Optical Fiber Channel Protocol - Technopediasite

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Tuesday, June 19, 2018

Optical Fiber Channel Protocol

Posted By: technopediasite


Image result for image of network topology


Optical Fiber Channel is a protocol designed to meet the many requirements related to the increasing demand for high performance information transfer,It provide the more bandwidth.

The goals of Fibre Channel

Allowing manywell-known existing channel and networking protocols to run over the same physical interface and media.
High bandwidth (100Mbps and beyond).
Flexible topologies.
Connectivity over several kilometers
Support for multiple data rates, media types, and connectors.

In general, Fibre Channel attempts to combine the benefits of both channel and network technologies. There are two basic types of data communication between processors and between processors and peripherals: channels and networks.

A channel is a closed, direct, structured, and predictable mechanism for transmitting data between relatively few entities. Typically, once a channel is set up there is very little decision
making required, thus allowing for a high speed, hardware intensive environment. Channels are commonly used to connect peripheral devices such as a disk drives, printers, tape drives, etc.,to a workstation. Common channel protocols are Small Computer System Interface (SCSI) and High Performance Parallel Interface (HIPPI).

Networks are able to automatically adjust to changing environments and can support a larger number of connected nodes. These factors require that more decision making takes place in order to successfully route data from one point to another. Much of this decision making is done in software, making networks inherently slower than channels.

Examples of common networks are Ethernet, Token Ring, and Fiber Distributed Data Interface (FDDI).

Fiber Channel will most likely continue to expand into the storage markets, which will make use of its benefits over traditional channel technologies such as SCSI. Being able to access mass storage devices quicker and from greater distances is very attractive to such applications as multimedia, medical imaging, and scientific visualization. Because of the greater distances allowed, Fiber Channel has advantages in disaster recovery situations since storage devices can be placed remotely.

Unfortunately, the current trend in Fiber Channel is to continue to define more and more standard documents that increase the complexity of the protocol. This is probably the greatest threat to its future.

Fiber Channel Topologies

In Fiber Channel technology, the FC-0 layer describes the link between two ports. The link consists of a pair of optical fibers or electrical cables. Given that the FC-0 layer is designed for maximum flexibility, it allows for use of a wide variety of technologies to meet a range of system requirements.

The switch that connects the devices is called the Fabric. The link between two devices consists of two unidirectional fibers that transmit in opposite directions. Each fiber is attached to a transmitter of a node port (N_Port) at one end and a receiver of another
N_Port at the other end. This is the simplest topology, as shown in below figure.

Image result for image of Point to Point Topology
When Fabric is present in the configuration, a number of different ports may be connected. The fiber may attach to a N_Port and to a port of the Fabric (F_Port), as shown in below figure.

Image result for image of Fabric Topology

Moreover, the loop topology allows for multiple Ports to be connected together without a routing switch.

Image result for image of Loop Topology
The topology can be selected depending on the system performance requirements.



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