In this paper, we designed, implemented, and evaluated the performance of software OpenFlow flow counters in a bare metal commodity switch. Normally, flow counters are implemented in hardware for line-rate operations and their number needs to be very large to support a large flow-based SDN network. Although these hardware counters operate very fast, they greatly increase the cost of an OpenFlow switch. In addition, due to the limited chip size of the switching ASIC used in an OpenFlow switch, the number of hardware counters cannot scale to a large number. To overcome these drawbacks, we designed and implemented software flow counters in a 48 port × 10 Gbps (port bandwidth) bare metal commodity switch and evaluated their performance and limitations. This paper also reports important findings obtained from this practical work.