Networks Flashcards
Define circuit switching
A method of transmitting data over a wide area network where a direct link is established between two devices on the network and maintained for the entire duration of communication
Define packet switching
A method of transmitting data over a wide area network by breaking streams of data into packets which are sent independently of each other via optimal routes and reassembled at the destination
State the characteristics of circuit switching
- a direct link is created between two devices
- reserves bandwidth
- all packets use the same path
- requires devices to transfer and receive data at the same rate
State and explain one advantage and one disadvantage of circuit switching
advs
- exclusive connection means packets arrive in the same order which simplifies process of reconstructing the message
Disadvs
- not efficient as bandwidth is wasted in periods where no data is being transmitted
- electrical interference is produced from switches used to connect and disconnect circuits which can corrupt or lose data
- does not support store and forward transmission which does not allow for error detection
State the characteristics of packet switching
- packets are sent independently
- packets are sent via route which is least congested
- no physical path
- does not reserve bandwidth
Explain the advantages and disadvantages of sending packets via the least congested route
adv
It maximises bandwidth as all of it is being used
Disadvs
- does not guarantee quality of transmission
- packets may arrive our of order which makes reassembling process more complex
State and explain two advantages of packet switching
- more affordable because it requires less complex infrastructure
- more efficient because all the bandwidth can be used at once
- can easily respond of parts of the network fail
- supports store and forward transmission which allows for error detection and ensures data integrity
Give an example of where circuit switching os used
Traditional telephone networks
What is the internet?
A collection of interconnected networks, routers, cables, satellites and other hardware across the world
What is the World Wide Web?
A collection of files with information stored in hypertext (webpages) and other associated files
A service run on the internet
State 3 features to consider when networking
- Sequencing packets on arrival
- Splitting data into smaller packets and frames
- Sending frames between devices on a LAN
- Simplex and duplex transmissions
- Error-checking packets and frames on arrival and requesting data to be resent if necessary
- Encryption, security and authentication of users and data
- Using wireless connectivity with frequencies and channels
What is the concept of layering?
To divide the complex task of networking into smaller, simpler tasks that work in tandem with each other
Describe the concept of layering
- Hardware and software in each layer have defines responsibility
- Each layer provides a service the the layer above it
State two advantages of layering
- Reduces complex problem into smaller sub-problems
- Devices can be manufactured to operate at a particular layer
- Products from different vendors will work together
What is meant by the TCP/IP stack?
A set of networking protocols, consisting of four layers working together
State two protocols used and an example of a network application that operate at the application layer
E..g web browser, email programs
Protocols: FTP, HTTP, HTTPS, SMTP, IMAP
Describe the purpose of the transport layer
To set up communication between two hosts and agree on settings such as language and packet size
Protocols: TCP, UDP
Describe the purpose of the internet layer
To address and package data for transmission
Protocols: IP
Describe the purpose of the link layer
To facilitate the transmission of binary via any media
Protocols: Ethernet
Cables: copper twisted pair, fibre optic, Wi-Fi
What is a MAC address?
A 48-bit value coded into a device by a network interface card
- usually written as a 12 digit hexadecimal number
Why do we need MAC addresses?
It tells us the specific device that is requesting or receiving data
