ork Optimisation Table 3.19 Example of ATM counters Description of counter Discarded errored cells Physical layer termination point counter counting for cells with more than one bit error. A count of the number of incoming ATM cells discarded due to a header error check (HEC) violation. HEC is used for checking and correcting an error in the ATM cell header. One bit errors are corrected. If there are more errors in the header it cannot be corrected but the cell is discarded Discarded CLPO cells Computer unit counter counting for the total cell loss priority (CLP) 0 cells over the threshold on ingress. This tells how many high priority cells buffer management has discarded. There is a discard threshold for CLPO cells. When the number of CLPO cells in the buffer reaches the CLPO threshold, incoming cells are discarded Discarded CLP1 cells Computer unit counter counting for the total cell loss priority 1 cells over threshold on ingress. This tells how many high priority cells buffer management has discarded. There is a discard threshold for CLP1 cells. When the number of CLP1 cells in the buffer reaches the CLP1 threshold, incoming cells are discarded EPD cells Computer unit counter counting for the total cells discarded due to early packet discard (EPD) on ingress. When congestion occurs and buffers are filling, EPD discards new packets arriving at a queue. All cells associated with a new packet are discarded. The remaining buffer space can then be used for ATM cells belonging to packets that have already entered the queue PPD cells Computer unit counter counting for the total cells discarded due to partial packet discard (PPD) on ingress. PPD discards all the cells associated with the packet discarded during buffer overflow Transmitted cells Computer unit counter counting for the total number of ingress cells transmitted to the switch fabric Discarded policing cells Computer unit counter counting for ingress cells discarded due to policing action. Policing discards the cells, which can affect the quality of servic