An entry describes cumulative and aggregate MDI metrics for a
single traffic flow.
The devices creates a row in the cfmMdiMetricsTable when a flow
monitor starts monitoring a traffic flow and has been configured
to compute MDI metrics for the same traffic flow. Likewise, the
device destroys a row in the cfmMdiMetricsMetricsTable when the
corresponding flow monitor has ceased monitoring the traffic
flow (e.g., when a traffic flow has timed out).