Wide-area networks (WANs) are used for different LANs together. It can connect different LAN within the city, country, or global region. Different technologies are used for WANs and LANs. Generally, the ISPs provide WANs routers and switches to accommodate different services. As a network administrator, it is your responsibility to research possible network devices for purchase and use over the WANs.
The WANs operates ahead of the geographic scope and used to interconnect the enterprise LAN to remote LANs. The WAN is owned by service providers. The organization must pay a service fee and rent to use the services to connect the remote sites. The service provider also provides telephone network, cable services and satellite communication. The service provider also provides data transportation service, voice and video.
Regional or branch offices of an organization required to communicate and share data with the central site, which is not possible without the WAN. The organization also shares information with other customer using WAN. Employees of the organization who travel on company business frequently need to access information that resides on their corporate networks.
Home computer users also required to sending and receiving data across increasingly larger distances for example users communicate using the internet with banks, stores and variety of services. Students’ also accessing library indexes over the world.
WANs in the OSI Model
WAN operate the physical layer and data link layer of the OSI model. WAN access describes both physical layer delivery methods and data link layer requirements, including physical addressing, flow control, and encapsulation.
Physical Layer protocols express how to provide connections. It defines the electrical, mechanical and operational connection. Datalink layer protocols define data encapsulation before transmitting, and the mechanisms for transmitting the encapsulated data. Different technologies are used for this purpose, for example, Point-to-Point Protocol (PPP), Frame Relay, HDLC, Ethernet WANs, MPLS, VSAT and Broadband. Most of link uses point-to-point technologies.
Common WAN Terminology
The corporate and big organization required WAN connectivity for Internet connectivity including the connectivity of different locations of an organization to each other, for external services and for remote management. The organizations subscribed the WAN services and they pay for these services. The physical layer describes the physical connections between the company and the service provider network. The common terminology used in WAN are the following:
Customer Premises Equipment (CPE)
The devices located on the enterprise edge connecting to a carrier link including the wiring are known as Customer Premises Equipment (CPE). The company or enterprise can own or lease the CPE from service providers.
Data Communications Equipment (DCE)
Data communications equipment (DCE) also known as data circuit-terminating equipment, the Data communications equipment (DCE) consists of devices that establish, maintain and terminate communication network sessions between a Wide Area Network cloud and its destination. The modem is the example of DCE equipment because the modem is connected to your computer can receive data from your computer and send it over the LAN to another computer.
Data Terminal Equipment (DTE)
Data Terminal Equipment (DTE) can be a destination or source for digital data. DTE need DCE to carry out the data and connects to the local loop to the Wide Area Network cloud. DTE is capable of converting information to signals and also reconverting received signals to information. Common examples of data terminal equipment (DTE) are personal computers, printers, routers, servers etc.
A border between customer equipment and service provider equipment is called the demarcation point. This is the junction box located in the customer site that connects the Customer Premises Equipment (CPE) wiring to the local loop.
This is the copper cable or maybe the fiber cable that connects the Customer Premises Equipment (CPE) to the Local Central Office (CO) of the service provider.
Central Office (CO)
The Central Office is the service provider local office that connects the Customer Premises Equipment (CPE) to the provider network.
All equipment inside the Wide Area Network including, fiber-optic communications lines, switches, routers, and other equipment are Toll network.