Data Transmission Protocols (Email (SMTP (Simple Mail Transfer Protocol,…
Data Transmission Protocols
Simple Mail Transfer Protocol
Also used to transmit the data between email servers so that it can move from your outgoing mail server to the recipients mail server
Used to transmit data from your email client to your outgoing mail server.
SMTP will then use the recipients email domain to identify their SMTP server and establishes a connection to this server. It then will forward the email to their server ready for the recipient to access it.
Post Office Prorocol
Used to download emails from your mail server to your email client
With POP3 a connection is established between the recipients email client and their mail server. Then emails are downloaded to the email client and removed from the mail server.
This has the drawback that you won’t be able to access your emails on multiple devices.
Internet Message Access Protocol
The Internet Message Access Protocol is an alternative to POP3 for retrieving emails from your mail server.
Same way as POP3 but with the key difference that instead of downloading your emails, they are synced between your client and your server.
This means you will be able to access the same emails on multiple devices, and any change made on one device (such as filing an email in a folder) will be updated on all other devices.
Session Initiation Protocol
This is a signalling protocol that establishes the connection between sender & receiver.
We use SIP to establish the location (IP addresses) of the people taking part in the conversation & to agree on the CODECS used for encoding and decoding the voice & video to be transmitted.
A SIP signalling packet is sent from the person establishing the VoIP call to the intended recipient.
When the SIP packet is received, this is where the recipients VoIP phone starts to ring.
Real-Time Transport Protocol
RTP works alongside SIP
While SIP is used to establish the connection, RTP will actually transmit the data packets along that connection.
RTP is a protocol built upon the User Datagram Protocol (UDP) which is a more general data transfer protocol that is an alternative to TCP.
RTP is built upon UDP because it gives no guarantee for delivery, taking no responsibility for recovering lost packets.
RTP Control Protocol
RTCP is a sister protocol to the Real-Time Transmission Protocol. The RTCPs primary function is to send control packets that provide feedback on the quality of the data delivery.
This includes information like bytes sent, packet counts, jitter and round-trip times. This might be used, for example, to decided to change the CODEC being used to improve performance.
HyperText Transfer Protocol
HTTP establishes a connection between the client and server and then transfers web pages to the client so they can be rendered by the browser.
It also allows the transfer of additional related files, such as images embedded within the page.
When you type a URL into your web browser and press return, a HTTP message will be created that requests for a file from the web server that the URL points to. The server will then send an HTTP response message that contains the file we requested.
The HyperText Transfer Protocol Secure is a version of HTTP that transmits data in a secure encrypted format using either TLS or SSL technologies.
It resolves the major issue of HTTP which is it’s lack of security. We’ll learn more about this in the next lesson.
File Transfer Protocol
This used when transferring files between computers over the internet. This isn’t specific to web pages, however it is the common protocol used when uploading web pages to a web server so they can be accessed by users browsing the web.
Using a web servers FTP address, username and password, FTP can establish a connection between a clients computer and the server.
This first connection is called the control connection. Once this is established a second connection is established called the data connection.
Secure Payment Systems
The 3D Secure protocol is the popular method for secure online payments used by VISA, MasterCard, American Express and most others. It is an XML protocol that uses SSL encryption to ensure data is secure.
During a purchase process, when a user submits their card details for payment, the merchant website will establish if the card is enrolled on 3D secure.
If so, the buyer will be directed to a 3D secure page for their own bank to authenticate the buyer. This successful authentication is forwarded to the merchant website who can then send the buyers card details and the 3D secure authentication to their own bank to authorise the payment.
Secure Electronic Transaction protocol
This is a communications protocol that was initially supported by MasterCard & VISA for secure payments. It did not gain much popularity though and isn’t in heavy use.
With SET, when a purchase process is started only the purchase order is sent to the merchant website, the card details instead go to the merchants bank. This will then authorise the payment with the purchasers bank and the authorisation is returned to the merchant website to complete the transaction.