Network Toplogies

Network Topologies

In this blog we’ll discuss the various network topologies and the hardware and software required to run the network as well we will look at costing for each topology.

Topologies are building blocks for designing a computer network. A technician needs to understand how networks are designed in order to work on computers that are part of a network.

A topology can be categorised into logical and physical topologies. Firstly, we’ll look at the logical topology in detail.

Logical topologies

     Logical Topologies:

Determines how the host access the medium to communicate across the network, such as cable or airwaves. There are two common types of logical topologies:

~Broadcast Topology

~Token Passing

Broadcast Topology:

A host broadcasts a message to all other hosts on the same network segment. There is no order that hosts must follow to transmit data. Messages are sent on a First In, First out (FIFO). Ethernet is based on this topology.

Token Passing:

Controls network access by passing an electronic token sequentially to each host. When a host receives the token, it can send data on the network. If the host has no data to send, it passes the token to the next host and the process repeats itself.

Physical Topologies:

Physical topology is the physical layout of the components on the network. There are various other physical topologies:

~~      Bus

~~      Ring

~~      Star

~~      Hierarchical or Extended Star Topology

~~      Mesh Topology

~~      Hybrid

HYBRID

Hybrid topology is an integration of two or more topologies to form a resultant topology which has many advantages (as well as many disadvantages) of all the constituent basic topologies rather than having characteristics of one specific topology 

 ■ A Star ring network consists of two or more star topologies connected using a multi-station access unit as a centralized hub.
■ A Star Bus network consists of two or more star topologies connected using a bus trunk (the bus trunk serves as the network's backbone).

Advantages

  ~~Reliable: Unlike other networks, fault detection and troubleshooting is easy in this type of topology.

 

~~Scalable: It’s easy to increase the size of network by adding new components, without disturbing existing architecture.

~~Flexible: Hybrid Network can be designed according to the requirements of the organization and by optimizing the available resources. Special care can be given to nodes where traffic is high as well as where chances of fault are high. 

Disadvantages

~~Complexity of Design: One of the biggest drawback of hybrid topology is its design. It’s not easy to design this type of architecture and it’s a tough job for designers. Configuration and installation process needs to be very efficient.

~~Costly Hub: The hubs used to connect two distinct networks, are very expensive. These hubs are different from usual hubs as they need to be intelligent enough to work with different architectures and should be function even if a part of network is down

~~Costly Infrastructure: As hybrid architectures are usually larger in scale, they require a lot of cables, cooling systems, sophisticate network devices. 

                                               

 STAR/EXTENDED STAR

In the star topology, all computers and other network devices connect to a central device called a hub or switch. Each connected device requires a single cable to be connected to the hub, creating a point-to-point connection between the device and the hub.

Using a separate cable to connect to the hub allows the network to be expanded without disruption to the network. A break in any single cable will not cause the entire network to fail

 Workstations are connected to central device with a point-to-point connection. So it can be said that every computer is indirectly connected to every other node by the help of “hub.

Advantages

~~         Easy to install and wire.

~~        No disruptions to the network when connecting or removing devices.

~~        Easy to detect faults and to remove parts.

~~        Good performance.

Disadvantages:

~~        requires more cable length than a linear topology.

~~        If the hub, switch, or concentrator fails, nodes attached are disabled.

~~        Expensive to install.

~~        Extra hardware required.

Extended star

When a star network is expanded to include an additional networking device that is connected for the main networking device, which is called extended star topology.

The extended star topology adds sub-central devices that are connect to the central device. This type of topology is advantageous for large networks and provides functionality for the organization and sub-netting of the IP address allocation within the network. The extended star topology is most suitable for large networks that may span an entire building.

Advantages: 

 ~~  It has the same performance and reliability found in a star topology with the addition of the ability to cover greater distances from the central switch to the end nodes by adding repeaters or additional connectivity devices to the segments

 ~~ The extended-star topology makes more sense in a larger physical environment and allows you to reduce degradation of signal in places such as the far reaches of a large corporate office.

~~  Failures are easy to find.

 ~~   A star network with an additional networking device connected to the main networking device.

     

 Disadvantages

   ~~ Network has failures. 

    Any given mode in the LAN has one or more physical links to other devices in the network.

Example:
In a school or college the workstations in each computer room could from one of stars within an extended star topology. 

~~ High dependence of the system on the functioning of the central hub. Network size is limited by the number of connections that can be made to the hub, and performance for the entire network is capped by its throughput.

