Wide Area Network (WAN), It’s Classification and Types
Wide Area Network, also called Wide Area Network or WAN (English acronym Wide Area Network ), are communication networks that connect equipment to run user programs (at the application level) in geographic areas, hundreds or even thousands of square kilometers (regions, countries, continents …).
Each of the terminal equipment is usually called a node or host. The communication subnet (or subnet) is the set of transmission lines and also routers (or routers ) that allow hosts to communicate with each other. Different subnets can remain combined, resulting in more extensive wide area networks, as on the Internet.
Most commonly, hosts connect to wide area networks through a local area network or LAN. Still, there may also be terminals that relate directly to a router, without the need to be integrated into any other type of network. When a host sends a sequence of data packets, each router stores them and waits for the transmission line that it considers optimal to be free to forward them to the next router, and so on until it reaches the destination.
Table of Contents
Constitution of a Wide Area Network
The network consists of ECDs ( Switching Computers ) interconnected by high speed leased channels (e.g., 56 kbit / s lines). Each ECD uses a liable protocol for correctly routing data and also providing support to end-user computers and terminals connected to them—the support function ETD (User Terminals / Computers). The provision function of the ETD is sometimes called PAD ( Packet Assembly Disassembly- package assembler/disassembler). For example, ETDs, the ECD is a device that separates them from the network. The network control center (CCR) is accountable for the effectiveness and also reliability of network operations.
Switching Lines Classification
Lines that require dialing a code to establish communication with the other end of the connection.
Communication lines that maintain a permanent connection between two or more points. These can be two or four wires.
Link two DTEs Multipoint Lines: Link three or more DTEs
Types of WAN Networks
Switched by Circuits
Networks in which a call must remain through, and when the connection remains established, users directly link through the different network segments.
Switched by Message
In this type of network, the switch is usually a computer responsible for accepting traffic from the computers and terminals connected to it. The computer examines the address that appears in the header of the message to the DTE that should receive it. This technology allows the information to remain recorded for later service. The user can delete, store, redirect, or reply to the message automatically.
In this type of network, user data remains broken down into smaller pieces. These fragments or packets are inserted into the protocol’s information and travel the network as independent entities.
There is the concept of multiplexing of channels and ports known as a virtual circuit or channel in these networks because the user appears to have a dedicated resource when he shares it with others. After all, what happens is that they attend to bursts of traffic from different users.
Called Datagrams, they go directly from free state to data transfer mode. These networks do not offer acknowledgments, flow control, or error recovery applicable to the entire network, although these functions do exist for each particular link. An example of this kind of network is the Internet.
Public Telephone Switching Network (PSTN)
This network stood initially designed for the use of voice and analog systems. It was switching to establish the connection after agreeing to have dialed a number that corresponds to the numerical identification of the destination point.
Wide Area Network Topologies
Without going into logical issues such as the characterization of the devices connected to a WAN or the addressing used, wide area networks can present different physical typologies, depending on how the routers and transmission lines of the subnet remain arranged :
Each node connects with the others through dedicated circuits, always available for communication between two points.
The nodes are communicated with each other by lines that form a ring so that a packet can reach its destination by at least two paths (one in each direction that the crew travels).
Network in Intersection of Rings
One or more nodes join two ring topologies.
There is a hierarchy of nodes in a tree to move from one branch to another contiguous one. The packets must pass through a higher-level node.
All nodes remain directly connected to the rest.
A central node serves as a link to communicate all the other subnet nodes with each other.
In most cases, the WAN topology is irregular, without a strict pattern that dominates, sometimes resulting from the union of subnets with different original topologies.