The FC architecture supports three basic interconnectivity options point to point , arbitrated loop ,and Fibre Channel switched fabric.
- Point-to-point is simplest FC configuration in which two devices are connected directly to each other.
- This configuration provides a dedicated connection for data transmission between nodes.
- The point-to-point configuration offers limited connectivity , because only two devices can communicate with each other at a given time.
- It can not be scaled to accommodate a large number of nodes.
- Standard DAS uses point-to-point connectivity.
Fig. point to point connectivity
FIBRE CHANNEL ARBITRATED LOOP
- In FC-AL configuration devices are attached to a shared loop.
- FC-AL has a characteristics of a token ring topology and a physical star topology.
- In FC-AL each device contents with other devices to perform I/O operations.
- Devices on the loop must “arbitrated” to gain control of the loop. At any given time , only one device can perform I/O operations on the loop.
- The FC-AL implementation may also use hubs whereby the arbitrated loop is physically connected in a star topology.