Protocols Flashcards
Protocols
standards/rules used to define how devices communicate. They govern the transmission of data.
Each protocol has its own method to determine:
- How data is formatted when sent
- How the data is compressed
- The size of message and speed of transmission
- How to check for errors in data
Handshaking
the client requests access, the server grants it and the protocols are agreed
Packets
collections of data forming part of a message
Packet switching
- packets are sent individually across a network
- packets from the same message may take different routes according to the availability and traffic conditions
- the packets are assembled to form the complete message at the receiving end.
As well, it improves the reliability of sending messages because if one route is busy, another can be found.
TCP/IP model
- Consists of four layers, with each layer responsible for a small part of the communication process. Referred to as a modular design.
- Advantage - is that each layer of the protocol software can be easily adapted for specific hardware and operating systems
Application layer
Encodes the data being sent so that it will be understood by the recipient.
This means formatting data and adding an appropriate header according to a protocol being used, such as HTTP or FTP.
Transport layer
Splits the data into packets and adds packet information such as, packet number specifying that packet’s order and the total number of packets so they can be reassembled correctly.
Internet layer
Attaches the IP address of the sender so the recipient will know who sent it. It also attaches the address of the host that is sending the data and the destination IP address.
Link layer
Attaches the Media Access Control (MAC) addresses of the sender and the recipient, allowing the packet to be directed to a specific device on a local area network.
At the receiving end, these data packets are passed back up the protocol stack.
Protocols – application layer:
HTTP FTP/SFTP SMTP POP3 SNMP
Hyper Text Transfer Protocol - HTTP
- used to access and receive web pages in the form of HTML files
- protocol requests the web server to transmit the requested web page to the user’s browser for viewing
- HTTPS encrypts
File Transfer Protocol - FTP/SFTP
- Used to transfer files online
- For moving information from the computer you’re working on to the server where the website is hosted
- Can be used to share/upload files. File is uploaded onto the FTP server and link sent to another person
Simple Mail Transfer Protocol – SMTP
- Used for sending email messages
- Needed when using different email service providers
- At least one requirement of this protocol is the specification of an IP port address on which this protocol will ‘listen’ for the messages
- Requires a sender name, receiver name, subject and body
Post Office Protocol - POP3
- Used for receiving emails
- POP receives and holds email on the server until the user picks it up
- User can download all emails from the server to store on their computer
- Creates local copies of emails and deletes the originals from the server, so emails are on the user’s devices