NETWORK TOPOLOGY

HOW MANY KINDS OF NETWORKS?

Depending on one’s perspective, we can classify networks in different ways• Based on transmission media: Wired (UTP,

coaxial cables, fiber-optic cables) and Wireless

• Based on network size: LAN and WAN (and MAN)

• Based on management method: Peer-to-peer and Client/Server

• Based on topology (connectivity): Bus, Star, Ring, Mesh/Fully Connected, Tree, Wireless

NETWORK TOPOLOGIES

Topology - Physical and logical network layout Physical – actual layout of the computer

cables and other network devices Logical – the way in which the network

appears to the devices that use it. Common topologies: – Bus, ring, star,

mesh and wireless

BUS TOPOLOGY

Bus topology is one the easiest topologies to install, it does not require lots of cabling.

Bus topology uses one common cable (backbone) to connect all devices in the network in linear shape.

In this type of network topology, all the nodes of a network are connected to a common transmission medium having two endpoints.

A linear bus topology consists of a main run of cable with a terminator at each end

Systems connect to this backbone using T connectors or taps. Coaxial cablings ( 10Base-2, 10Base5) were popular options years

ago. Bus topology is multipoint .

BUS TOPOLOGY

BUS TOPOLOGY - ADVANTAGES

Easy to connect a computer or peripheral to a linear bus.

Requires less cable length than a star topology Easy to implement and extend. Failure of one of the station does not affect others. Good compromise over the other topologies as it

allows relatively high rate of data transmission. Well suited for temporary networks that must be set

up in a hurry.

BUS TOPOLOGY - DISADVANTAGES Entire network shuts down if there is a break in the main

cable. Terminators are required at both ends of the backbone cable. Difficult to identify the problem if the entire network shuts

down. Not meant to be used as a stand-alone solution in a large

building. Does not cope well with heavy traffic rates Difficult to administer/troubleshoot. Limited cable length and number of stations. A cable brake can disable the entire network; no redundancy. Maintenance cost may be higher in the long run. Performance degrade as additional computers are added.

RING TOPOLOGY

Ring topology is one of the old ways of building computer network design

In ring network topology computers and other networking devices are attached to each other in such a way that they have devices adjacent to each other (Left and right side).

All messages are travelled in the same direction either clockwise or anticlockwise; so that means ring topology is unidirectional.

In case of failure of any device or cable the whole network will be down and communication will not be possible.

In ring topology, each device has a dedicated point connection only with two devices on either side of it.

RING TOPOLOGY

RING TOPOLOGY - ADVANTAGES

                                                    

All nodes on the network have equal chance of transmitting data.   

Growth of system has minimal impact on performance.

Cable faults are easily located, making troubleshooting easier

Ring networks are moderately easy to install.

RING TOPOLOGY - DISADVANTAGES Expansion to the network can cause network

disruption If one of the nodes ones down then the whole

network may go Difficult to add and delete nodes to /from the

ring.

STAR TOPOLOGY

This is the most commonly used or implemented network topology design you will come across in LAN computer networks.

All computers/devices connect to a central device called hub or switch, using UTP of STP cables.

Each device requires a single cable point-to-point connection between the device and hub.

The hub is the single point of failure.

STAR TOPOLOGY

STAR TOPOLOGY - ADVANTAGES Easy to install and wire. No disruptions to the network when connecting

or removing devices. Easy to detect faults and to remove parts. Cable failure affects only a single user.

STAR TOPOLOGY - DISADVANTAGES Requires more cable length than a linear

topology. If the hub, switch, or concentrator fails, nodes

attached are disabled. More expensive than linear bus topologies

because of the cost of the hubs, etc. More difficult to implement.

TREE OR EXPANDED STAR TOPOLOGY

A tree topology combines characteristics of linear bus and star topologies.

It consists of groups of star-configured workstations connected to a linear bus backbone cable.

Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.

TREE OR EXPANDED STAR

TREE TOPOLOGY - ADVANTAGES Point-to-point wiring for individual segments. Supported by several hardware and software venders.

TREE TOPOLOGY - DISADVANTAGES Overall length of each segment is limited by the

type of cabling used. If the backbone line breaks, the entire segment

goes down. More difficult to configure and wire than other

topologies.

FULLY CONNECTED OR MESH TOPOLOGY

Each computer connects to every other. High level of redundancy. Rarely used.

Wiring is very complicated Cabling cost is high Troubleshooting a failed cable is tricky A variation hybrid mesh – create point to

point connection between specific network devices, often seen in WAN implementation.

FULLY CONNECTED OR MESH TOPOLOGY

MESH TOPOLOGY - ADVANTAGES Provides redundant path between devices. The network can be expanded without

disruption to current users.

MESH TOPOLOGY - DISADVANTAGES Requires more cable than the other LAN

topologies. Complicated implementation.

WIRELESS TOPOLOGY

Uses radio frequency instead of cable as the transmission media and wireless access points instead of hubs for connecting devices to a network.

Do not require physical cabling Particularly useful for remote access for laptop

users Eliminate cable faults and cable breaks. Signal interference and security issue.

WIRELESS TOPOLOGY

WIRELESS TOPOLOGY - ADVANTAGES Allows wireless remote access The network can be expanded without

disruption to current users.

WIRELESS TOPOLOGY - DISADVANTAGES Potential security issues associated with

wireless transmissions. Limited speed in comparison to other network

topologies.

IEEE AND NETWORKING STANDARDS

Institute of Electrical and Electronic Engineers (IEEE) developed a series of networking standards Networking technologies developed by

manufacturers are Compatible Cabling, networking devices and

protocols are all interchangeable under the banner of a specific IEEE

IEEE AND NETWORKING STANDARDS