F_Port Login

F_Port Login (FLOGI or fabric login) is used by a node port to determine if a fabric (Switch) is present and if so, exchange service parameters. Node ports must log into the fabric (Switch) before using the fabric. Following initial link or loop initialization and prior to communicating with other node ports, the adapter (by way of the device driver) performs a fabric login (FLOGI). This establishes a session between the node port (adapter) and fabric (switch). The fabric assigns the N_port its address when the FLOGI is accepted.

Timeouts: A timeout can indicate a problem in the:

The SAN (cable, GBIC, switch port settings).
To determine the problem, check the following:
- On the switch, check the state of the Port associated with the fibre channel adapter.
- On the switch, check stats for the Port associated with the fibre channel adapter. A high CRC count can indicate:
  1. Bad or loose cables
  2. A bad or loose GBIC on the switch
  3. A bad transmitter on the adapter

Failures
Generally you will get a reason for the failure. This reason should point to the problem area.

Check that the fibre channel link is up (Adapter LED's: Green - ON, Yellow - flashing)
On the switch, check the state of the Port associated with the fibre channel adapter

N_Port Login

N_Port_Login (PLOGI) is used to establish a session and exchange identities and service parameters between two node ports. The N_Port login is performed following the completion of the fabric login. If this login fails or times out, it usually indicates a problem out in the SAN. Check the following:

Timeouts
Timeouts can indicate a problem with a fabric port.

If a fabric (from the sense data the CC filed (RRRR RRRR EEEE EEEE TTCC)is 02), on the switch, check the state of the Port associated with the fibre channel adapter. If the fibre channel adapter is not logged (F_Port_Login (FLOGI) into the switch), then the N_Port_Login will time out.r.

Failures
Generally you will get a reason for the failure. This reason should point to the problem area.

Check that the fibre channel link is up (Adapter LED's: Green - ON, Yellow - flashing)
On the switch, check the state of the Port associated with the fibre channel adapter
Check the stats on the switch for any obvious problems with the link to the adapter and to the end device
Check the stats on the end device

N_Port Discovery

N_Port Discovery (PDISC) extended link service allows a node port to test the current login state and exchange service parameters with another node port without affecting the current login state or operating parameters between the two node ports. N_Port Discovery allows a node port (Adapter) to verify the identify of another node port (end device). It also allows the a node port to determine if another node port's service parameters have changed.

Timeouts
Timeouts can indicate a problem with a fabric port.

f the command times out, if a fabric (from the sense data the CC filed (RRRR RRRR EEEE EEEE TTCCis 02), on the switch, check the state of the Port associated with the fibre channel adapter. If the fibre channel adapter is not logged in(F_Port_Login (FLOGI)) to the switch, then the PDISC will time out

Failures
Generally you will get a reason for the failure. This reason should point to the problem area.

If the login state is "Not Logged in", the port receiving the PDISC responds with LS_RJT with a reason code of "Unable to supply requested data".
If the reason indicate no such device, it means the end device is not connected any longer.
If the reason is link down, It means the link for the adapter is down, make sure the cable is connected and the device and the end of the cable is on.

F_Port Discovery

F-Port Discovery (FDISC) Link service command allows and node to exchange the service parameters with the fabric (Switch) without affecting the current operating parameter or the fabric login state between the node port and the fabric.

If the node port is not logged-in with the fabric, the fabric port replies with F_RJT with reason code of " Login require"
If the the FDISC is received by a node port, the node port replies with LS_RJT with reason code of "Unable to supply requested data"
If the FDISC link service command timed out, on the switch, check the state of the Port associated with the fibre channel adapter.

Process Login

The process login (PRLI) is an option service used to establish and manage a session between two FC-4 processes. When a process login session is established, service parameters may be exchanged. SCSI Fibre Channel Protocol (FCP) mapping (an FC-4 protocol) requires a process login

Process Logout

Process logout (PRLO) provides a mechanism to terminate a login session between to ports

Logout

Logout (LOGO) is used to end the session between to node ports. It terminates all open Exchanges between the two ports

Fabric Address Notification

A Fabric Address Notification (FAN) allows a FL-Port (switch loop port) to provide information to public NL_Ports on an arbitrated loop following loop initialization.

If the topology is not arbitrated loop (AL) (check the CC field in the sense data) the device driver will log a message in the AIX error log.
The topology is determined when the link is brought up. Link initialization and topology discovery is a function of the device driver and the device at the other end of the cable.

Check that the switch supports FL_ports and allows AL topology
Check with the switch to determine why a FAN was sent by the switch when the topology was not AL

Extended link Service Commands