IBM V7000 Introduction And Implementation Manual page 513

Physical and signaling layers
The physical and signaling layers include the three lowest layers: FC-0, FC-1,and FC-2:
Physical interface and media: FC-0
The lowest layer, FC-0, defines the physical link in the system, including the cabling,
connectors, and electrical parameters for the system at a wide range of data rates. This
level is designed for maximum flexibility, and allows the use of a large number of
technologies to match the needs of the configuration.
Transmission protocol: FC-1
The second layer, FC-1 provides the methods for adaptive 8B/10B encoding to bind the
maximum length of the code, maintain DC-balance, and provide word alignment. This
layer is used to integrate the data with the clock information required by serial
transmission technologies.
Framing and signaling protocol: FC-2
Reliable communications result from Fibre Channel's FC-2 framing and signaling protocol.
FC-2 specifies a data transport mechanism that is independent of upper layer protocols.
Upper layers
The upper layer includes two layers: FC-3 and FC-4.
Common services: FC-3
FC-3 defines functions that span multiple ports on a single-node or fabric. The following
functions are currently supported:
– Hunt Groups: A set of associated N_Ports attached to a single node. This set is
assigned an alias identifier that allows any frames containing the alias to be routed to
any available N_Port within the set. This decreases latency in waiting for an N_Port to
become available.
– Striping: Striping is used to multiply bandwidth, using multiple N_Ports in parallel to
transmit a single information unit across multiple links.
– Multicast: Multicast delivers a single transmission to multiple destination ports. This
includes the ability to broadcast to all nodes or a subset of nodes.
Upper layer protocol mapping (ULP): FC-4
The highest layer, FC-4, provides the application-specific protocols. Fibre Channel is
equally adept at transporting both network and channel information and allows both
protocol types to be concurrently transported over the same physical interface.
A channel protocol example is Fibre Channel Protocol (FCP). It is used to transfer SCSI
commands and data over Fibre Channel and is commonly used in FC SANs.
Chapter 11. SAN connections and configuration
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