Embodiments of the present invention provide a method for activating a DSL. The method includes: sending, by a central office equipment, a sync frame period indication message to a customer premises equipment, where a sync frame period indicated by the sync frame period indication message is smaller than a specified sync frame period threshold; receiving a reply message sent by the customer premises equipment in response to the sync frame period indication message, where the reply message indicates whether the customer premises equipment accepts the sync frame period indicated by the sync frame period indication message; and if the reply message indicates that the customer premises equipment accepts the sync frame period, performing, by the central office equipment, vectoring training by using a corresponding sync frame within the sync frame period. The embodiments of the present invention further provide corresponding equipments, a system, and a program product.