lost+found
A Fibre Channel Primer: Part 2
W. Curtis Preston
In November's column, I discussed a lot of the basics of Fibre Channel, including:
- Why Fibre Channel was developed
- Who makes up the Fibre Channel "industry"
- What is Fibre Channel?
- What are the different types of Fibre Channel ports?
- How are Fibre Channel devices addressed?
In this column, I will build on that information and explain the different
Fibre Channel architectures: point-to-point, fabric, and arbitrated loop. In
case you don't have access to last month's column, let's review some important
information.
There are three "basic" types of ports, the N_Port, the F_Port, and the E_Port.
As you add arbitrated loop capabilities to these basic ports they take on the
"combined" names of: NL_Port, FL_Port, and G_Port, which are the most common
types of ports. An NL_Port is a node (device/host) port with arbitrated loop
capabilities. An FL_Port is a fabric port on a switch with arbitrated loop capabilities.
A G_Port is a multi-purpose port on a switch that can do fabric, arbitrated
loop, or expansion to another switch.
Another term that will be used in this article is HBA, or Host Bus Adaptor.
This is the industry term for a Fibre Channel interface card that plugs into
a host, such as a PCI or SBUS card.
A unique, 64-bit address is assigned to each port, and is referred to as its
WorldWide Name (WWN). If a port connects to an arbitrated loop, it will also
be assigned a dynamic 8-bit address, referred to as its arbitrated loop physical
address, or AL_PA.
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