Description A Wide Area Network (WAN) is a computer network covering multiple distance areas, which may spread across the entire world. WANs often connect multiple smaller networks, such as local area networks (LANs) or metro area networks (MANs). The world's most popular WAN is the Internet. Some segments of the Internet are also WANs in themselves. A wide area network may be privately owned or rented from a service provider, but the term usually connotes the inclusion of public (shared user) networks.
A virtual private network (VPN) riding on the public switched data network (PSDN) is often used by organizations for their private and secured communications. VPN uses encryption and other techniques to make it appear that the organisation has a dedicated network while making use of the shared infrastructure of the WAN.
WANs generally utilize different networking technologies and equipment than do LANs. Key technologies often found in WANs include SONET, Frame Relay, X.25, ATM, and PPP.
WAN technologies and protocols are mostly data link layer (layer 2) protocols which are defined by many organizations over time. The key organizations in this space are IETF for PPP, ITU-T for ATM, Frame Relay, ISO for X.25 and SONET.
Key Protocols The key WAN protocols are listed as follows:
| WAN | Wide Area Network |
|---|---|
| ATM | ATM: Asynchronous Transfer Mode Reference Model |
| ATM Layer | |
| AAL: ATM Adaptation Layer Type 0-5 reserved for variable bit rate video transfer. | |
| ATM UNI: ATM Signaling User-to-Network Interface | |
| LANE-NNI: LAN Emulation - Network to Network Interface | |
| LANE-UNI: LAN Emulation - User to Network Interface | |
| MPOA: Multi Protocol Over ATM | |
| PNNI: Private Network-to-Network Interface | |
| Q.2931: ATM Signalling User Interface | |
| SONET/SDH | Synchronous Optical Network and Synchronous Digital Hierarchy |
| EoS: Ethernet over SONET/SDH | |
| Broadband Access | DOCSIS: Data Over Cable Service Interface Specification |
| BISDN: Broadband Integrade Service Digital Network | |
| ISDN: Integrated Services Digital Network | |
| Q.931: ISDN network layer interface protocol | |
| LAPD: ISDN Link Access Protocol Channel D (Q.921) | |
| xDSL: Digital Subscriber Line Technologies (DSL, IDSL, ADSL, HDSL, SDSL, VDSL, G.Lite) | |
| PPP | PPP: Point-to-Point Protocols |
| BAP: PPP Bandwidth Allocation Protocol | |
| BACP: PPP Bandwidth Allocation Control Protocol | |
| BCP: PPP Bridging Control Protocol | |
| CHAP: Challenge Handshake Authentication Protocol | |
| EAP: PPP Extensible Authentication Protocol | |
| LCP: PPP Link Control Protocol | |
| MultiPPP: MultiLink PPP (MP) | |
| NCP: PPP Network Control Protocol | |
| PAP: Password Authentication Protocol | |
| PPPoE: PPP over Ethernet | |
| PPPoA: PPP over ATM AAL5 | |
| PoS: Packet Over SONET/SDH | |
| X.25 | HDLC: High Level Data Link Control protocol |
| LAPB: Link Access Procedure Balanced for x.25 | |
| X.25: ITU-T WAN communication protocol | |
| Frame Relay | Frame Relay: WAN protocol for internetworking at layer 2 |
| LAPF: Link Access Procedure/Protocol (ITU Q.922) | |
| Other | IBM SDLC: Synchronous Data Link Control protocol |
Related Protocols LAN, MAN, TCP/IP
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