Patent ID: 7054324

Claim:
An interface unit in a switch device, the switch device being one of a plurality of switch devices that are communicatively connected via a backplane, the interface unit comprising: a receiving unit configured to receive data frames from a communication channel on the backplane at predetermined intervals and generate interrupt signals in response to detected data changes that occur between consecutively received data frames, the backplane being used to distribute the data frames among the plurality of switch devices; a transferring unit configured to transfer the interrupt signals to a processing unit in the switch device for controlling protection switching in a corresponding network; a comparing unit configured to perform a bit-by-bit comparison between consecutively received data frames, the comparing unit being configured to generate an interrupt signal for the data signal if the bit-by-bit comparison determines an inequality between corresponding bits of the consecutively received data frames, wherein at least one of the consecutively received data frames, which is received prior to the other of the consecutively received data frames, is sent to the comparing unit; wherein the comparing unit is configured to generate an interrupt status signal for a particular received data frame as a result of the bit-by-bit comparison, the interrupt status signal including a unit status bit for each of the corresponding bits in the consecutively received data frames, and, if the bit-by-bit comparison determines an inequality between any of the corresponding bits in the consecutively received data frames, the interrupt signal is generated; wherein the switch device is a switch card communicatively connected to a plurality of other switch cards via the backplane, and the comparing unit is configured to perform the bit-by-bit comparison for consecutively received data frames from each of the other switch cards, thereby generating an interrupt status signal for each of the other switch cards; wherein the receiving unit further comprises a massive interrupt signal generator configured to receive the interrupt status signal generated for each of the other switch cards, and generate a massive interrupt signal based on the received interrupt status signals, the massive interrupt signal indicating whether an interrupt signal has been generated for any of the plurality of other switch cards based on the most recent bit-by-bit comparison for each of the other switch cards; and wherein the received data frames include switching event bytes and status bytes, and the generated interrupt signals are assembled into a memory map, which is used by the processing unit to navigate among a plurality of memory locations to find a particular one of the switching event bytes and status bytes giving rise to the massive interrupt signal.