Topologies; Arbitrated Loop; Private Arbitrated Loop; Public Arbitrated Loop - Sun Microsystems storagetek sl500 Reference Manual

Topologies

Topologies
StorageTek libraries support the following topologies with single port attachment:
Arbitrated Loop—private loop
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Arbitrated Loop—public loop
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Direct fabric attachment
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Arbitrated Loop

In a Fibre Channel arbitrated loop, as with the SCSI protocol, when devices want to
communicate on the bus, they must arbitrate and win the connection before
communications can begin. Once a device is powered on and initialized on the
loop, it must arbitrate and win to be able to communicate with other devices on the
loop.

Private Arbitrated Loop

If the arbitrated loop is not attached to a Fibre Channel fabric (that is, to an
F*_port), it is a private loop. A private arbitrated loop can connect up to 126
NL_ports. Again only point-to-point communication is possible between one
initiator and one target at any time. (Other links on the loop act as repeaters.) In
addition, initiator and target must reside within the same loop. Its best
implementation includes a Fibre Channel hub (see
page 35).

Public Arbitrated Loop

If the arbitrated loop contains at least one FL_port—that is, is attached to a Fibre
Channel fabric—it is a public loop. A public loop can contain up to 126 NL_ports
and one FL_port. If the fabric connects to another arbitrated loop, then an initiator
on one public loop might be able to communicate with a target on another. For
more about Fibre Channel fabric, see
34 SL500: Interface Reference Manual • July 2008
"Arbitrated Loop with Hub" on
"Direct Fabric Attachment" on page 38.
Revision: F • 96122