Fibre Channel Ports
FL_Port Fabric Loop Port
FL_Port (Fabric Loop Port):
A port on a switch that connects to an arbitrated loop
Note that the hub does not contain any ports. Hubs do not contribute
“intelligence” to the loop.
The other option we have is a loop. Realistically loop is not used any more
outside of the storage systems. Disk drives still support only arbitrated loop.
So the internal architecture of our storage subsystems is still loop but
externally most of us now use switched fabric. But for backwards compatibility
a lot of devices still default to loop (for instance a lot of HBAs and storage
ports will try to join a loop when they first come up) so that means that our
switch can also support this, but if our switch sees that it is connected to a
loop or a device that is trying to talk to a loop it will issue a LIP (a Loop
Initialization Primitive). If it sees a LIP, the switch port becomes a FL (a Fabric
Loop Port). A Fabric Loop Port is a gateway.