One embodiment of the disclosures made herein is a method of detecting a
transmission unit fault condition in a network system. In accordance with
such a method, an operation is performed for designating transmission
units received at a first counting location of a datapath, during a first
duration consisting of a first specified counting interval and a first
specified settling interval after the first specified counting interval
elapses, as first designated transmission units. An operation is
performed for determining a first datapath ingress transmission unit
count for the first designated transmission units at a first counting
location during the first duration. An operation is performed for
determining a first datapath ingress transmission unit count, an
operation is performed for determining a first datapath egress
transmission unit count for the first designated transmission units at a
second counting location of the datapath during the first duration. After
determining the first datapath ingress transmission unit count and the
first datapath egress transmission unit count, an operation is performed
for indicating a transmission unit fault condition associated with the
first specified counting interval when a difference is determined between
the first datapath ingress transmission unit count and the first datapath
egress transmission unit count after the first specified settling
interval elapses.