Fibre Channel architecture

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Fibre Channel architecture provides various communication protocols on the storage system. The storage systems that are interconnected are referred to as nodes. Each node has one or more ports.

A storage system is a node in a Fibre Channel network. Each port on a storage system Fibre Channel host adapter is a Fibre Channel port. A host is also a node in a Fibre Channel network. Each port attaches to a serial-transmission medium that provides duplex communication with the node at the other end of the medium.

The storage system architecture supports the following basic interconnection topologies or network structures:
  • Point-to-point
  • Switched-fabric

Point-to-point topology

With point-to-point topology, also known as direct connect, you can interconnect ports directly. Figure 1 shows an illustration of a point-to-point topology configuration that includes one host system and one storage system.

Figure 1. Point-to-point topology example
This figure shows a host system that is directly connected to only one storage system.
Legend:
  •  1  is the host system.
  •  2  is the storage system.
The storage system supports direct point-to-point topology at the following maximum distances:
  • 16 Gb shortwave adapters have a maximum distance of 125 meters (410 ft).
  • 16 Gb longwave adapters have a maximum distance of 10 km (6.2 miles).
  • 32 Gb adapters have a maximum distance of 10 km (6.2 miles).
The maximum distances also vary depending on the cable type as shown in Table 1. There are three basic types of optical cable fiber. The orange cables are shortwave, multimode OM2 type cables. The aqua cables are multimode, laser-optimized OM3 and OM4 type. The yellow cables are longwave, single mode fiber. The connection speed in gigabits per second determines the distance that is allowed.
Table 1. Connection speed and distance by cable type
Cable type Speed Distance
OM2 16 Gbps 35 m (115 ft)
OM3 16 Gbps 100 m (328 ft)
OM4 16 Gbps 125 m (410 ft)
OM2 32 Gbps 20 m (65 ft)
OM3 32 Gbps 70 m (230 ft)
OM4 32 Gbps 100 m (328 ft)
The maximum distance for a longwave cable also varies depending on the speed and the type of optical transducer.

Switched-fabric topology

The switched-fabric topology provides the underlying structure that enables the interconnection of multiple nodes. The distance can be extended by thousands of miles by using routers and other storage area network components.

The storage system supports increased connectivity with the use of Fibre Channel (SCSI-FCP and FICON®) directors. Specific details on status, availability, and configuration options that are supported by the storage system are available at IBM® DS8000® series.

The storage system supports the switched-fabric topology with point-to-point protocol. You must configure the storage system Fibre Channel adapter to operate in point-to-point mode when you connect it to a fabric topology.

Figure 2 shows an illustration of a switched-fabric topology configuration that includes two host systems, two storage systems, and three switches.

Figure 2. Switched-fabric topology example
This figure shows two host systems and two storage systems that are connected to each other using three switches.
Legend:
  •  1  is the host system.
  •  2  is the storage system.
  •  3  is a switch.