Network Types and Typologies

Bus topology

A single line of devices connected together by one shared network cable. Common in the days of early networking, before the Ethernet hub and switch, but uncommon today. Also referred to as a network segment because the network may be extended by adding more segments of cable, allowing more computers to connect to a shared network.

Star Topology

Aka hub-and-spoke network. Unlike the single straight line of the bus topology, the start network is comprised of a central network device, such as an Ethernet switch, connected to various network devices, such as servers, computers, and printers, by individual network cables. In contrast to other network topologies, where a network device such as a computer or printer is directly cabled to another adjacent device, in a star network, each device is only connected to the central switch. All device-to-device communication is sent through the switch at the center of the network and then forwarded by the switch to the proper destination. Today, star networks are the most common type of network found in LAN environments.

CAN

Campus Area Network. Provides networking of multiple LANs across a limited area, like a university campus or a group of buildings owned by a company. Each LAN would typically be constrained to a single building (or even just a part of a building), and the CAN would link them together in much the same way as a WAN (wide area network) does but in a smaller geographic area. The CAN typically connects LANs owned by a single company, university, government agency, etc.

What are some characteristics of a Bus topology?

Computers connect to the network by physically tapping into the network cable using special adapters. This allows the network cable to remain one continuous conduit while also allowing the computers to send and receive electrical signals on the cable. The ends of the cable mus be properly terminated. At both ends of the network cable, special electrical resistors called terminators must be attached to absorb stray electrical signals on the wire.

Ring Topology

Created to combat one of the more challenging aspects of the bus network: traffic collisions. The way a ring topology works is illustrated by sitting around a campfire with everyone talking at once. you have a stick in your hand, calling it the "talking token", and quiet everyone down and pass the token around the circle. Only the person holding the token will be allowed to speak, and everyone else will listen, and the token is passed when done. The token cannot be held for very long, everyone will get a chance to hold the token, even if they have nothing to say.

True or false: the network cable has to be in a circle format in a ring topology.

False. The network cable may run in a similar pattern of a bus network topology but with some important differences: the network cable is interrupted by each computer on the ring, and the

What happens if the terminators are removed in a Bus topology?

If these terminators are removed or if the network cable is accidentally cut, the electrical signals will not be properly absorbed and will bounce back along the wire, causing communication loss (signal reflection).

Client-Server

In a client-server network model, there is a distinct server and a distinct client. The server is the system that stores data and information. The client is the machine that needs access to the data. This is the traditional model of networking since the 1990s.

LAN

Local Area Network. Consists of computers connected within a limited area. Some examples of LANs are a home, lab, or office building. Most often, LANs use Ethernet, WiFi, or both to connect to the network devices.

MAN

Metropolitan Area Network. Provides networking across a larger area than a CAN, but smaller than a WAN, such as a whole city or the equivalent of a metropolitan area (hence the name), though it is not necessarily limited by city boundaries. A MAN is made up of many LANs and is owned by many organizations, government entities, etc, within the city to create a fabric of network coverage, often at higher speeds than maybe commercially viable when connecting directly to a WAN when connecting to other entities in the same MAN.

Mesh topology

Often drawn as a web of direct connections between computers or nodes in a network. However, those connections may be permanent or constructed dynamically, as nodes need to talk to other nodes. A mesh topology permits nodes to communicate with each other; the topology may be either a full mesh, where very node has access to all other nodes, or a partial mesh network, where each node is only able to connect to a subset of the other nodes.

PAN

Personal Area Network. A network that is centered around a person and their devices. a PAN allows for various devices, such as a person's desktop computer, laptop, smartphone, tablet, headphones, wireless keyboard and mouse, etc, to communicate with each other, often over Bluetooth or USB.

Unlike other topologies, such as bus, ring, or star, mesh topologies are not necessarily constructed using __________

Physical network cables. The nodes may be connected using Wi-Fi or radio signals or by virtual links such as virtual private networks (VPNs). Another example of a mesh network is a collection of routers that are able to communicate with each other and learn the best path for traffic to take when passing from node to node in the mesh.

SAN

Storage Area Network. A network that allows access to storage devices specifically instead of the more general networking that can be used for any purpose. SANs allow servers to access devices such as tape libraries and disk arrays while presenting them to the operating system like any other locally attached device. Typically, a SAN is a network dedicated to storage devices and the servers that need access to them. The key reason for this is to reduce interference from normal LAN traffic during data transfer.

What are the drawbacks of connecting multiple computers to a shared network (Bus topology)?

The network cable in a bus topology is a shared communications medium, meaning that all computers attached to the network will receive any and all traffic sent on the network. Ex: like a one-lane road over a bridge, where cars must take turns travelling back and forth, this type of network performs well for a small number of computers but as it becomes more populated, it becomes exponentially more difficult to communicate with each other due to the collisions that occur when two or more computers attempt to transmit at the same time (half-duplex).

What is a key advantage of the Star Topology

Versatility. Instead of running cables from computer to computer, in a star topology, network cables re often run in the walls to a central closet. The owner must only connect the computer to the network outlet on the wall and then patch in the corresponding network cable to the central switch. This also means that a break in a single network cable will only impact one network device rather than the entire network.

What are traffic collisions?

When traffic collisions occur, all traffic must pause and wait for the line to clear before anyone can send again. this creates delays and degrades the performance of the network. To combat this problem, a ring network topology changes the way that computers know when to transmit and receive.

When are Mesh topoligies typically used.

Where communication within a network must be highly available and redundancy is needed. The nodes within a mesh network can communicate with each other, and these connections can be changed dynamically if one node were to fail. This behavior is often referred to as a self-healing network because the nodes in the mesh are aware of each other and can establish new connections around failed nodes as needed. Common use cases include wireless networks at home and in the office, as well as large collections of routers, such as on the internet.

WAN

Wide Area Network. Similar to a LAN, except that it covers a large geographical area within its network. This would be the case for worldwide businesses or government bodies. The internet is also an example of a WAN, as it can connect individual users across the globe. A WAN is a network that connects smaller networks, like LANs. WANs are able to link these smaller networks to transfer data over hundreds of thousands of miles, whereas a true LAN is only able to do so over its small network.

WLAN

Wireless local area network. Unlike LANs, wich are wired, WLANs use Wi-Fi to communicate with devices. This is a popular choice for small businesses, as it is easy and inexpensive to install and allows guests to use the network as well with hotspot service. Many private homes use WLAN in the form of WiFi, as it allows for multiple users to be connected to the network (and usually the broader internet), but not be tied down to a specific location in the home.

Define half-duplex mode (Bus topology)

You can either send or receive at any given time but cannot send and receive simultaneously.

Peer-to-peer

in a peer-to-peer model, or P2P, there is no individually designated server or client. Each machine on a network can act as both server and client, sometimes requesting data from other nodes and sometimes answering requests from others. Bitcoin and Tor are examples of peer-to-peer networks.