Networking Devices

Networking Topologies

Computer Networking

Networking Devices

• Hubs• Switch• Router

• Modem• Repeater• Multiplexer

Networking Topologies

• Bus Topology

• Star Topology• Ring Topology

Networking Devices

Networking=Working together

The devices that help the network to be

linked to each other

Objective of helping share data and/or

hardwares or softwares

Hubs

connects two or more devices without having to connect to each other directly uses twisted pair cable basic function: forward the data it received from a connected device to all other connected devices regardless of whether the data is destined for the device. creates bottleneck on larger busy networks comes in variety of shapes and sizes:

workgroup hubs: consists of 5-8 portshigh density devices: consists up to 32 ports

Hubs: how they work!!

Hubs

Are of three types:1. Passive Hubs:

provides a pathway for signals to traveldoes not need power to operate

2. Active Hubs:provides a pathway for signals to travelregenerates the signals before passing it onrequires power to operate

3. Intelligent Hubs:performs all the jobs of active and passivehelps in troubleshooting by pointing the actual location of the problem

Switch

• forwards data packages to only the destined device• checks the MAC address found in the NIC to do so• by forwarding the data to only the destined device, it reduces the number of collision in the network• uses three methods to deal with the data’s as they arrive:

1. Cut through: o Begins to forward the package as soon as it arriveso No error checking performedo Packet is moved quickly

2. Store and forwardo Waits to receive the entire package before forwarding ito Basic error checking is performed

3. Fragment Freeo Built on the speed advantage of cut througho Forwards package in fragments

Switch: how it works!!

Router

• increasingly common sight in any networking environment• most commonly used to connect a home computer to an ISP• used to create large networks by joining two network segments• derives it’s name from the fact that it can route data from one network to another• when it receives a packet of data, it reads the header of the packet to determine the destination address• when address is determined, it looks in it’s routing table to see whether it knows how to reach the destination•If it does know how to reach the destination it then forwards the data to the next hop on the route•The next hop could be the final destination or another router

Router: how it works!!

Modem

• short for modulizer-demodulizer• converts data being used by a computer into an audio signal that is able to be transmitted over a phone line•When the signal gets to its intended destination, another modem then reconverts the signal back into data • the process of converting data into audible sound is known as modulation• converting it back to the data is known as demodulation• Modems provide a relatively slow method of communication• the fastest modem available on the market today has a maximum speed of 56Kbps• unsuitable for downloading large files.

Modem: how it works!!

Repeaters

• send signals over long distances• function of a repeater is to receive incoming signals or a packet of data, regenerate the signals to their original strength and retransmit them• helps computers maintain stronger wireless signals by taking in signals from routers and remitting them• primary advantage of using a wireless repeater is that it can improve wireless signal strength without having to move a computer or router• further a computer is from the wireless router it connects to, the weaker its wireless signal will tend to be• Placing a wireless repeater at some point between a computer and the router it connects to can enable the computer to receive a stronger signal•Another benefit of using a wireless repeater is that it can help you reduce the impact of obstructions that may impact your wireless connection• Physical objects can weaken wireless signals so we should place a repeater in a location where few objects rest between it

Multiplexer

• accepts multiple inputs and allows only one to go through as an output• receiving end accepts this complex signal and reconverts it into its individual components• multiplexing is used in both digital and analog data transmission• provides great cost advantages, since it reduces the need for additional wires and/or communication channels but, the initial cost of setting it up is expensive• multiplexing can slow down the communication process, since shifting from one frequency to another causes time delays• another disadvantage of it requires constant source of electrical power to operate

Multiplexer

Multiplexers are of three types:1. Frequency division multiplexing :

• divides a single bandwidth into various different frequencies so it can be used by multiple users

• each different frequency carries a separate signal at the same time

2. Time division multiplexing :• allows multiple signals to travel across the same transmission

channel• but allocates different time slots to each.

3. Dense wavelength division multiplexing :• is a version of frequency division multiplexing• it sends colored lasers to transmit data over the same bandwidth

Network Topologies

• network layout of connected devices

•Arrangement of network

•Layout of connected device

Bus topology: the setup!!

Advantages

Easy to add and remove nodes

Requires small amount of cable compared to other

topologies so is less expensive and easier to setup and

troubleshoot.

Bus topology

Disadvantages

A failure in the central line means the whole network will

go down.

Only one route for data to take so will performance will

decrease as more data is transmitted.

Bus topology

Ring Topology: the setup!!

Advantages

As all the data can only travel in one direction the

transmission of messages is simple and high rates can

be achieved.

There is no dependence or need of a central computer

or mainframe.

Ring Topology

Disadvantages

If one node or line fails then data cannot continue to be

transmitted between all the rest of the nodes in the

network.

Harder to add new nodes into the system, requires the

network to be disrupted.

Ring Topology

Star Topology: its setup!!

ADVANTAGES

More secure connection as data is sent directly between

nodes (unlike ring networks)

A failure of the cable will only affect one node, hence faults

are easier to pinpoint.

Easy to add new nodes without any disruption

Star Topology

DISADVANTAGES

Requires and is dependant upon a central computer.

Requires more cable and is therefore more expensive to

setup.

Star Topology