Patent ID: 7596085

Claim:
An access network system comprising: a plurality of external network relay devices, which are relay devices for connecting to other networks; and a plurality of internal network relay devices for relaying information that is transmitted and received within the same network and that belong to any of a plurality of groups that are set to correspond to said external network relay devices; wherein each said external network relay device comprises: a group movement parameter measurement unit for measuring group movement parameters that are used for determining whether the need exists to change the group affiliation of said internal network relay devices; and a group control unit for, when measurement results of said group movement parameter measurement unit meet conditions that have been set in advance, transmitting group movement notification messages instructing the change of groups to internal network relay devices of its own group and causing the internal network relay devices to change to other groups; wherein: said internal network relay devices each comprise a group affiliation control unit for determining that its own device is a border relay device when at least one adjacent internal network relay device or external network relay device belongs to another group, and for notifying the results of this determination to the external network relay device of the group to which said internal network relay device belongs; and said external network relay devices each use said group control unit to designate as relay devices that are the objects of movement, which are the objects of movement to other groups, border relay devices of the border relay devices within its own group that lack a border relay device downstream and internal network relay devices that are connected downstream of the border relay devices; and notify each of internal network relay devices within its own group whether these internal network relay devices are said relay devices that are objects of movement.