Q-Logic 16-Feb User Manual

Page of 196
3 – Planning
Multiple Chassis Fabrics
59021-06 A
3-3
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3.2.2
Common Topologies
The SANbox2-16 switch supports three commonly used fabric topologies:
„
Cascade
„
Mesh
„
Multistage®
3.2.2.1
Cascade Topology
A cascade topology describes a fabric in which the switches are connected in 
series. If you connect the last switch back to the first switch, you create a 
cascade-with-a-loop topology as shown in 
. 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.
 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 sequential structure, that 
bandwidth will be shared by traffic between devices on other chassis.
„
Latency between any two ports is no more than three chassis hops.
„
48 Fibre Channel ports are available for devices.
Figure 3-1.  Cascade-with-a-Loop Topology