Patent ID: 7518988

Claim:
A ring switchover method in a network constituted of layer 2 switches connected in a ring shape, each layer 2 switch having a path control function and a failure detection function, said ring switchover method comprising: providing in each layer 2 switch an address learning table in which a Media Access Control (MAC) address and a corresponding port are stored; on detection of a link failure between mutually neighboring layer 2 switches, transmitting a failure notification from packet from each neighboring layer 2 switch; in a layer 2 switch having received the failure notification frame, recording a Media Access Control (MAC) address of said layer 2 switch into the failure notification frame, and transferring the failure notification frame to a neighboring layer 2 switch; wherein, when the network is separated into two network groups caused by a failure, with respect to a host address connected to an arbitrary layer 2 switch, updating path information in the address learning table in a layer 2 switch belonging to the other group than the group to which said layer 2 switch belongs, so that a packet transmission direction on the ring is shifted to a port side opposite to the direction having been used up to the present; and, wherein updating the path information in the address learning table is performed by exchanging address information related to system modification between the arbitrary layer 2 switch and the layer 2 switch belonging to the other group by use of a system switchover frame.