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Checking for high-network utilization on a switched network
There are several means for checking for high-network utilization on switched networks depending on the resources and tools you have on hand. In this tip I'll point at the general approaches and give an example of each.
- Device-based – review the packet traffic registered at the critical ports of a suspected switch or router, either manually or using a network management system. Determine over the periods of concern the coarse-grained flows and compare against the rated capacities. Depending on the technology used, it may also be able to calculate utilization levels based the packet counts at each devices and even project end-to-end utilization on certain paths.
HP's OpenView would be a high-end example and What's Up Gold would be a cheaper but effective alternative.
- Passive – "sniff" packets at a point on a critical path such as a firewall, router or switch. Determine over the periods of concern the coarse-grained flows and compare against the rated capacities. If the sniffing technology provides performance analysis capabilities, it may also be able to calculate projected utilization levels based on the behaviors of certain flows that it has detected. Certain passive approach technologies can be very effective at defining utilization relative a particular point on the network.
Sniffer would be an example of a point traffic measurement technology. It also supports a distributed view that is more end-to-end when multiple sniffer units
