A solution for dividing an internal gateway protocol (IGP) domain in a network. The network comprises an access-side link and a non-access-side link. The access-side link comprises a link between access-side devices as well as a link between an access-side device and an aggregation-side device. The non-access side link comprises links other than the access-side link in the network. In the present solution, a network device determines a changed access-side sub-graph according to a change in a network topology of the network, and divides the IGP domain according to a link in the changed access-side sub-graph, wherein the access-side sub-graph is one or more connectivity graphs formed after removing non-access-side links in the network topology. The present solution can improve the efficiency of IGP domain division.