Network Topologies & Types | CompTIA Network+ N10-007 | 1.5a

In this video you will learn network topologies such as: logical vs. physical topologies; star, ring, mesh, bus, ad hoc, & infrastructure topologies. You are also going to learn about network types such as: LANs, WLANs, MANs, WANs, CANs, SANs, & PANs.

Network Topology

A network topology refers to the physical or logical layout of a network.  It defines the way different nodes are placed and interconnected with each other.  Alternatively, a network topology may describe how the data is transferred between these nodes.  

Wired Topologies

Logical Topology

A logical topology is a concept in networking that defines the architecture of the communication mechanism for all nodes in a network.  Using network equipment such as routers & switches, the logical topology of a network can be dynamically maintained and reconfigured.

Physical Topology

A physical topology refers to the interconnected structure of a local area network (LAN).  The method employed to connect the physical devices on the network with the cables, and the type of cabling used, all constitute the physical topology.

Star Topology

A star topology (also known as a star network) is one of the most common network setups.  In this configuration, every node connects to a central network device, like a hub, switch, or computer.  The central network device acts as a server and the peripheral devices act as clients.  In a star topology setup, either a coaxial or RJ-45 network cable is used, depending on the type of network card installed in each computer.

• Advantages
  • Centralized management of the network, through the use of the central computer, hub, or switch.
  • Easy to add another computer to the network.
  • If one computer on the network fails, the rest of the network continues to function normally.
• Disadvantages
  • May have a higher cost to implement, especially when using a switch or router as the central network device.
  • The central network device determines the performance & number of nodes the network can handle.
  • If the central computer, hub, or switch fails, the entire network goes down and all computers are disconnected from the network.

Ring Topology

A ring topology is a network configuration where device connections create a circular data path.  Each networked device is connected to two others, like points on a circle.  Together, devices in a ring topology are referred to as a ring network.  In a ring network, packets of data travel from one device to the next until they reach their destination.  Most ring topologies allow packets to travel only in one direction, called a unidirectional ring network.  Other permit data to move in either direction, called bidirectional.  Ring topologies may be used either LANs (local area networks) or WANs (wide area networks).  Depending on the network card used in each computer of the ring topology, a coaxial cable or an RJ-45 network cable is used to connect computers together.

• Advantages
  • All data flows in one direction, reducing the chance of packet collisions.
  • A network server is not needed to control network connectivity between each workstation.
  • Data can transfer between workstations at high speeds.
  • Additional workstations can be added without impacting performance at the network.
• Disadvantages
  • All data being transferred over the network must pass through each workstation on the network, which can make it slower than a star topology.
  • The entire network will be impacted if one workstation shuts down.
  • The hardware needed to connect each workstation to the network is more expensive than Ethernet cards and hubs/switches.

Bus Topology

A bus topology (also referred to as a line topology) is a network setup where each computer and network device is connected to a single cable or backbone.  Depending on the type of computer network card, a coaxial cable or an RJ-45 network cable is used to connect them together.

• Advantages
  • It works well when you have a small network.
  • It’s the easiest network topology for connecting computers or peripherals in a linear fashion.
  • It requires less cable length than a star topology.
• Disadvantages
  • It can be difficult to identify the problems if the whole network goes down.
  • It can be hard to troubleshoot individual device issues.
  • Bus topology is not great for large networks.
  • Terminators are required for both ends of the main cable.
  • Additional devices slow the network down.
  • If a main cable is damaged, the network fails or splits into two.

Wireless Topologies

Mesh Topology

A mesh topology is a network setup where each computer & network device is interconnected with one another.  This topology setup allows for most transmissions to be distributed even if one of the connections goes down.  It is a topology commonly used for wireless networks.

There are two forms of a mesh topology:

• Full Mesh Topology:  Every computer in the network has a connection to each of the other computers in that network.  The number of connections in this network can be calculated using the following formula:  n(n-1)/2 …(n is the number of computers in the network).
• Partially-Connected Mesh Topology:  At least 2 of the computers in the network have connections to multiple other computers in that network.  It is an inexpensive way to implement redundancy in a network.  If one of the primary computers or connections in the network fails, the rest of the network continues to operate normally.

