Abstract: An apparatus and method for replacing a CPU cooling system, for example, a fan, while a computer continues to operate has a mechanism for maintenance personnel to signal that cooling fan replacement is about to begin. In response to the signal, a control mechanism causes the CPU to shift into an operating mode in which heat generation is reduced. In some cases, a clock frequency of the affected CPU and/or a duty cycle at which the CPU operates is reduced. After the fan has been replaced the control mechanism returns the CPU to a normal operational mode, for example, by increasing the clock frequency or duty cycle to a normal level. During the fan replacement procedure, the CPU and its software continues to run at lower than normal performance.

Abstract: An apparatus and method for replacing a CPU cooling system, for example, a fan, while a computer continues to operate has a mechanism for maintenance personnel to signal that cooling fan replacement is about to begin. In response to the signal, a control mechanism causes the CPU to shift into an operating mode in which heat generation is reduced. In some cases, a clock frequency of the affected CPU and/or a duty cycle at which the CPU operates is reduced. After the fan has been replaced the control mechanism returns the CPU to a normal operational mode, for example, by increasing the clock frequency or duty cycle to a normal level. During the fan replacement procedure, the CPU and its software continues to run at lower than normal performance.

Abstract: A method for identifying faulty modules within telecommunication devices, such as ATM switches, involves generating and attaching verification codes, such as a CRC or checksum codes, to data packets at an upstream location determining the integrity of the verification codes at each of multiple downstream location within a telecommunication device; and signaling an error condition where a corrupted data packet has been detected. A verification code may be written to a field of a data packet which is not used while the packet is in transit through the telecommunication device.

Abstract: A method for identifying faulty modules within telecommunication devices, such as ATM switches, involves generating and attaching verification codes, such as CRC or checksum codes, to data packets, such as ATM cells, at an upstream location, determining the integrity of the verification codes at each of multiple downstream location within a telecommunication device; and signaling an error condition where a corrupted data packet has been detected. A verification code may be written to a filed of a data packet which is not used while the ATM cell is in transit through the telecommunication device, thereby identifying a faulty module device without adversely affecting throughput.

Abstract: Methods and devices for detecting cell loss in telecommunication devices, such as ATM switches, attach cell loss detection information to cells in cell streams passing through the telecommunications devices. The cell loss detection information can trigger counters at up stream and down stream locations thereby avoiding the problem of synchronizing counters and ensuring that all cells to be counted have been flushed through the telecommunications device. The cell loss detection information can include a sequence number in a sequence of n sequence numbers where n is not a power of 2. Preferably n=2P−1, where P is an integer. Such series of sequence numbers allow the detection of lost cells in bursts consisting of a number of lost cells which is a power of 2. The methods and apparatus of the invention permit detection of unintentionally dropped cells in a call without the need to tear down the call.

Abstract: A method for verifying the integrity of data payloads of ATM cells passing through a switching device involves computing a payload integrity verification code for the payload portion of an ATM cell. The payload integrity verification code may be generated according to any error detection or error correction scheme. Preferably, the payload integrity verification code is stored in a portion of the standard ATM cell header which is not used while the cell is passing through the switching device. Preferably the payload integrity verification code is stored in all, or a portion of, the virtual path identifier or virtual connection identifier fields. The invention allows for the immediate identification of cells having corrupted payload data. Different actions may be taken on the detection of errors in the ATM cell header and ATM cell payloads respectively.