 

MESH TOPOLOGY

 

Every device has a dedicated point-to-point connection to every other device. It is therefore implemented in a limited style for example a backbone linking the main computers of a hybrid network that can include several other topologies. Mesh topology introduces the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. A mesh network in which every device connects to every other is called a mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.

 Advantages

~~The use of dedicated connection ensures that each link can carry its own data load 

~~If one link becomes unusable it does not incapacitate the entire system

 Disadvantages

~~Large amount of cabling and the number of input and output ports needed.

~~Installation and reconfiguration are difficult.

 

Ring Topology

 

A ring topology is a simple connection where the hosts are connected in a physical ring or circle. Adjacent pairs of nodes, a network device with a unique network address, are directly connected. Information travels around the loop or circle in one direction.

Advantages 

~~Ring topologies generally use coaxial cables or fibre optics. 

~~There are no collisions in a ring topology network. 

~~It’s a much organized topology, data flows in one direction at a very high speed. 

~~There’s also an equal access to resources for all computers and additional components doesn’t affect the performance of the network.

 Disadvantages

   

~~It’s much slower than a star topology due to the fact that the packets must pass through all the computers between source and destination. 

~~The network will be affected if one workstation or port goes down. 

~~It’s a network that is not independent, its functions on the wire that connects all the computers 

 

Bus Topology

A Bus Topology (AKA the Line Topology) is a network setup in which all computers and other devices (AKA Nodes) are connected to a central cable (AKA the Backbone). It is one of the more reliable Network topologies however it is not without its shortcomings as show in the following points:

Advantages

~~ It is easy to set up and extent a Bus Network.

         

~~Compared to other Topologies Cable consumption on a Bus Topology is minimal.

~~Bus Networks are cost effective compared to other Topologies.

~~Bus Topologies are perfect for LAN’s and small office environments.

Disadvantages 

~~You are limited on the cable length and amount of nodes.

~~If the Backbone is damaged then the Network will either fail or divide into two smaller networks.

~~Terminators are required to cease transmissions at each end of the Backbone. 

More the devices slower the network.

~~A Bus topology network is not suitable for heavy traffic.

~~identifying a problem is difficult if the entire network is down. With time an increase in maintenance costs can be expected

HARDWARE AND SOFTWARE

Network software

<>NetInfo

Scan your network and diagnose network issues.

<>iStatus Monitor Desktop Edition

Receive relevant Internet and network information.

<>Technitium MAC Address Change

Replace your Network Interface Card's Media Access Control (MAC) Address easily.

<>Wireless Network Watcher

Display all the computers which are connected to your system.

<>CommView for WiFi

Point out network problems and troubleshoot from a detailed picture of network traffic.

 HARDWARE

 

1000BASE-TX is similar to 1000BASE-T but uses two pairs of wires, instead of four, for data transmission: one for sending data at speeds of 500 Mbps, and another for receiving data at comparable speeds.  

 

The Cat 5e standard provides performance of up to 100 MHz and can be used up to a maximum length of 100 meters.

Unshielded Twisted Pair  :  is the copper media, inherited from telephony, which is being used for increasingly higher data rates, and is rapidly becoming the  standard for horizontal wiring, the connection between, and including, the outlet and the termination in the communication closet. 

Shielded Twisted Pair :  it can greatly improve the signaling rate in a given transmission scheme Twisting provides cancellation of magnetically induced fields and currents on a pair of conductors.

 

Server

Central, and usually the largest, and most powerful computer in a network that houses the server software, stores and manages common (network) data and supplies it to the individual workstations (clients), and provides shared services (access to internet).


 

Budget

Product	Price
Software	15000
Server	6600
i5 Laptops (5)	50000
Ram 8gb DDR3	707
Graphics Card	2500
Motherboard	3500
Switch	5735
1000 bs-tx	192
CAT 5 UPT	344
UTP	144
Router	550

Network	Basic Costs
Ring Topology	R8000-R11000
Mesh Topology	R10000
Hybrid Topology	R9000-R13000
Bus Topology	R6000-R9000
Star	R7000

references

~~ http://www.ianswer4u.com/2011/05/ring-topology-advantages-and.html
~~https://kane18.wordpress.com/2007/01/11/advantages-and-disadvantages-of-a-bus-ring-star-network/
~~https://kane18.wordpress.com/2007/01/11/advantages-and-disadvantages-of-a-bus-ring-star-network/
~~ https://www.techopedia.com/definition/5538/network-topology

~~ https://computer.howstuffworks.com/internet/social-networking/inf

~~https://whatis.techtarget.com/definition/network-topology