Network Design – 101 Computing

LAN & WAN

Network Topologies

Network Components

Client Server Networks

VPN

Design Your Own Network

LAN vs WAN

A LAN (Local Area Network) is a network located on one site, where all the computers are geographically close to each others.

is a network located on one site, where all the computers are geographically close to each others.

A WAN (Wide Area Network) is a network that is spread across multiple sites sometimes geographically remote to one another. A WAN consists of several LANs connected together, often using third party equipment and cables. (e.g. BT lines in the UK or AT&T lines in the US)

The Internet is an example of WAN (the largest of all WANs!).

A router is needed to connect a LAN to a WAN (or to the Internet).

Star Topology

A network topology defines the layout of a network. It describes how different components/nodes of a network are connected together. One of the most frequent topology used in a LAN is the star topology where all computers and other devices are all connected to a central node: either a hub or a switch.Both a hub or a switch have the same purposes: to connect multiple computers or devices in a star topology. A hub is not as efficient as a switch and would often have less ethernet ports (e.g. typically 4 or 8 ports)A switch being more efficient than a hub could have a larger number of devices connected (e.g. up to 28 Ethernet ports).

Switch-Star Topology

To build a larger network, it is possible to combine multiple star networks using a central switch. This create a “switch-star” topology:

Other Topologies

Note that there are other types of topologies which are not based on the star topology. (e.g. bus topology, ring topology, full and partial mesh topologies).

A network topology defines the. It describes how different components/nodes of a network are connected together. One of the most frequent topology used in a LAN is thewhere all computers and other devices are: either aor aBoth a hub or a switch have the same purposes: to connect multiple computers or devices in a star topology. A hub is not as efficient as a switch and would often have less ethernet ports (e.g. typically 4 or 8 ports)A switch being more efficient than a hub could have a larger number of devices connected (e.g. up to 28 Ethernet ports).To build a larger network, it is possible to combine multiple star networks using a. This create aNote that there are other types of topologies which are not based on the star topology. (e.g. bus topology, ring topology, full and partial mesh topologies).

However, for now, we will focus on star based topologies as these are the most frequently used topologies to build a LAN for a school or a small business.

Network Components (Hardware)

At this stage, we have already looked at three of the main types of network components: router, hub and switch. Other devices can also be used on a network such as a Wireless Access Point (WAP) and a Firewall.

Router

At this stage, we have already looked at three of the main types of network components: router, hub and switch. Other devices can also be used on a network such as a Wireless Access Point (WAP) and a Firewall.

A router is needed to connect a LAN to a WAN (or to the Internet). A router scans data packets and redirects them towards the LAN or towards other routers depending on their origin and their destination.

Switches and Hubs

A switch is a network component used to connect multiple devices together in a star topology. A switch would have a number of Ethernet ports (typically between 8 and 28 ports) to connect to other devices such as workstations and servers, WAPs, other hubs or switches or to a firewall or a router.
A switch is more efficient than a hub as it can redirect traffic towards the device it is aimed at. Switches can hence be used on larger networks where hubs would be inefficient. (e.g. school network, hospital network, etc).

is a network component used to connect multiple devices together in a star topology. A switch would have a number of Ethernet ports (typically between 8 and 28 ports) to connect to other devices such as workstations and servers, WAPs, other hubs or switches or to a firewall or a router.A switch is more efficient than a hub as it can redirect traffic towards the device it is aimed at. Switches can hence be used on larger networks where hubs would be inefficient. (e.g. school network, hospital network, etc).

A hub is a network component used to connect multiple devices together in a star topology. A hub would have a number of Ethernet ports (typically between 5 and 8 ports) to connect to other devices such as workstations and servers, WAPs, other hubs or switches or to a firewall or a router.
A hub is not as efficient as a switch and hence should only be used on a small network. (e.g. home network).

Wireless Access Point (WAP)

A Wireless Access Point (WAP) is a network component used to connect multiple devices together without using wires. A WAP could hence be described as being a wireless hub! It provides WiFi access to a network.

Most WAPs have a fairly small coverage area (10 to 30 meters) hence several WAPs may be required to cover a large building.

Devices equipped with a wireless Network Interface Card (NIC) can connect to a WAP.

Wireless data can easily be intercepted by potential hackers hence the need to encrypt wireless transmissions and to set a network key to restrict access to a wireless network (WiFi).

