Control signal processor and communication system

Abstract

The invention reduces an overhead operation required for re-establishment of a physical signal link. A physical signal link (layer link) is switched over keeping a layer link in the OSI reference model. A database stores information indicating physical signal links and information indicating the maximum length of a layer frame determined according to the ability of physical signal links. When a physical signal link is to be switched over, a target physical signal link is selected and a physical signal link used by the link is switched to the target physical link without releasing the single layer link. The maximum length corresponding to the target physical signal link is obtained from the database , and layer frames having the maximum length are transmitted. Switching over a physical signal link is performed in the following manner. When a physical signal link switching-over request is given, establishment of a target physical signal link is required without releasing a layer link, and a multi-reception of control signals using both of the target physical signal link and an original physical signal link is started. After confirming establishment of the target physical signal link, a physical signal link used for transmitting a control signal is switched to the target physical signal link and release of the original physical signal link is required. After confirming release of the original physical signal link, a physical signal link for receiving a control signal is switched to the target physical signal link.