WAN Protocols

The Internet or Wide Area Network gained prominence in the recent past due to its ubiquitous nature of facilitating information sharing and business management across the globe. As any kind of activity is governed by a set of rules and standards, so is the functioning of this intricate WAN structure. WAN protocols are those protocols or technologies, which determine the efficient performance of WANs. These have a profound impact on business continuity, a key factor for Enterprises.

Technological appliances can function efficiently based on the features they support and the protocols governing the same. WANs (Wide Area Networks) use diverse networking equipment and technology. They differ from what is used by Local Area Networks (LANs). Most WAN protocols and technologies are layer 2 protocols (data link layer). The key WAN protocols that are in use are Asynchronous Transfer Mode (ATM), Broadband Access, Frame Relay, Point-to-Point Protocol (PPP), Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), X.25, and a few other WAN protocols. It is important to have a deeper understanding about these concepts as they are the links to enhancing applications over the Internet, and thereby power businesses in the competitive marketplace. The following is a brief outline of some of the more important protocols.

Asynchronous Transfer Mode

ATM is a packet switching protocol that enables encoding of data traffic into small predetermined sized cells. This protocol is based on connection-oriented technology. It operates by establishing between two end points, a virtual circuit even before exchange of data commences. The protocol suite of ATM sets up a mechanism to route traffic on a data stream that has fixed 53-byte packets. Switching and multiplexing are alleviated through using the fixed-sized cells. In order for communication to be established, two systems on the network are required to notify every intermediate switch regarding service demands and traffic parameters. As a cell relay protocol, ATM renders data link layer services, which run over layer 1 links. Comprising inherent properties of circuit switched as well as packet switched networks, ATM is well suited for WAN data networking and real-time media transport.

ATM supports diverse services through ATM Adaptation Layers (AALs). The AAL transmits the ATM cells between the ATM layer and a higher layer. It performs an operation called Segmentation and Reassembly (SAR), an important task. Data is segmented into ATM cells while information received from the higher layers is relayed. During the process, the AAL reassembles payloads in a format that can be understood by higher layers. ATM, as an essential WAN protocol, also plays its major role, that is, one of informing the network about the type of traffic to be transmitted and the traffic’s performance requirements. This concept is also interlinked to Quality of Service (Qos), a crucial service for uninterrupted and “always up” connectivity in businesses.

Broadband Access

Broadband or Broadband Internet Access refers to high speed Internet access, and is one of the most popular of WAN protocols due to its high data transmission rate. Broadband can yield speeds of 256 kbit/s or more. Digital Subscriber Line (DSL) and cable modems are the standard broadband technologies used in a majority of areas. Newer technologies that have evolved include Very High Bitrate DSL (VDSL or VHDSL) and fiber-optic cables. DSL is based on modem technology for Internet access over copper telephone lines. Multiple DSL users are connected to the high-speed network using a Digital Subscriber Line Access Multiplexer (DSLAM). The telephone company employs the DSLAM to effectuate aggregation of data transmission from available DSL lines and then interconnecting them to the ATM network. At the transmission end point, a DSLAM forwards data to a DSL connection after demultiplexing the signals.

The different types of DSL connections (ADSL, HDSL, SDSL, IDSL and VDSL), collectively referred to as xDSL, establish connectivity between the telephone company and office. Digital Subscriber Lines use several modulation technologies: Discrete Multitone Technology (DMT), Simple Line Code (SLC), Carrierless Amplitude Modulation (CAP), Multiple Virtual Line (MVL), and Discrete Wavelet Multitone (DWMT).

Integrated Services Digital Network (ISDN), the basic network system of early WAN protocols, provides digitized phone connectivity and enables high speed transmission of voice, data, video and graphics across standard communication lines at the same time through bearer channels. ISDN can be transmitted through packet switched networks, and other types of networks besides telephone networks. ISDN service comprises two basic types, namely basic Rate Interface (BRI) and Primary Rate Interface (PRI). While BRI contains a total 160 kb/s for use of individual users, PRI offers a total of 1536 kb/s and is designed for users who require more capacity, such as large Enterprises.

Frame Relay

Frame Relay, a WAN protocol based on packet switching technology, is exclusively for internetworking Local Area Networks (LANs), that is, transmission of data between LANs and WAN end points. A cost-efficient method, frame relay is widely used by network providers as an encapsulation method for voice and data, and used between LANs across a Wide Area Network. The user will have a private or leased line to a frame relay node. Frame relay works on the physical and data link layer, and facilitates information transfer from one user device to another over multiple switches and routers.

Advancements in other technology have resulted in a steady decline in usage level of frame relay technology. However, rural areas that are yet to experience technology such as DSL and cable modem, continue to use this cost-effective WAN protocol with continuous connectivity at 64 kb/s.

Point-to-Point Protocol

PPP is a data link protocol that is used to directly connect two nodes across serial cables, telephone line, trunk line, cellular phone, exclusive radio links, or fiber optic links. Point-to-point protocol is a WAN protocol widely used by customers for dial-up access to the Internet. This protocol helps to establish connection over synchronous and asynchronous circuits. Encapsulation is an important function of PPP wherein PPP frames, in order to provide framing and other routines such as detection of transmission errors, are encapsulated in a lower layer protocol. Point-to-Point Protocol over Ethernet (PPPoE) and Point-to-Point Protocol over ATM (PPPoA) are the two standard encapsulated PPP forms. They are employed to perform functions such as those executed by DSL services.


Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) are multiplexing WAN protocols, which enable transport of multi digital bit streams across the same optical fiber by using Light Emitting Diodes (LEDs) or lasers. SONET and SDH are closely related protocols that are based on circuit mode communication. SDH ascertains compatibility between optical-fiber based digital telephone links instead of copper cables. Deployed in a broad way, SONET/SDH enables various ISPs to share the same optical fiber simultaneously without interrupting each other’s traffic load. They are physical layer protocols, which offer continuous connections without involving packet mode communication, and are distinguished as time division multiplexing (TDM) protocols.


X.25 is packet-switched network based WAN protocol for WAN communications. It delineates data exchange and control of information within a user appliance, Data Terminal Equipment (DTE) and a network node, Data Circuit Terminating Equipment (DCE). X.25 comprises physical links such as packet-switching exchange (PSE) nodes for networking hardware, leased lines, and telephone or ISDN connections. Its unique functionality is its capacity to work effectively on any type of system that is connected to the network. X.25, although replaced by superior technology, continues to be in use. It utilizes a connection-oriented service that enables data packets to be transmitted in an orderly manner.

WAN solutions to address specific needs

Every business requires enhanced technology solutions to maintain its WAN infrastructure, which is the kernel of communication. Innovators in the technology business, offer a comprehensive suite of WAN solutions, which are custom made to strengthen the WAN infrastructure for enterprises. These technology products provide advanced features including dynamic load balancing of inbound and outbound data traffic, optimization, reliability, security and WAN acceleration, Quality of Service (QoS), data compression, VPN security, VPN encryption capabilities. The competitive business world finds these solutions indispensable for the stability of Wide Area Networks decide the achievement of their business continuity goals.