3.1.2 Protocols 1 OSI Flashcards
Need for communication protocols
Networks made up of dissimilar devices must all agree to the same set of rules for data to be transferred between devices.
BCS definition
A standard set of rules to ensure proper transfer of data between devices. Can specify the format of the data and what signals are used to start control and end data transfer.
Rules for
Error checking Authentication Signaling How data is packaged Joe addressing works in a network.
OSI benefits
Purpose to Make sure different manufactures can be sure their products will be able to connect with existing systems.
Consumers can be sure that HW or SW from any country will work together in communicating successfully.
Process of network communication involves
Transmitted data going through series of protocols in order 7-1
Then
Receiving same data going through protocols in order 1-7
OSI definition
Consists of a specific set of protocols.
Seven layers.
Each layer deals with specific functionality.
Control is passed from one layer to the next.
Each layer interacts directly only with the layer immediately beneath it.
OSI layers
Application Presentation Session Transport Network Data Physical
Application
Presenting information in human friendly way
Recurved info from presentation layer
HTTP POP3
Presentation
Preparing info in the correct format for device being used.
Concerned with encryption/ decrypting
Compressing: decompressing info
Session layer
Protocols in this layer Responsible for opening a temporary channel between the application being used and remote server being contacted.
Responsible for authentication
And authorisation
Transport layer TCP
Segmentation
Flow control
Error checking
Protocols that work in transport layer- Transmission Control Protocol and user data gram protocol
Network layer IP addresses
Responsible for
Adding the sending and destination IP address- transmitting
Checking the sending and destination IP address-receiving
Finding best route for data traffic.
Data link layer- Ethernet
Assigns physical addresses MAC address to IP addressed in the packet header for both sender and receiver.
Converts data into binary data- the actual bits sent Transmitting
Reads binary data and converts it from binary into the correct format for the next layer- receiving
Responsible for Detroit errors in binary data
Also responsible for checking is carrier media is free
Physical layer- signalling
Responsible for converting the binary data into the appropriate physical form for the carrier media used.
The reverse is true for receiving the physical signal- converted from pulse of electric/ light/ radio into 1s and 0s
‘No actual protocols are involved
