Networks 7- OSI model 7 layers Flashcards
Describe the APPLICATION LAYER (LAYER 7)
*Window for users and application services
*Receives command
*Contains commonly needed functions like resource sharing and device redirection.
*Data is packed for the journey
Describe what the Presentation layer (layer 6) does?
- Extracts data and converts it into the form required.
- Translation-translates the data type into a common format.
- Encryption/decryption for increased security
- Compression of the data to optimise bandwidth
Desribe theSession layer (layer 5)
- Session establishment, maintenance and termination
- Allow 2 application processes on different machines to use a connection called a session
*Performs functions for communication in the network
*Security
*Name recognition
*Logging
*This layer remembers everyone who passes by
Describe what the transport layer (LAYER 4) does
- Security
- Validity
- Scans the data to ensure it is reliable and valid (error free)
- Data broken into segments
- Security firewalls are in this layer
- Data that do not pass are destroyed
NETWORK LAYER (layer 3)
*Breaks segments into packets
* Routing (finding the quickest path for the data)
*Packet filtering routers and firewalls are sometimes in this layer
* The lower the firewall in the layer is = more secure network
*Adds the source and destination IP address (Internet protocol)
What does the Datalink layer (layer 2) do and what it includes
*Switch/hub
*MAC address contains 12 hexadecimal digits and prevents collisions
*Packets are turned into frames for specific networks
*Error free data from one node to another over the physical layer
Describe the Physical layer (layer 1)
*Transforms the frames into bits and sends it over the network through physical hardware
*Data is logically arranged and encoded in this layer
*The data is then received by another computer’s physical layer
What is the importance of the OSI model?
Importance of model:
*Standardisation-Provides common language and structure, as it is a standard reference model.
*Troubleshooting- easy to identify which layer is causing the problem, so easy troubleshooting.
*Flexibility-Can be adapted to different types of networks. Can be used for different purposes.
*Communication as it provides a common language and structure.
What is the OSI
OSI- Open Systems Interconnection is a conceptual framework which describes the different layers and protocols within a network.
Who was the OSI model made by?
Developed by the International Organisation for Standardisation (ISO)
Which protocols are in the application layer (layer 7)?
Hypertext Transfer Protocol (HTTP)
File Transfer Protocol (FTP)
Simple Mail Transfer Protocol (SMTP)
Protocols within the presentation layer (layer 6)
Secure Sockets Layer (SSL)
Transport Layer Security (TLS)
Protocols within the session layer (layer 5)
NetBIOS, Session Control Protocol (SCP)
Remote Procedure Call (RPC).
Protocols within the transport (layer 4)
Transmission Control Protocol (TCP), which provides reliable communication
User Datagram Protocol (UDP), which provides faster but less reliable communication.
Protocols within the network (layer 3)
IP (both IPv4 and IPv6)
Internet Control Message Protocol (ICMP)
Internet Group Management Protocol (IGMP
Protocols within the datalink (layer 2)
Ethernet and Wi-Fi.
Describe the sender’s side VS receiver’s side in the application layer (layer 7)
Sender – The email client creates the email, including the recipient’s email address, subject, and message body.
Receiver – The email client receives the email and displays it to the user.
Protocols within the physical layer (layer 1)
Ethernet, Wi-Fi, and Bluetooth
Describe the sender’s side VS receiver’s side in the presentation layer (layer 6)
Sender – The email content is converted into a standard format (e.g., MIME) and encrypted if necessary.
Receiver – The email content is decrypted (if necessary) and converted back into a readable format for the email client.
Describe the sender’s side VS receiver’s side in the session layer (layer 5)
Sender – A session is established between the sender’s email client and the email server.
Receiver – A session is established between the receiver’s email client and the email server.
Describe the sender’s side VS receiver’s side in the transport layer (layer 4)
Sender – The email is divided into data packets, and a reliable connection is established using TCP to ensure error-free transmission.
Receiver – The data packets are reassembled and checked for errors using the TCP connection.
Describe the sender’s side VS receiver’s side in the network layer (layer 3)
Sender – The email server’s IP address is determined, and the data packets are routed through the network to the destination.
Receiver – The data packets are received & the IP address is checked to be sure its reach the correct device.
Describe the sender’s side VS receiver’s side in the datalink layer (layer 2)
Sender – Data packets are converted into frames with error checking and flow control information.
Receiver – Frames are received, checked for errors, and converted back into data packets.
Describe the sender’s side VS receiver’s side in the physical layer (layer 1)
Sender – Frames are converted into bits and transmitted over the physical medium (e.g., Ethernet cable or Wi-Fi).
Receiver – Bits are received and converted back into frames to be processed up the OSI model layers.
What is the order of the OSI
7- Application
6-presentation
5- session
4- transport
3- network
2- datalink
1- physical
