Networks - Protocols (TC/IP Model) Flashcards
What is a protocol?
A set of rules for how devices communicate and how data is transmitted across a network
What do protocols do?
Cover how communication between two devices should start and end
How data should be organised
What the devices should do if data goes missing
How is data sent between networks?
Split into equal-sized packets
Each packet contains extra information such as the destination and source address and a checksum
What is a checksum?
It is used to find errors
How are network protocols divided?
They are divided into layers
What is the rule about the travel of data between layers?
Data can only be passed between adjacent layers
What is a layer?
A group of protocols which have similar functions
What are layers?
Self-contained - protocols in each layer do their job without needing to know what is happening in other layers
What do each layer do?
Each layer serves the layer above it (does the hidden work needed for the action above) - layer 4 triggers actions in layer 3 which triggers layer 2…
What are the 4 layers of the TCP/IP model?
Layer 4 - application layer
Layer 3 - transport layer
Layer 2 - internet layer
Layer 1 - link layer
What does layer 4 do?
The application layer provides networking services to applications - turning data into websites
What does layer 3 do?
The transport layer sets up communications between 2 devices - splits data into packets and checks packet are correctly sent and delivered
What does layer 2 do?
The internet layer adds IP addresses to data packets, directing them between devices and handling traffic - used by routers
What does layer 1 do?
Passes data over to the physical network and is responsible for how data is sent as electric signals over cables, wireless and other hardware and is responsible for interpreting signals using device drivers
What do device drivers do?
Act as a translator for signals between the OS and type device you are using
What are the advantages of using layers?
- Break down the communication into manageable chunks
- Layers can be changed without other layers being affected
- Having set rules for each layer forces companies to make compatible and universal software and hardware
How does breaking down networks into manageable chunks help?
It helps developers concentrate on only 1 area of the network without having to worry about the others
Why is having a set rules for each layer good?
It forces companies to make compatible and universal software and hardware so different bread can work with each other and will work in the same way
What is the application layer responsible for?
Files, email and data transfer
What are protocol examples of the application layer (layer 4)?
HTTP, HTTPS, FTP, SMTP and IMAP
What are protocol examples of the transport layer (layer 3)?
TCP and UDP
What is a protocol example of the internet layer (layer 2)?
IP
What are the protocol examples of the link layer (layer 1)?
Wi-Fi and Ethernet
What does HTTP stand for?
Hyper Text Transfer Protocol
What does HTTPS stand for?
Hyper Text Transfer Protocol Secure
What does FTP stand for?
File Transfer Protocol
What does IMAP stand for?
Internet Message Access Protocol
What does SMTP stand for?
Simple Mail Transfer Protocol
What is HTTP used for?
Used by web browsers to access websites and communicate with web servers
What is HTTPS used for?
A more secure version of HTTP
Encrypts all information sent and received
What is FTP used for?
Used to access, edit and move files between devices on a network - access files on a server from a client computer
What is IMAP used for?
To retrieve emails from a server
What is SMTP used for?
To send emails and transfer emails between servers
What are TCP and UDP?
Transport layer (layer 3) protocols which control the packaging or unpackaging of data
What does TCP stand for?
Transmission Control Protocol
What does UDP stand for?
User Datagram Protocol
What does TCP do?
Establishes a connection between the sending and receiving devices
Splits the data into numbered packets - can be reassembled even if they don’t arrive in order
Communicates with the receiving device to make sure all the packets have been transferred correctly - if missing/corrupted they will be resent
Sending device gets confirmation when transfer is complete
What does UDP do?
Splits data into packets without numbering them
The packets are read by the receiving device in the order they arrive (even if it’s wrong)
Only sends each packet once and doesn’t check
Saves time but no way of knowing if packets are missing in transmit
What are the differences between TCP and UDP?
TCP - numbers packets (correct order), resends data if corrupt or missing, longer time to transmit
UDP - doesn’t number packets (wrong order), doesn’t resend data, shorter time to transmit
What are situations where UDP would be more suitable?
Applications that need fast, efficient transmission - live streaming - better to have a hiccup in video quality than have a delay in the live stream
What are situations where TCP would be more suitable?
When you need a reliable connection - downloading files - missing data packets can cause files to be corrupt and unusable and you wouldn’t want to have to re-download the whole file
What does IP stand for?
Internet protocol
What is IP used for?
It operates on the internet layer (layer 2) and establishes connections between routers and handles network traffic
What are IP addresses?
Unique numbers assigned to every device connected to an IP network
What does the IP do with IP addresses?
It adds them to the header of each packet in the internet layer
What is IP responsible for?
Responsible for directing data packets to their destination across the internet or other IP networks via a process called packet switching
What is packet switching?
An efficient use of the network because there are so many possible routes that each packet can take - packets can reach their receiving device quickly even if there is heavy traffic
What happens in packet switching?
- Each packet is sent between a series of routers
- Each router uses the IP address to decide which router to send the packet next
The way the data is sent depends on data traffic - packet can take different routes
What happens if a router receives too many packets at once (packet switching)?
It may prioritise some packets over others
What is Wi-Fi?
A family of protocols often used in WLANs that operates on the link layer
What are frames?
Units of data sent on the link layers (instead of packets)
What are the 2 frequency bands that Wi-Fi uses?
2.4 GHz
5 GHz
What is good about using 2.4 GHz?
Has a greater range and is better and getting through walls
What is good about using 5 GHz?
It is faster over short distances
What happens to the bands?
They are split into numbered channels
What is different about the channels in the 2.4 GHz bands?
They overlap
What causes interference?
Networks using adjacent or overlapping channels
What is Ethernet?
It also handles the transmission of data between devices but is specifically for wired networks
