Device Login Process

Device Login process is a process when a new devices gets connected to a Fabric it gets registered with fabric so that it can communicate with other devices in the Fabric.

A device communicating in the fabric can be a Host server with Solaris, windows, Linux or a storage device. All kind of devices need to be registered with Switch for communicating with other devices.

Device Login process categorized in to 2 process a. FLOGI b. PLOGI

Below mentioned is the process explaining the Device Login process:

I have tried to categorize Device login in to steps. Now let’s look in to it.

FLOGI:

FLOGI is a process where a Device gets it Fabric address which is a 24 Bit address.

Step 1 (FLOGI)

FLOGI (Fabric Login) the first frame transmitted by an Node device that is attempting to attach to a switch.  The FLOGI contains many bits of information about this initializing end device (N_Port).

Step 2 (FLOGI ACC)

Switch will respond to the FLOGI with an FLOGI ACC.  The format of the FLOGI ACC is identical to the FLOGI request but the information contained within it will be specific to the responding switch/switch port and Fabric Identifier gets assigned to Node.

Step 3 (PLOGI Name Server):

Node port sends a PLOGI signal to Name server so that node is able to register with and send queries to the Name Server.

Step 4 (PLOGI ACC):

Switch will respond the node port request for port Login with Acknowledgement.

Step 5 (Register with the Name Server):

Once PLOGI gets acknowledged then Node port can register with Name server for discovery of Target storage devices or SAN Devices.

Step 6 (Name Server Accepts registrations):

Name server accepts the Node ports registration with Name server.

Step 7 (SCR – State Change Registration):

Node Port will request the switch Fabric controller to send it a Registered State Change Notification (RSCN) every time something in the fabric changes.

Step 8 (State Change Registration ACK):

Fabric controller will accepts the SCR notification request with the switch.

Step 9(Query Name server):

Query Name server for the list of devices Node port can contact with in a fabric.

Step 10(Name server response):

Name server will respond to the Node port request and it will send the list of devices it can contact.

In this Device login process we could see that Fabric services like Fabric Login, Name server and Fabric controller participate in device Login process.

Some services are used in Zoning, In my next post I will explain Zoning and Switch services used in Zoning.