Explanation
Fibre Channel Architecture:-
➢ Connections in a SAN are accomplished using FC.
➢ Fibre Channel Protocol (FCP) is the implementation of serial SCSI-3 over an FC
network. In the FCP architecture, all external and remote storage devices attached to the
SAN appear as local devices to the host operating system.
➢ The key advantages of FCP are as follows:
➢ Sustained transmission bandwidth over long distances.
➢ Support for a larger number of addressable devices over a network.
➢ Theoretically, FC can support over 15 million device addresses on a network.
➢ Exhibits the characteristics of channel transport and provides speeds up to 8.5
Gb/s (8 GFC).
Fibre Channel Protocol Stack
➢ It is easier to understand a communication protocol by viewing it as a structure of
independent layers.
➢ FCP defines the communication protocol in five layers:FC-0 through FC-4 (except FC-3
layer, which is not implemented).
➢ In a layered communication model, the peer layers on each node talk to each other
through defined protocols.
➢ Fig 2.9 illustrates the fibre channel protocol stack.
➢ FC-4 Upper Layer Protocol
➢ FC-4 is the uppermost layer in the FCP stack.
➢ This layer defines the application interfaces and the way Upper Layer Protocols
(ULPs) are mapped to the lower FC layers.
➢ The FC standard defines several protocols that can operate on the FC-4 layer (see
Fig 2.9). Some of the protocols include SCSI, HIPPI Framing Protocol, Enterprise
Storage Connectivity (ESCON), ATM, and IP.
➢ FC-2 Transport Layer
➢ The FC-2 is the transport layer that contains the payload, addresses of the source
and destination ports, and link control information.
➢ The FC-2 layer provides Fibre Channel addressing, structure, and organization
of data (frames,sequences, and exchanges). It also defines fabric services,
classes of service,flow control, and routing.
➢ FC-1 Transmission Protocol
➢ This layer defines the transmission protocol that includes serial encoding and
decoding rules, special characters used, and error control.
➢ At the transmitter node, an 8-bit character is encoded into a 10-bit transmissions
character.
➢ This character is then transmitted to the receiver node.
➢ At the receiver node, the 10-bit character is passed to the FC-1 layer, which
decodes the 10-bit character into the original 8-bit character.
➢ FC-0 Physical Interface
➢ FC-0 is the lowest layer in the FCP stack.
➢ This layer defines the physical interface, media, and transmission of raw bits.
➢ The FC-0 specification includes cables, connectors, and optical and electrical
parameters for a variety of data rates.
➢ The FC transmission can use both electrical and optical media.