Q-Logic 8C Switch User Manual


 
3 Planning
Multiple Chassis Fabrics
59042-01 A 3-3
3.2.2
Common Topologies
This section describes three commonly used topologies:
Cascade
Mesh
Multistage®
3.2.2.1
Cascade Topology
A cascade topology describes a fabric in which the switches are connected in a
line. If you connect the last switch back to the first switch, you create a
cascade-with-a-loop topology as shown in Figure 3-1. The loop reduces latency
because any switch can route traffic in the shortest direction to any switch in the
loop. The loop also provides failover should a switch fail.
The cascade fabric shown in Figure 3-1 has the following characteristics:
Each chassis link contributes up to 200 MB/s of bandwidth between chassis,
400 MB/s in full duplex. However, because of the structure of the cascade
topology, the bandwidth will be shared between devices on other chassis.
Latency between any two ports is no more than three chassis hops.
24 Fibre Channel ports are available for devices.
Figure 3-1. Cascade-with-a-Loop Topology