• Advantages
  • Manages high amounts of traffic, because multiple devices can transmit data simultaneously.
  • A failure of one device does not cause a break in the network or transmission of data.
  • Adding additional devices does not disrupt data transmission between other devices.
• Disadvantages
  • The cost to implement is higher than other network topologies, making it a less desirable option.
  • Building & maintaining the topology is difficult and time consuming.
  • The chance of redundant connections is high, which adds to the high costs and potential for reduced efficiency.

Ad Hoc

An ad hoc network is a decentralized type of wireless network.  The network does not rely on a pre-existing infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks.  Instead, each node participates in routing by forwarding data for other nodes, so the determination of which nodes forward data is made dynamically on the basis of network connectivity and the routing algorithm in use.  In other words, devices connect on the fly, to share data between them without needing a network router, network switch or other network equipment to create the network.  The devices themselves act as the network equipment, creating a network between them.

Infrastructure

An infrastructure topology has specialized wireless equipment for permitting the wireless communications to take place.  Many homes today feature a wireless local area network (WLAN).  A wireless access point (WAP) allows the various computers to communicate with each other through the WAP acting like a hub device.  This WAP connects to the service provider of the home user with a wired connection.  For example, a coaxial cable could connect to the broadband cable service for high-speed Internet connectivity.

Networks Types

LAN (Local Area Network)

A LAN is a computer network within a small geographical area such as a home, school, computer laboratory, office building or group of buildings.  A LAN is composed of interconnected workstations and personal computers which are each capable of accessing and sharing data and devices, such as printers, scanners and data storage devices, anywhere on the LAN.  LANs are characterized by higher communication and data transfer rates and the lack of any need for leased communication lines. LANs can be wired or wireless LANs (WLANs).  Wired LAN can have high-speed connections with Ethernet unshielded twisted pair cable (UTP), shielded twisted pair cable (STP), or fiber.  Legacy LANs were often connected by coax cables.

WLAN (Wireless LAN)

A WLAN is a wireless computer network that links two or more devices using wireless communication to form a LAN within a limited area such as a home, school, computer laboratory, campus, or office building.  This gives users the ability to move around within the area & remain connected to the network.  Through a gateway, a WLAN can also provide a connection to the wider Internet.

CAN (Campus Area Network)

A CAN is a computer network made up of an interconnection of LANs within a limited geographical area.  The networking equipment (switches & routers) and transmission  media (optical fiber, CAT5 cabling, etc) are almost entirely owned by the campus tenant/owner:  an enterprise, university, government, etc.  A CAN is larger than a LAN but smaller than a MAN or WAN.

MAN (Metropolitan Area Network)

A MAN is a computer network that interconnects users with computer resources in a geographic region of the size of a metropolitan area. The term MAN is applied to the interconnection of LANs in a city into a single larger network which may then also offer efficient connection to a WAN. The term is also used to describe the interconnection of several LANs in a metropolitan area through the use of point-to-point connections between them.

WAN (Wide Area Network)

A WAN is a network that exists over a large-scale geographical area.  A WAN connects different smaller networks, including LANs and metro area networks (MANs). This ensures that computers and users in one location can communicate with computers and users in other locations.  WAN implementation can be done either with the help of the public transmission system or a private network. The internet is an example of a WAN. WANs are administered by several different internet service providers (ISPs), and the links are usually slower than LAN connections.

SAN (Storage Area Network)

A SAN is a computer network which provides access to consolidated, block-level data storage.  SANs are primarily used to access data storage devices, such as disk arrays and tape libraries from servers so that the devices appear to the operating system as direct-attached storage.  A SAN typically is a dedicated network of storage devices not accessible through the LAN.

PAN (Personal Area Network)

A PAN is a computer network for interconnecting electronic devices centered on an individual person’s workspace. A PAN provides data transmission among devices such as computers, smartphones, tablets and personal digital assistants. PANs can be used for communication among the personal devices themselves, or for connecting to a higher level network and the internet where one master device takes up the role as gateway. Examples of devices in a PAN are wireless headsets, keyboards, mice, printers, and bar code readers. A PAN may be wireless or carried over wired interfaces such as USB.