CSA Group Information Technology - Fibre Channel - Part 122: Arbitrated Loop-2 (FC-AL-2) (Adopted ISO/IEC 14165-122:2005, first edition, 2005-06)

Scope This part of ISO/IEC 14165 specifies signaling interface enhancements for FC-PH, to allow L_Ports to operate with an Arbitrated Loop topology. This Standard defines L_Ports that retain the functionality of Ports as specified in FC-PH. The Arbitrated loop topology attaches multiple communicating points in a loop without requiring switches.  The Arbitrated Loop topology is a distributed topology where each L_Port includes the minimum necessary function to establish a Loop circuit. A single FL_Port connected to an Arbitrated Loop allows multiple NL_Ports to attach to a Fabric.  When an L_Port is operating on a Loop with at least one other L_Port, the L_Port uses the protocol extensions to FC-PH that are specified in this standard.  When an L_Port is connected with an N_Port or an F_Port, the L_Port communicates using the protocol defined in FC-PH.  Each L_Port may use a self-discovering procedure to find the correct operating mode without the need for external controls.