including the group id is assembled and is advertised in the network in accordance with the routing protocol ospfte and isiste according to rfc4203 because a 64 bit area is determined as the area for the srlg a group id of up to eight characters may be stored if one character is 8 bits fig5 illustrates the processing in each network element when receiving advertisement information topology information if receiving topology information step 1000 first whether information set in advance to contain group ids or release ids i e srlg or admingroup is included is examined step 1002 if not included no a conventional normal operation such as recording of topology information is performed step 1004 if included yes the contents are confirmed step 1006 if the contents are not a release id step 1008 whether it matches the prefix of the tid assigned to its own network is examined step 1010 if the two match yes the advertisement source source is registered at the authorized side of the access authorization list step 1012 if they do not match no it is registered at the unauthorized side step 1014 thereby in each network element an access authorization list such as illustrated in the following table 4 and table 5 is created at step 1008 when the content of the srlg or admingroup is a release id the access authorization list is invalidated step 1016 and the contents of the access authorization list are deleted step 1018 thereby supervision and control over the management areas become possible and emergency maintenance of the entire network becomes possible in.