A. FC (Fibre Channel)

The National Commite for Information Technology Standart, standar that defines an ultra-high Speed, content independent, multilevel data transmission interfaces that support multiple protocol simultanously, fibre.
Channel support connectivity to million of devices over copper and/or fibre optic physical media and provide the best characteristic of both network and channel over driver topologies.

B. ESCON (Enterprise System Communication)
An IBM-Patented set of product and services that provide a dynamically connected environment, over fibre-optic cable, within mainframe or client server

ESCON (Enterprise Systems Connection) is a marketing name for a set of IBM and vendor products that interconnect S/390 computers with each other and with attached storage, locally attached workstations, and other devices using optical fiber technology and dynamically modifiable switches called ESCON Directors. In IBM mainframes, the local interconnection of hardware units is known as channel connection (and sometimes as local connection to distinguish it from remote or telecommunication connection). ESCON’s fiber optic cabling can extend this local-to-the-mainframe network up to 60 kilometers (37.3 miles) with chained Directors. The data rate on the link itself is up to 200 Mbps (million bits per second) and somewhat less when adapted to the channel interface. Vendor enhancements may provide additional distance and higher amounts of throughput.
ESCON, Fibre Channel, and Small Computer System Interface are three alternative technologies used in storage area networks (storage area network).

In the early 1990s, ESCON replaced a much slower and more cumbersome system of interconnecting mainframes and attached devices known as the bus-and-tag cable. Bus-and-tag cable was copper, used a parallel bit attachment, and is usually referred to as a parallel environment in comparing it to the ESCON environment, which uses serial bit-by-bit technology.

C. FICON (fibre Connection)
An S/390 and z-Series Computer Pheripheral Interface, the I/O interface use S/390 and z-Series FICON protocol (FC-FS and FC-SB-2) over a fibre channel serial interface that configures unit attached to a Ficon-Supported fibre channel communication Fabric.

FICON (for Fiber Connectivity) is a high-speed input/output (I/O) interface for mainframe computer connections to storage devices. As part of IBM’s S/390 server, FICON channels increase I/O capacity through the combination of a new architecture and faster physical link rates to make them up to eight times as efficient as ESCON (Enterprise System Connection), IBM’s previous fiber optic channel standard.

FICON is the Fibre Channel version of ESCON. Escon was the first fiber optic I/O channel technology developed by IBM for mainframe system and storage connectivity. Escon was limited to 17MB/sec bandwidth.

FICON channel features include:
1. A mapping layer based on the ANSI standard Fibre Channel-Physical and Signaling Interface (FC-PH), which specifies the signal, cabling, and transmission speeds
2. 100 Mbps bi-directional link rates at distances of up to twenty kilometers, compared to the 3Mbps rate of ESCON channels at distances of up to three kilometers.
3. More flexibility in terms of network layout, because of the greater distances
4. Compatibility with any installed channel types on any S/390 G5 server
5. Bridge feature, which enables support of existing ESCON control units
6. Requires only one channel address
7. Support for full-duplex data transfers, which enables simultaneous reading and writing of data over a single link
8. multiplexing, which enables small data transfers to be transmitted with larger ones, rather than having to wait until the larger transaction is finished