Firewall

A firewall is a network component that usually “sits” just after the main router. It scans all incoming traffic to identify/block and report potential security threats coming from “outside” (e.g. the Internet) before they can reach the rest of the Local Area Network. A firewall is a necessary precaution to minimise the risk of hackers illegally accessing a network.

NIC Cards

To connect a workstation to a LAN, the workstation needs to be equipped with a Network Interface Card (NIC). The NIC card will have a wired connection (e.g. Ethernet port) and/or a wireless connection to connect wirelessly to a WAP (Wireless Access Point).

Ethernet Cables

Networking cables are used to connect one network device to other network devices or to connect two or more computers to share printers, scanners etc.

The most widely used network cables are Ethernet Cables of different categories (Cat3, Cat5, Cat6, etc). These are fairly cheap, strong and can support a bandwidth of either 10 Mbps, 100 Mbps, 1000 Mbps (1 Gbps) or even 10Gbps.

Other types of cables that can be used on a network include coaxial cables (10 Mbps) and optic fibre cables (10 Gbps).

Did you know?

On a home network, a router is often an “all in one” device which includes a router, a hub or a switch, a Wireless Access Point (WAP) and a firewall, all in one box called router (or home hub).

• Peer-to-peer networks
• Client-server networks

Peer-to-peer networks

A computer on a network is called a workstation. Two types of network can be setup.

In a peer-to-peer network, all computers are sharing files and other resources between each other without the use of a central server. This makes it easy to setup the network as there is no need to acquire and setup expensive servers. However, this can be difficult to manage as maintenance and computer upgrades (including security patches, virus protection) have to be performed on each single computer instead of being done centrally. This is the main reason why peer-to-peer networks are considered as less secure than client-server networks.

Client-Server networks

In a client-server network, end-users access the network by logging on a client computer/workstation. Other computers called servers (often with higher specifications) are also connected to the network and provide a dedicated and centralised service to all the workstations. There are different types of servers as described below. On a small network, a single server can have multiple purposes (e.g. web server and e-mail server or a proxy and a cache server)

File server

A server with large storage capacity used to store all the files from all the network users as well as from shared network areas.

E-Mail server

A server that manages all e-mail accounts and transfers (sending/receiving) of e-mails for all network users.

Backup server

A server with large storage capacity used to store backups (copies) of files and data from other servers/workstations. Should the live data be corrupted or deleted, backed up data can be recovered from the backup server.

Print server

A server that manage all print requests from network users, manage print queues and end-user print credits.

Application server

A server that has all the applications and software upgrades files so that they can be centrally managed and centrally applied to all workstations that connect to the applications server to receive and install the latest upgrades when relevant. On occasion applications can also run directly from an application server, reducing the need to install these on each workstation of the network.

Multimedia server

A server with large storage capacity used to store all multimedia content (video clips, audio files, etc.).

Web server

A server used to host a website or internal webpages. The server contains all the necessary files (web pages, graphics, etc.) and processes all web requests from web users.

Cache server

A server that temporary stores recently accessed data/files so that they can be retrieved from the cache server at a faster rate.

Proxy server

A proxy server functions as an intermediary between a client and a server.

It can be used to monitor access to the Internet and apply necessary restrictions and filters to allow or block access to specific websites (e.g. educational filters).

DNS server

A server on the Internet used to lookup domain names to retrieve their matching IP addresses. These are necessary as end-users prefer to type web addresses or e-mail addresses using domain names such as www.101computing.net as these are easier to remember than IP addresses. The domain name servers will convert/lookup such domain names to find their matching IP addresses needed to connect to the relevant servers.

access its network remotely (e.g. for employees working from home or on a business trip).

On occasions, a company may need its employees to(e.g. for employees working from home or on a business trip).

To do so, employees will connect to the company LAN using their own Internet connection. They will then authenticate to access to the company network as if they were on site and hence have access to the company’s private network.

To enable remote access to its network via the Internet, which is a public network, the company has to set up and configure a VPN (Virtual Private Network). This will also mean that all the communications between the remote user and the company network will have to be encrypted and the remote users will have to authenticate (e.g. enter their username and password) to gain access to the VPN, so that only authorised users can do so.

Design Your Own Network

Use our

Use our network designer tool to create the layout of the network used in your school/organisation: