Over-subscription does not necessarily mean over-utilization
30MB/s 30MB/s All links are 200MB/s 30MB/s
Over-subscription = 3:1 Actual utilisation = 50%
50MB/s 50MB/s
Over-subscription does not necessarily mean over utilization:
The over-subscription ratio for an ISL is defined by the number of ports that could contend for that ISL.
Actual utilization depends on actual throughput.
In this example, the ISL over-subscription is 3:1 because 3 host ports are contending for a single ISL, but actual utilization is less than 50% of the 2Gb/s link because the aggregate throughput of the hosts is only 90MB/s.