In a network including equipment noncompliant to the topology management protocol, a message substitution response system executing substitution response to a message discovered or topology search message in lieu of the noncompliant equipment is provided. The substitution response module generation unit 22 generates a substitution response module which responds to Discover message and topology search message in lieu of each of LLTD noncompliant equipment for every LLTD noncompliant equipment. The network simulation module generation unit 23 generates a network simulation module for simulating message transmission on the home network. The substitution response functional unit 24 simulates message transmission between the home network and each of substitution response modules, and message transmission between each of substitution response modules by said network simulation module.