NETWORK TOPOLOGIES (NETWORK TOPOLOGY)

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Anon nepal presents

Anon nepalpresentsA TOTAL GUIDE ABOUTNETWORK TOPOLOGIES

HimanshuWhat you will learn today?Introduction To Network TopologyFactor Choosing Network TopologyTypes of Network TopologyBibliography + Useful Sites

NETWORK TOPOLOGIESTopology refers to the layout of connected devices on a network.

Simply its a :Layout of a networkand how different nodes in a networkare connected to each other and how they communicate.

continue

CONCEPTComputer network topology is the way various components of a network (like nodes, links, peripherals, etc) are arranged. Network topologies define the layout, virtual shape or structure of network, not only physically but also logically. The way in which different systems and nodes are connected and communicate with each other is determined by topology of the network.Topology can be physical or logical.Physical Topologyis the physical layout of nodes, workstations and cables in the network; whilelogical topologyis the way information flows between different components.

In general, physical topology relates to a core network whereas logical topology relates to basic network.

FACTORS WHILE CHOOSING TOPOLOGIESScale of your project (in terms of number of components to be connected)Amount of traffic expected on the network.Budget allotted for the network i.e. amount of money you are willing to invest.Required response time.

TOPOLOGY TYPESThere are two basic categories of network topologies:physical topologies and logical topologies.PHYSICAL TOPOLOGIES

CONCEPTThe physical topology of a network is the actual geometric layout of workstations. There are several common physical topologies, as I am describing below and as shown in the figure.

Simply, I can say Physical topology is the physical layout of nodes on a network

Peps, Now I will take you to the next level. Lets learn about there types

continueTYPES OF PHYSICAL TOPOLOGIES1.FULLY CONNECTED

DESCRIPTIONA fully connected network, complete topology, or full mesh topology is a network topology in which there is a direct link between all pairs of nodes. Networks designed with this topology are usually very expensive to set up, but provide a high degree of reliability due to the multiple paths for data that are provided by the large number of redundant links between nodes. This topology is mostly seen in military applications.ADVANTAGESA fault in one terminal on the network will not effect the restWhen network usage is high, data packets can be transmitted via different cables, thereby reducing network clogging - keeping data transfer rates at an acceptable level..DISADVANTAGESA large amount of cabling is required2. BUS

CONCEPT In this topology everyworkstation is connected to a main cable called the bus. Therefore, in effect, each workstation is directly connected to every other workstation in the network.15DESCRIPTIONSingle cable connects all network nodes without intervening connectivity devicesDevices share responsibility for getting data from one point to anotherTerminators stop signals after reaching end of wirePrevent signal bounceInexpensive, not very scalableDifficult to troubleshoot, not fault-tolerant

ADVANTAGESWorks well for small networksRelatively inexpensive to implementEasy to add to it

DISADVANTAGESManagement costs can be highPotential for congestion with network traffic

3. STAR

CONCEPTIn thistopology, there is a central computer or server to which all the workstations are directly connected. Every workstation is indirectly connected to every other through the central computer.

DESCRIPTIONAny single cable connects only two devicesCabling problems affect two nodes at mostRequires more cabling than ring or bus networksMore fault-tolerantEasily moved, isolated, or interconnected with other networksScalableSupports max of 1024 addressable nodes on logical network

ADVANTAGESGood option for modern networksLow startup costsEasy to manageOffers opportunities for expansionMost popular topology in use; wide variety of equipment available

DISADVANTAGESHub is a single point of failureRequires more cable than the bus

4. RING

CONCEPT In this topology, the workstations are connected in a closed loop configuration. Adjacent pairs of workstations are directly connected. Other pairs of workstations are indirectly connected, the data passing through one or more intermediate nodes.

DESCRIPTIONEach node is connected to the two nearest nodes so the entire network forms a circleOne method for passing data on ring networks is token passingEach workstation transmits data

ADVANTAGESEasier to manage easier to locate a defective node or cable problemWell-suited for transmitting signals over long distances on a LANHandles high-volume network trafficEnables reliable communication

DISADVANTAGESExpensiveRequires more cable and network equipment at the startNot used as widely as bus topologyFewer equipment optionsFewer options for expansion to high-speed communication

5. MESH

CONCEPT In this topology employs either of two schemes, called full mesh and partial mesh. In the full mesh topology, each workstation is connected directly to each of the others. In the partial mesh topology, some workstations are connected to all the others, and some are connected only to those other nodes with which they exchange the most data

DESCRIPTION Each of the network node, computer and other devices, are interconnected with one another. Every node not only sends its own signals but also relays data from other nodes. In fact a true mesh topology is the one where every node is connected to every other node in the network. This type of topology is very expensive as there are many redundant connections, thus it is not mostly used in computer networks. It is commonly used in wireless networks. Flooding or routing technique is used in mesh topology.

ADVANTAGESData can be transmitted from different devices simultaneously. This topology can withstand high traffic.Even if one of the components fails there is always an alternative present. So data transfer doesnt get affected.Expansion and modification in topology can be done without disrupting other nodes.

DISADVANTAGESThere are high chances of redundancy in many of the network connections.Overall cost of this network is way too high as compared toother topologies.Set-up and maintenance of this topology is very difficult. Even administration of the network is tough.

6. TREE

CONCEPTIn thistopology uses two or more star networks connected together. The central computers of the star networks are connected to a main bus. Thus, a tree network is a bus network of star networks.

DESCRIPTION Tree Topology integrates the characteristics of Star andBus Topology. Earlier we saw how in Starnetwork Topology, computers (nodes) are connected by each other through central hub. And we also saw in Bus Topology, work station devices are connected by the common cable called Bus. After understanding these two network configurations, we can understand tree topology better. In Tree Topology, the number of Star networks are connected using Bus. This main cable seems like a main stem of a tree, and other star networks as the branches. It is also calledExpanded Star Topology. Ethernet protocol is commonly used in this type of topology. The diagram below will make it clear.

ADVANTAGESIt is an extension of Star and bus Topologies, so in networks where these topologies can't be implemented individually for reasons related to scalability, tree topology is the best alternative.Expansion of Network is possible and easy.Here, we divide the whole network into segments (star networks), which can be easily managed and maintained.Error detection and correction is easy.Each segment is provided with dedicated point-to-point wiring to the central hub.If one segment is damaged, other segments are not affected.

DISADVANTAGESBecause of its basic structure, tree topology, relies heavily on the main bus cable, if it breaks whole network is crippled.As more and more nodes and segments are added, the maintenance becomes difficult.Scalability of the network depends on the type of cable used.

7.HYBRID

CONCEPTHybrid networks use a combination of any two or more topologies, in such a way that the resulting network does not exhibit one of the standard topologies (e.g., bus, star, ring, etc.). For example a tree network connected to a tree network is still a tree network topology. A hybrid topology is always produced when two different basic network topologies are connected. Two common examples for Hybrid network are:star ring networkandstar bus networkADVANTAGESReliable: Unlike other networks, fault detection and troubleshooting is easy in this type of topology. The part in which fault is detected can be isolated from the rest of network and required corrective measures can be taken, WITHOUT affecting the functioning of rest of the network.Scalable:Its easy to increase the size of network by adding new components, without disturbing existing architecture.Effective:Hybrid topology is the combination of two or more topologies, so we can design it in such a way that strengths of constituent topologies are maximized while there weaknesses are neutralized.

DISADVANTAGESComplexity of Design:One of the biggest drawback of hybrid topology is its design. Its not easy to design this type of architecture and its 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

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