occurrences (cause 97) Invalid information element Signalling link counter counting for information element nonexistent or not implemented occurrences (cause 99) Invalid information Signalling link counter counting for invalid information element contents occurrences (cause 100) ERQ(establish request Signalling link counter counting for recovery on ERQ_timer expiry message)_tim expiry occurrences (cause 102) REL(release request Signalling link counter counting for recovery on REL_timer expiry message)_timer expiry occurrences (cause 102) RES(reset request Signalling link counter counting for recovery on RES_timer expiry message)_tin expiry occurrences (cause 102) BLO(block request Signalling link counter counting for recovery on BLO_timer expiry message)_timer expiry occurrences (cause 102) UBL(unblock request Signalling link counter counting for recovery on UBL_timer expiry message)_t timer expiry occurrences (cause 102) Unrecognised parameter Signalling link counter counting for message with unrecognised parameter, discarded occurrences (cause 110) OSAI allocation failure Signalling link counter counting for originating signalling association identifier (OSAI) allocation failures Channel unavailable Signalling link counter counting for requested AAL type 2 channel was not available in the destination AAL type 2 node occurrences Adjacent node unavailable Signalling link counter counting for connection establishment rejected since the signalling relation into the adjacent AAL type 2 node was not available Transmission Network Planning and Optimisation ATM Layer Performance A list of example ATM counters is shown in Table 3.19. The ATM KPIs could then be as follows, where the ingress cells can be estimated using the following formula: IngressCells 22 DiscardedCLP0Cells + DiscardedCLP1Cells + EPDCells + PPDCells + DiscardedPolicingCells + TransmittedCells + DiscardedChecksumErrorCells + DiscardedUTOPIAInterfaceCells + DiscardedCRCErrorCells + DiscardedErroredCells (3.78) The ingress lost cells can be estimated usin