NetBIOS Extended User Interface (NetBEUI) is a transport and network layer protocol developed to transport NetBIOS over local area networks. NetBEUI is non-routable. NetBEUI was an alternative to TCP/IP in early Windows networks.
References:
http://www.javvin.com/protocolNetBEUI.html
http://www.comptechdoc.org/independent/networking/guide/netnetbeui.html