Fibre Channel Layers

Pre-requisites: Fibre Channel, FCP (Fibre Channel Protocol)

Fibre Channel is a high-speed data transfer protocol providing in-order, lossless delivery of raw block data. Fibre Channel is primarily used to connect computer data storage to servers in storage area networks in commercial data centres. 

layers of Fibre Channel 

1. Fibre Channel FC-0 Overview : Fibre Channel (FC) is a high-speed data transfer technology used for storage area networks (SANs). FC-0 refers to the physical layer of the Fibre Channel architecture. A Fibre Channel cable Is typically an optical cable that transmits data between devices in a Fibre Channel network. The plug is the connector that attaches the cable to the device.

The signal encoding used In Fibre Channel is 8B/10B, a method that divides data into 8-bit symbols and adds 2 bits of overhead to each symbol for error detection and correction. This encoding allows Fibre Channel to transmit data at high speeds with low error rates.

2. Fibre Channel FC-1 Overview: Fibre Channel FC-1 refers to the data link layer of the Fibre Channel architecture. It is responsible for providing reliable data transfer by ensuring that data frames are transmitted without errors and in the correct order. FC-1 layer performs functions such as flow control, data link error detection and correction, and buffer-to-buffer flow control. It also provides data framing, which defines the format of the data frames transmitted over the Fibre Channel network. 

FC-1 layer provides the foundation for FC-2 (network) and FC-3 (transport) layers to build upon, and is essential for ensuring the efficient and reliable transfer of data in a Fibre Channel network. Overall, the FC-1 layer is crucial for maintaining the integrity and performance of a Fibre Channel network.

3. Fibre Channel FC-2 Overview: Fibre Channel FC-2 refers to the network layer of the Fibre Channel architecture. It is responsible for providing routing and switching of data frames between devices in a Fibre Channel network. The FC-2 layer performs functions such as address mapping, routing, and switching of data frames between devices. It uses unique device addresses to identify devices in the network and routes data frames to the correct destination. FC-2 layer also provides network-level flow control, which regulates the flow of data frames to prevent congestion in the network. This helps to ensure that data frames are transmitted efficiently and effectively in the Fibre Channel network. 

In summary, the FC-2 layer is responsible for the routing and switching of data frames in a Fibre Channel network, and provides the necessary functionality for interconnecting multiple devices and allowing them to communicate with each other.

4.Fibre Channel FC-3 Overview: FC-3 is the third level of the Fibre Channel protocol stack and is responsible for providing reliable, high-speed data transfer services to upper-layer protocols. FC-3 provides error detection, flow control, and data encapsulation functions, ensuring that data is transmitted reliably and efficiently between devices. FC-3 also supports various topologies, including point-to-point, arbitrated loop, and switched fabric, allowing for flexible and scalable SANs.

5.Fibre Channel FC-4 Overview: Fibre Channel FC-4 is the fourth layer of the Fibre Channel (FC) protocol stack. It provides a standard set of services, known as application protocols, to upper layer protocols such as SCSI (Small Computer System Interface) and IP (Internet Protocol). 

These services allow FC-4 to carry various data payloads, including block data, file data, and video data, over a Fibre Channel network. The goal of FC-4 is to provide a flexible, scalable, and high-performance data transport solution that supports a variety of storage and networking applications.