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