I trying to understand SAN topology. If we have fabric and fabric mode with auto data rate is set == means we will get F_ports, right? And if we need use 8G link from SAN storage and no fibre mode is availible, does it OK to use p2p. And is so, it would be N_port. By brocade http://www.brocade.com/content/html/en/deployment-guide/brocade-vcs-storage-dp/GUID-48CF1FD9-DB97-494F-84C2-545F5027BD67.html i know that F_port using to connect N_port. Does any SAN switch using that logic? I cannot make changes to the switch, but can change node connection setting. And there is availible only FC-AL and P2P without auto datarate.
N-port is a node port, actually it's HBA on a server or a port on a storage array. It is used to connect a node to a Fibre Channel switch. On Brocade switch you would usually have F-port, which is "Fabric port" used to connect with node port. In rare situations you can get L- or FL- port on the switch when you have to deal with mostly deprecated FC-Loop topology. So do not specify FC-AL on your storage.
In your case set P2P on the storage and you will likely get normal F-port on the switch.
Point-2-point mode is the opposite of arbitrated-loop mode (AL). You usually do not want AL if there's a switch. Set all ports to P2P at all times unless you really do need AL mode (when you chain multiple devices on a single port).
In AL mode, ports pass on traffic to other ports behind them in the loop. At any time, there can only two ports active in a loop.