How to Design a Network: Basics & Examples – Video & Lesson Transcript | Study.com

Multiple Local Area Networks Can be Connected to Form a Wide Area Network

Design Considerations For a Network

The first thing to be considered is understanding the requirements of the network. The network requirements of a small office linking together ten computers and related equipment are different from that of a large airline ticketing reservation system spanning across the world. The main factors to be considered are:

• The purpose of the network – exchange of information and data between computers, applications and database hosting, voice and messaging services
• The size of the network – number of users, area of coverage, location of the users, hardware, etc.
• The amount of data being transferred and exchanged
• The security of the data
• Other important factors to be considered – connectivity requirements (whether wired, wireless or combination), the type of cabling, the type of computers and equipment to be used and their locations, the software and operating systems to be used.

The approach used is similar to that of designing a highway system: the purpose and connected locations have to be identified, the total distance estimated, the amount of traffic and size of paths estimated, and the traffic management system explored.

Let’s explore further in the following sections.

Connectivity

Our diagram shows a WAN (Wide Area Network) containing two LANs (Local Area Network). WANs span large areas, while LANs are localized networks. A large WAN can contain many LANs. LANs are localized networks servicing a small area like a building or small campus, while a WAN covers much larger areas. The LAN is further divided into a wired and wireless network. A LAN can be constructed completely as a wired or wireless network, though in practice it has a combination of both. When a network is designed, the most important criteria is to decide if only a LAN or LAN/WAN combination is required.

If only a LAN is required, then it has to be decided if wired or wireless network (or a combination) is required. Wired networks give better transfer speed and more stable performance but are more costly. A wireless network is cheaper and must be constructed as part of the LAN if smartphone connectivity is required as all smartphones are wireless devices.

If a wired network is required, then the transmission media has to be decided. Cheaper copper cables are sufficient for network connections of a few hundred meters in locations with low electromagnetic interference. If the connections stretch beyond this limit, then fiber optic cable is mandatory; this cable is also mandatory if the connections have to pass through areas with high electromagnetic interference. For the WAN, which is required to link multiple LANs together, the choice of links and providers is important. A small WAN connecting LANs a few kilometers away from each other may use private or leased fiber for connectivity, while a large WAN connecting LANs located in many locations worldwide will probably have to subscribe to service provider networks to complete the WAN.

The design of the network must also consider the compatibility between the different components. All components communicate using predefined protocols, which are the network communications standard, and protocol compatibility is mandatory to ensure the network functions. For example, if the network connects to the internet, then the TCP/IP protocol must be supported by all components (including those on provider networks, if used).

Compatibility in the network also means that the various components must be sized correctly. The amount of data exchanged determines how busy the network is. For example, a network at a stock exchange during active trading hours will handle large volumes of data compared to a network supporting point-of-sale activities at a local neighborhood store.

The design of the network has to ensure that the network transfer rate can cater to the estimated network traffic with the expected response times and can cover the required physical reach. Typically, wired LANs can transfer data at 1Gbps (1 billion bits per second), wireless LANs at around 600Mbps (600 million bits per second), and WANs between 20Mbps to 100Mbps. The network design must take into consideration all these transfer rates and ensure smooth data flow without any congestion.

Other Design Considerations

Apart from the connectivity, the network design must also consider other factors like the software and operating systems, the computers and equipment to be used, as well as the redundancy and security requirements. The computers and equipment used must be compatible with the network and must have the adapters to connect to the network. The data transfer rate of the network must be comparable with the internal data transfer rate of the computers and other network equipment. For example, the highway interchanges must be able to handle traffic flow from the connected highways or lanes.

Similarly, the software and operating systems installed in the computers and other interconnected devices must also be compatible with the network. For security and redundancy purposes, the network design has to ensure that the desired features are supported. For example, whether intruder detection/prevention (like firewalls), data encapsulation and encryption, user and device authentication, and redundant networks and links are required. Finally, the placement of network components is also important. For example, in a WAN, the servers should be placed closest to LANs with the most number of users, and remote users can connect using remote desktop tools. Specialized equipment like bandwidth compressors can be installed at sites with high network traffic to compress data and improve performance.

Lesson Summary

All right, let’s take a moment or two to review. As we learned, there are many factors involved in the design of a computer network, which we defined as a collection of computers and other related equipment like printers, switches, access points, routers, and network storage devices connected together using physical wires and cables or by wireless means. The first step will always be to determine the purpose of the network and the expected performance.

After this, the network connectivity requirements can be analyzed and determined, which differ between WANs, which cover wide areas, and LANs, which cover localized areas. Finally, all other related factors should be considered in the network design. Though well designed initially, it has to be noted that networks have to be reconfigured from time to time as requirements or utilization patterns may change over time.