure 1.4. Each node has at least one port called "N-
port." In the FC-AL, a port is particularly called "node loop (NL) port." The MAF3364FC and
MAG series have two ports; one is connected to one FC-AL and a maximum of 126 NL ports can
be connected to one loop.
(1)
Loop configuration
One port incorporates a transmit circuit and receive circuit. Information is transmitted/received
by differential signals via electric signal lines. This pair of signal lines is called a link. Since
signals on a link are transmitted in one direction, wiring must be conducted so that it may form a
loop connection on the system.
In the case of the FC-AL interface, information is transmitted/received via each node connected
on a loop. Accordingly, if the power supply is off at a node connected to the loop or if interface
signals cannot be transmitted/received normally, the loop will no longer function. To avoid such
a nonconformity, a circuit called "port bypass circuit" is generally provided on the back plane of
the system. BC in Figure 1.4 shows this port bypass circuit.
(2)
Node addressing
Each node on the fibre channel loop is assigned its specific model number (SEL ID). The SEL
ID of the drive is set at the signal level on the back plane through 7 signals from SEL_0 to
SEL_6 of the SCA interface connector (CN1). In signal bit weighting, SEL_6 is the MSB
6
indicating 2
and SEL_0 is the LSB indicating 2
The SEL ID setting of the drive ranges from #0(x'00') to #125(x'7D').
1 - 8
Port B
BC
Port A
BC
Port B
BC
BC
Port A
Figure 1.4
FC-AL system configuration
C141-E078-02EN
Port B
BC
BC
Port A
Port B
BC
BC
Port A
0
.
Drive
(Node-2)
Drive
(Node-3)
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