What is meant by WAN?

A collection of networks and/or local area networks (LAN) which communicate with each other is called a wide area network (WAN). A telecommunication network is extended over the geographical area for the basic computer network purpose (by connecting all smaller networks). From any part of the world, WAN allows communication and sharing the data between devices.

Generally, wide area networks are built for a particular organization (are private). Internet connection for the organization LAN is built using WAN. Leased lines are also used to build WANs and frame relay service is used as an alternative to the point-to-point service. A leased-line is a connection between points, which is set up using telecommunication carriers. WAN can transfer images, video, data, and audio over distance.

Components of WAN

The important components of WAN are,

• Routers: A router is an electronic device that connects LAN to WAN. Routers handle the task of routing the messages between the networks.
• Switch: Switch is a network device that selects the circuit or path for sending the data to its destination.
• Modem: Modem is the short form of modulator/demodulator. It enables the computers to communicate using telephone lines. the signal will be converted from digital signal to analog and vice versa for receiving and transmission.

Fundamentals of WAN

Generally, layer 1 and layer 2 networking technology will fall under the two primary categories namely WAN and LAN. WAN and LAN match the OSI layers (1 and 2), as they have similarities such as transmission speed, cabling details, encoding, forward logic, etc. WAN and LAN have some differences like the distance between the nodes, network payment (depending on the business models), etc. The fundamentals of WAN are,

Leased-Line WANs

Leases-line WAN forwards the data between routers. The leased line WAN work is similar to the ethernet crossover cable, which connects routers with some distance limitations.

Position with routers and LANs

Most of the end-user devices in a small/home office network have a direct LAN connection. Most of the Personal Computer (PC) connect the switch using an ethernet Network Interface Card (NIC). Mostly 802.11 wireless LAN is used by the devices like tablets and phones, which supports only Wireless LAN. To connect LANs using a WAN, the internet use routers. The router at each site connects the LAN with the WAN.

Physical details

Using a full-duplex logic, the leased line service can deliver the bits in both directions with a predetermined speed. When there is a full-duplex crossover, the routers are linked using ethernet. To perform a full-duplex operation, a leased line uses two pairs of wires (one pair at each direction for sending data). While creating a long circuit or links, a leased line does not have a long cable to connect two sites. The telco installs a cable network with a special device for switching and creates a computer network.

Data-link details

Layer 1 service is provided by leased line. The leased line itself will not define any protocol for the data link layer used at the leased line. Many organization creates data-link protocols to use and control the leased line. Protocols of all data-link will perform a role to control the accurate data delivery over the physical link (for certain types). The popular protocols of the data link layer used by the leased lines are Point-to-Point Protocol (PPP) and High-Level Data Link Control (HDLC).

Ethernet as a WAN technology

At the beginning of ethernet existence, ethernet is appropriate only for LANs. Ethernet standards are improved by IEEE, which made ethernet a reasonable one for WAN technology. A router interface is used to connect the ethernet link. The ethernet(fiber) link moves from the customer building and connects to a nearby service provider(SP) location is known as point of presence (POP). Instead of a telco switch, an ethernet switch is used by the service provider. In the service provider network, the service providers can use any technology to develop a particular ethernet WAN service.

The Ethernet WAN services have two names,

• Ethernet emulation refers to a service act (like a single Ethernet link).
• Ethernet over MPLS (EoMPLS) refers to Multiprotocol Label Switching (MPLS). EoMPLS A technology used in the SP cloud. The EoMPLS services can be understood easily only when there is a single ethernet link for two routers. The service provided by EoMPLS is,
  • Point-to-point connection (between custom devices).
  • Behavior (fiber ethernet link between devices).

Internet access

Cable and digital subscriber lines (DSL) are the two technologies of wide-area networks used to get internet access. These two will not replace the leased lines (in all cases); however, they play a major role in creating a WAN connection (between the office or home and internet).

Internet as large WAN

Internet is called a great cultural phenomenon and it is a big Transmission Control Protocol/Internet Protocol (TCP/IP) network. Internet includes LANs as the internet spans the world and WAN links need to connect various sites. Every TCP/IP and home-based network are included on the internet, along with wireless devices and phones. Internet core (mode of the internet) exits as WANs and LANs operated and owned by the internet service provider (ISP). In the internet core, ISPs create a link mess between each other. However, it does not matter which ISP gets connected to a particular person or company.

Internet access links (WAN)

The Internet needs to use numerous WAN links. All the links will connect the home or enterprise to an ISP and these links are known as internet access links. In the beginning, businesses use, WAN as an internet access link, and home-based users use others. Currently, leased lines are used by businesses for connecting a router (at business) to a router (at ISP); however, internet access links are used by the consumers (users) using the cable and Digital subscriber line (DSL) technologies. These technologies make use of the installed cables whereas, DSL uses analog phone lines and cable internet use cable TV cable.

Features of WAN

• WAN interconnects multiple LAN.
• Large capacity.
• Used for data and voice for landline and mobile phone.
• WAN covers an area up to 10000 kms, as compared to LAN which covers the area between 10 and 1500 meters and MAN covers the area between 5 to 6 kms.

How WAN differs from LAN and MAN?

WAN covers over larger areas geographically like state, county, or continent. Whereas LAN connects the computer within the small and specified geographical area and MAN covers a larger area compared to LAN but smaller compared WAN. It costs more to set up a WAN compared to LAN and MAN. The design and maintenance of WAN is difficult than LAN and MAN.

Context and Applications

This topic is important for postgraduate and undergraduate courses, particularly for,

• Bachelors in Computer Science Engineering.
• Associate of Science in computer science.

Practice Problems

Question 1: What is WAN?

1. Wide Area Network
2. Wide Around Network
3. Wide Area Networks
4. None of the above

Answer: Option a is correct.

Explanation: A collection of other networks or local area networks (LAN) which can easily communicate with one another is known as a wide area network (WAN). The abbreviation of WAN is a wide area network.

Question 2:  ____  service is an alternative to point-to-point service.

1. Cisco-routers
2. Frame Relay
3. DCE cable
4. Telecommunication

Answer: Option b is correct.

Explanation: WANs are built for the organization, which is generally private and created with leased lines by using a point-to-point connection to the private sites. Frame relay service acts as an alternative to point-to-point service.

Question 3: The propagation delay of WAN is ___.

1. Long
2. Short
3. Moderate
4. All the above

Answer: Option a is correct.

Explanation: Compared to LAN and MAN, the propagation delay of the WAN is long. The propagation delay of LAN is short and MAN is moderate.

Question 4:  Which of the following is a disadvantage of WAN.

1. Computer network
2. Telephone network
3. Costly to setup
4. Time-division

Answer: Option c is correct.

Explanation: WAN covers the larger geographical area and the setup is very expensive. To set up a WAN requires purchasing routers, security solutions, and switches.

Question 5:  Select the service provided by EoMPLS.

1. Point-to-point connection
2. Packet switching
3. Circuit switching
4. Cabling

Answer: Option a is correct.

Explanation: EoMPLS provides the services like the point-to-point connection between customer devices and behavior as a fiber ethernet links two devices.