A Wide Area Network (WAN) is required to connect beyond the boundary of the LAN. A WAN is a telecommunications network that spans over a relatively large geographical area. A WAN operates beyond the geographic scope of a LAN.

WANs may be built by a variety of different types of organizations, as follows:

A private WAN is a connection that is dedicated to a single customer. This provides for the following:

Single-Carrier WAN Connection

A single-carrier connection is when an organization connects to only one service provider

Dual-Carrier WAN Connection

A dual-carrier connection provides redundancy and increases network availability

Network requirements of a company can change dramatically as the company grows over time. Distributing employees saves costs in many ways, but it puts increased demands on the network. Not only must a network meet the day-to-day operational needs of the business, but it must be able to adapt and grow as the company changes.

Modern WAN standards are defined and managed by a number of recognized authorities including the following:

Almost all network communications occur using a serial communication delivery. Serial communication transmits bits sequentially over a single channel. In contrast, parallel communications simultaneously transmit several bits using multiple wires.

A circuit-switched network establishes a dedicated circuit (or channel) between endpoints before the users can communicate. Specifically, circuit switching dynamically establishes a dedicated virtual connection through the service provider network before voice or data communication can start. For example, when a user makes a telephone call using a landline, the number called is used by the provider equipment to create a dedicated circuit from the caller to the called party.

During transmission over a circuit-switched network, all communication uses the same path. The entire fixed capacity allocated to the circuit is available for the duration of the connection, regardless of whether there is information to transmit or not.

n. In contrast to circuit-switching, packet-switching segments traffic data into packets that are routed over a shared network. Packet-switched networks do not require a circuit to be established, and they allow many pairs of nodes to communicate over the same channel.

Packet switching is much less expensive and more flexible than circuit switching. Although susceptible to delays (latency) and variability of delay (jitter), modern technology allows satisfactory transport of voice and video communications on these networks.

Common types of packet-switched WAN technologies are Ethernet WAN (Metro Ethernet), Multiprotocol Label Switching (MPLS), as well as legacy Frame Relay and legacy Asynchronous Transfer Mode (ATM).

SDH - Synchronous Digital Hierarchy (SDH) is a global standard for transporting data over fiber-optic cable.
SONET - Synchronous Optical Networking (SONET) is the North American standard that provides the same services as SDH.

SDH/SONET define how to transfer multiple data, voice, and video communications over optical fiber using lasers or light-emitting diodes (LEDs) over great distances. Both standards are used on the ring network topology that contains the redundant fiber paths that allow traffic to flow in both directions.

Dense Wavelength Division Multiplexing (DWDM) is a newer technology that increases the data-carrying capacity of SDH and SONET by simultaneously sending multiple streams of data (multiplexing) using different wavelengths of light, as shown in the figure.

Many municipalities, cities, and providers install fiber-optic cable to the user location. This is commonly referred to as Fiber to the x (FTTx) and includes the following:

Security risks are incurred when a teleworker or a remote office worker uses a broadband service to access the corporate WAN over the internet.