K.J., If I've got your question right, I think you may be correct. I been doing a little reading up:
"Nodes containing a single N_Port with a fiber pair link can be interconnected in one of three different topologies. Each topology supports bidirectional flow between source and destination N_Ports. The three basic topologies include:
Point-to-point: A single link between two N_Ports.
Fabric: More than two N_Ports can be interconnected using a 'fabric' which consists of a network of one or more 'switch elements.' A switch element contains two or more facilities for receiving and transmitting data under the protocol, termed 'F_Ports.'
"Arbitrated Loop: Multiple N_Ports [point to point] can also be connected together without the benefit of a fabric by attaching the incoming and outgoing fibers to different Ports to make a loop configuration. A Port which incorporates the small amount of extra function required for operation in this topology is termed an 'NL_Port.' This is a blocking topology - a single NL_Port arbitrates for access to the entire loop and prevents access by any other NL_Ports while it is communicating. However, it provides connectivity between multiple Ports while eliminating the expense of incorporating a switch element."
"In addition to F_Ports, which attach directly to N_Ports in a switched Fabric topology, several other types of Fabric Ports are defined. In a multi-layer network, switches are connected to other switches through 'E_Ports' (Expansion Ports), which may use standard media, interface, and signaling protocols or may use other implementation-dependent protocols." A Fabric Port that incorporates the extra Port states, operations, and Ordered Set recognition to allow it to connect to an Arbitrated Loop is termed an 'FL_Port'."
I wonder if the Arcxel "Stealth" loop mode is actually an NL_Port implementation that can't be called that since the switch claims a nonblocking architecture? They say it does "F_Port, FL_Port, 'Stealth' loop mode, E_Port."
The source is Alan F. Benner's "Fibre Channel - Gigabit communications and I/O for Computer Networks," McGraw-Hill (thanks George). I think a little bit of this book's knowledge makes me dangerous now <g>. Hope I haven't got it all wrong.
Douglas |
