A method of detecting a transmission unit fault condition, comprising: performing a first datapath ingress transmission unit counting operation during a first duration consisting of a first specified counting interval and a first specified settling interval after the first specified counting interval elapses, at a first counter of a first transmission unit counter set in a datapath at an upstream counting location where ingress transmission units are received, wherein a first datapath ingress transmission unit count is determined; performing a first datapath egress transmission unit counting operation during the first duration at a first counter of a second transmission unit counter set in the datapath at an downstream counting location where egress transmission units are provided, wherein a first datapath egress transmission unit count is determined; wherein the first specified settling interval is dependent upon a propagation delay through the datapath between the first counter of the first transmission unit counter set and the first counter of the second transmission unit counter set, indicating a 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, initiating a second specified counting interval after the first specified counting interval elapses; performing a second datapath ingress transmission unit counting operation, of transmission units designated during the second specified counting interval, at a second counter of the first transmission unit counter set in the datapath, wherein a second datapath ingress transmission unit count is determined; performing a second datapath egress transmission unit counting operation, during a second duration consisting of the second specified counting interval and a second specified settling interval after the second specified counting interval elapses, at a second counter of the second transmission unit counter set in the datapath, wherein the second specified settling interval is dependent upon a propagation delay through the datapath between the second counter of the first transmission unit counter set and the second counter of the second transmission unit counter set, and wherein a second datapath egress transmission unit count is determined; and indicating a fault condition associated with the second specified counting interval when a difference is determined between the second datapath ingress transmission unit count and the second datapath egress transmission unit count after the second specified settling interval elapses. performing a first datapath ingress transmission unit counting operation during a first duration consisting of a first specified counting interval and a first specified settling interval after the first specified counting interval elapses, at a first counter of a first transmission unit counter set in a datapath at an upstream counting location where ingress transmission units are received, wherein a first datapath ingress transmission unit count is determined; performing a first datapath egress transmission unit counting operation during the first duration at a first counter of a second transmission unit counter set in the datapath at an downstream counting location where egress transmission units are provided, wherein a first datapath egress transmission unit count is determined; wherein the first specified settling interval is dependent upon a propagation delay through the datapath between the first counter of the first transmission unit counter set and the first counter of the second transmission unit counter set, indicating a 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, initiating a second specified counting interval after the first specified counting interval elapses; performing a second datapath ingress transmission unit counting operation, of transmission units designated during the second specified counting interval, at a second counter of the first transmission unit counter set in the datapath, wherein a second datapath ingress transmission unit count is determined; performing a second datapath egress transmission unit counting operation, during a second duration consisting of the second specified counting interval and a second specified settling interval after the second specified counting interval elapses, at a second counter of the second transmission unit counter set in the datapath, wherein the second specified settling interval is dependent upon a propagation delay through the datapath between the second counter of the first transmission unit counter set and the second counter of the second transmission unit counter set, and wherein a second datapath egress transmission unit count is determined; and indicating a fault condition associated with the second specified counting interval when a difference is determined between the second datapath ingress transmission unit count and the second datapath egress transmission unit count after the second specified settling interval elapses.