Lesson 2 2w5i5t

Certificate of Competency 2 (COC2): Set-up Computer Networks LESSON 2: NETWORK TOPOLOGY

Network Topology - A network topology is the arrangement of a network, including its nodes and connecting lines. Two Ways: 1. Physical Topology - is the actual geometric layout of workstations. 2. Logical Topology - Logical (or signal) topology refers to the nature of the paths the signals follow from node to node.

Bus Topology It is often used when network installation is small, simple or temporary. On a typical bus network the cable is just 1 or more wires with no active electronics to amplify the signal or it along from computer to computer. This makes the bus a ive topology. When 1 computer sends a signal up the wire all the computers receive the information but only one with the address that matches accepts the information, the rest disregard the message.

Bus Topology Layout

Advantages of Bus Topology 1) Easy to use and to understand.

2) Requires least amount of cable to connect the computers together. It is therefore less expensive than other cabling arrangements. 3) It is easy to extend a bus; two cables can be ed into 1 longer cable with a BNC (Bayonet Neill– Concelman), Barrel connector making a longer cable and allowing more computers to the network.

Disadvantages of Bus Topology 1) Heavy network traffic can slow a bus considerably as only 1 computer can send a message at a time. 2) It is difficult to troubleshoot the bus. A cable break or loose connector causes reflection and stops all the activity.

Star Topology In this kind of topology all the cables run from the computers to the central location where they are all connected by a device called hub or switch. Each computer on a star network communicates with a central device that resends the message either to each computer or only to the destination computer, example if it is a hub then it will send to all and if it is a switch then it will send to only destination computer. When network expansion is expected and when the greater reliability is needed, star topology is the best.

Star Topology Layout

Advantages of Star Topology 1) It is easy to modify and add new computers without disturbing the rest of the network. 2) The centre of the star network is a good place to diagnose the faults. 3) Single computer failure does not necessarily bring down the whole star network.

Disadvantages of Star Topology 1) If the central device fails, the whole network fails to operate. 2) Star networking is expensive because all network cables must be pulled to one central point, requires more cable than other network topologies.

Ring Topology In this type each computer is connected to the next computer with the last one connected to the first. Each retransmits what it receives from the previous computer. The message flows around the ring in one direction. The ring network does not subject to signal loss problem as a bus network experiences. There is no termination because there is no end to the ring.

Ring Topology Layout

Advantages of Ring Topology 1) Each node has equal access. 2) Capable of high speed data transfer.

Disadvantages of Ring Topology 1) Failure of one computer on the ring can affect the whole network. 2) Difficult to troubleshoot the network.

Mesh Topology A mesh network is a local network topology in which the infrastructure nodes connect directly, dynamically and nonhierarchically to as many other nodes as possible and cooperate with one another to efficiently route data from/to clients.

Mesh Topology Layout

Advantages of Mesh Topology 1. Each connection can carry its own data load 2. It is robust 3. A fault is diagnosed easily 4. Provides security and privacy

Disadvantages of Mesh Topology 1. Installation and configuration are difficult if the connectivity gets more 2. Cabling cost is more and the most in case of a fully connected mesh topology 3. Bulk wiring is required

Hybrid Topology A hybrid topology is a type of network topology that uses two or more differing network topologies. These topologies include a mix of bus topology, mesh topology, ring topology, star topology.

Hybrid Topology Layout

Advantages of Hybrid Topology 1.

2. 3. 4.

Fault detection and troubleshooting is easy in this type of topology. Its easy to increase the size of network by adding new components, without disturbing existing architecture. Hybrid Network can be designed according to the requirements of the organization and by optimizing the available resources. 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.

Disadvantages of Hybrid Topology 1.

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.

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Configuration and installation process needs to be very efficient.

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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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As hybrid architectures are usually larger in scale, they require a lot of cables, cooling systems, sophisticated network devices, etc.