Inlarge-scaleTCP/IP network, the autonomy which each organization possesses & uses the network whichis done.Internetwhenyou see in macro, has become the form which connects AS mutually.As for AS with the network which shares single path controlpolicy, the network which the individualInternetserviceprovider (ISP) and enterprise etc. possess &usehits to this. Inside being how large-scale, being complicated, when you see from outside, it is visibleas one network. As for AS NIC of eachcountry (network information center: It is identified in USJPNIC) and the likeby the ASnumber which issues.The protocol which is used in path controlinsideASthe protocol which is used in path control between IGP (Interior Gateway Protocol)and ASis called EGP (Exterior Gateway Protocol). In formerRIPandOSPF etc., BGP and the likeare usedon latter, path control, inside and outside AS is used becoming independent. As for this,the whole Internet is managed with the single path control system, scale being too large, efficient management to be difficult, in addition,network being modified on a largescale and/or obstacle occurring, because it is possible to stop influence inside AS.