Technical data

AL_PA
The Arbitrated Loop Physical Address (AL_PA) is
used to address nodes on the Fibre Channel loop.
When a node is ready to transmit data, it transmits
Fibre Channel primitive signals that include its
own identifying AL_PA.
Arbitrated Loop
A Fibre Channel topology in which frames are
routed around a loop set up by the links between
the nodes in the loop. All nodes in a loop share the
bandwidth, and bandwidth degrades slightly as
nodes and cables are added.
Frame All data is transferred in a packet of information
called a frame. A frame is limited to 2112 bytes. If
the information consists of more than 2112 bytes, it
is divided up into multiple frames.
Node
The source and destination of a frame. A node
may be a computer system, a redundant array of
independent disks (RAID) array controller, or a disk
device. Each node has a 64-bit unique node name
(worldwide name) that is built into the node when it
is manufactured.
N_Port
Each node must have at least one Fibre Channel
port from which to send or receive data. This node
port is called an N_Port. Each port is assigned a
64-bit unique port name (worldwide name) when it
is manufactured. An N_Port is connected directly
to another N_Port in a point-to-point topology. An
N_Port is connected to an F_Port in a fabric topology.
NL_Port
In an arbitrated loop topology, information is routed
around a loop. A node port that can operate on the
loop is called an NL_Port (node loop port). The
information is repeated by each NL_Port until it
reaches its destination. Each port has a 64-bit
unique port name (worldwide name) that is built
into the node when it is manufactured.
Fabric
A switch, or multiple interconnected switches,
that route frames between the originator node
(transmitter) and destination node (receiver).
Using Fibre Channel Storage 6–3