Patent ID: 7856559

Claim:
A node apparatus for packet communication to which an extension module for executing predetermined processing is connected and which forwards packet data to the extension module, the extension module comprising a memory for storing connectivity authentication data, and a module controller for transmitting the connectivity authentication data stored in the memory to the node apparatus for packet communication when the connectivity authentication data is requested from the node apparatus for packet communication, the node apparatus for packet communication comprising: a switching unit; a network interface module connected to the switching unit, the network interface module receiving packet data from and forwarding packet data to a network; and a module connectivity authentication interface connected to the switching unit, the module connectivity authentication interface including: a connectivity authentication unit for authenticating permission of connection of the extension module based on the connectivity authentication data received from the extension module; a connection controller for receiving packet data from the extension module when the connectivity authentication unit authenticates the permission of the connection; and a module monitor unit for detecting whether there is an abnormality of the extension module based on a difference between an amount of the packet data forwarded to the extension module by the node apparatus and an amount of the packet data received from the extension module and, upon detecting that there is an abnormality of the extension module, notifying the connectivity authentication unit of the abnormality, and wherein the connectivity authentication unit, upon being notified of the abnormality, instructs the connection controller to stop receiving packet data from the extension module.