光纤通道为上层协议（ULP）提供了通用数据传输工具，如智能外围接口（IPI）和小型计算机系统接口（SCSI）命令集、高性能并行接口（HIPPI）数据帧、IP（互联网协议）、ANSI/IEEE 802.2等。本国际标准FC-AL-2规定了对光纤通道物理和信令接口（FC-PH）的信令协议ISO/IEC 14165-111的增强，以支持两个或多个端口之间的通信，而无需使用结构拓扑。它定义了保留FC中指定的端口功能的L_端口- PH.仲裁环路拓扑在环路中连接多个通信点，无需开关；这是一种分布式拓扑结构，其中每个L_端口包含建立环路所需的最小功能。连接到仲裁环路的单个FL_端口允许多个NL_端口连接到结构。每个L_端口可以使用自发现程序来查找正确的操作模式，而无需外部控制。

Fibre Channel provides a general data transport vehicle for Upper Level Protocols (ULPs) such as Intelligent Peripheral Interface (IPI) and Small Computer System Interface (SCSI) command sets, the High-Performance Parallel Interface (HIPPI) data framing, IP (Internet Protocol), ANSI/IEEE 802.2, and others. This international standard, FC-AL-2, specifies an enhancement to the signaling protocol of the Fibre Channel Physical and Signalling Interface (FC-PH), ISO/IEC 14165-111, to support communication among two or more Ports without using the Fabric topology. It 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; it 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. Each L_Port may use a self-discovering procedure to find the correct operating mode without the need for external controls.