Before restarting an IS-IS protocol process, the first device sends an IIH packet with a RR flag set and a hold time field being a first predetermined value to a second device. The first predetermined value is greater than a normal value of a hold time kept in the second device for the first device, and the first device establishes an adjacency with the second device. After receiving an IIH packet with a RA flag replied by the second device, the first device restarts the IS-IS protocol process and starts to execute a GR process. The IIH packet with the RA flag set is replied by the second device after the second device updates the hold time kept in the second device for the first device according to the first predetermined value.