Abstract: A VRRP fault detection method is applied to a VRRP group including one primary router and one or more secondary routers. The method includes: sending, by the primary router and the secondary router, link detection packets having an echo response function, where a destination address of the link detection packet is a virtual address of the VRRP group. The method also includes determining, by the primary router and the secondary router, whether response packets corresponding to the link detection packets sent by the primary router and the secondary router are received within a predetermined time, and if the primary router and/or the secondary router does not receive the response packet within the predetermined time, determining that the primary router is faulty.

Abstract: The present application relates to a method and an apparatus for switching between a master device and a backup device. The method for switching between a master device and a backup device includes: when an access device accesses a network by using the master device, detecting an interface that is on the master device and directly connected to the access device or a transmission device, so as to determine whether a link between the access device and the master device fails; and when it is determined that the link between the access device and the master device fails, instructing a redundancy group with a routing function to perform switching between the master device and the backup device, so that the access device accesses the network by using the backup device that is before the switching.

Abstract: A method for network device redundancy backup includes performing communication and exchanging a VRRP message directly between VRRP master and backup routers to negotiate a master and backup relationship and sending, by the VRRP master device using an interface connected to an access device, a gratuitous ARP packet to the access device, so as to instruct the access device to direct user traffic to the VRRP master router. According to this method, the VRRP master and backup routers communicate and exchange a VRRP message directly, and the VRRP master router sends a gratuitous ARP packet to an access device through an interface connected to the access device.