What is Flogi, Plogi and Prli Logi?

In FC environment Flogi, Plogi and Prli Logi are one of the important concept. Due to this only the communication will happen in the FC environment. Will cover each one by one.

Table of Contents


  • It is known as Fabric login.
  • When ever a server/HBA turn on it send a flogi request to the locally attached FC switch.
  • After that switch will assign a 24 bit FCID
  • FCID is similar as IP address. IT helps to route traffic between switch and storage. Switch maintain a table of FCID to WWPN address Mapping.


  • After Flogi completes, initiator(Host) will send the Plogi to communicate with the Target(Storage system).
  • Based on the zoning configuration. Initiator will get the access.

Prli Logi

  • Once initiator connected to the Target. Now initiator will send a prli logi request also known as process logi.
  • Based on the LUN Masking storage system grants the access.


We already discuss about the Flogi, Plogi and Prli Logi there are few more topics that interview ask while questioning for the Flogi, Plogi and Prli Logi. Below are topics will discuss:

  • Domain Switch ID
    • Each switch in FC have unique domain ID it is similar as IP address
    • One switch in network act as a master switch and assign domain ID to other switch
    • Each Switch communicated based on domain id.
  • FCNS
    • FCNS is known as fiber channel name service.
    • FC switches share the Flogi database information with each other using the FCNS
    • Each switch in the network know about each target(WWPN) and how to each there.

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