| This is an International Telecommunication Union Telecommunication Standardization Sector (ITU-T) standard that defines how connections between data terminal equipment (DTE) and data communications equipment (DCE) are maintained for remote terminal access and computer communications in public data networks (PDNs). X.25 specifies LAPB, a data link layer protocol, and packet level protocol (PLP), a network layer protocol. Frame Relay has, to some degree, superseded X.25. See also Frame Relay, LAPB, and PLP. |