US Patent 6910149 Multi-device link aggregation

The invention relates to multi-device link aggregation (MDLA). A first MDLA device is connected to a second MDLA device by an MDLA internal link. Each of the interconnected first and second MDLA devices is connected to at least one common link aggregation (LAG) partner device by an aggregated link, respectively. Typically, the first and second MDLA devices exchange protocol data units (PDUs) to detect devices that are connected to both the first and second MDLA devices such that they are able to trick the detected devices into behaving as though the two MDLA devices are a single device. If one of the MDLA devices fails, traffic of the associated aggregated link to the failed MDLA device can be automatically forwarded by the other non-failed MDLA device.