Double-network card hot backup redundancy method

The invention relates to a double-network card hot backup redundancy method which comprises the following steps: two network cards of each machine are respectively connected to two exchanges in a network topology; the two exchanges are subject to inter-cascade connection; a network card monitoring a program sends messages to the exchanges and accepts answers using the IP address of the working network card, if a plurality of continuous messages receive no answer after a certain time interval, the working network card or a network device is judged to have fault, the system sends out a warning signal, records warning state, and switches the IP address to a backup network card; and when the working network card returns to be normal, the original IP address is switched to the working network card. The method can realize automatic switching when a certain working network card or a network device or an exchange has fault; and can switch back when the working network card returns to be normal, the switching program automatically executes, and the method can alarm and record faults, which perfectly solves the problem of cross faults.