B3 - Transmission Flashcards
What is TCP/IP
Transmission Control Protocol and Internet Protocol are used together as the basic communication language of the internet
Data sent over the internet is broken up into ‘packets’ to enable it to be sent more efficiently. Each packet is sent individually and then reassembled at destination
- TCP is used to create packets and reassemble at the end
- IP is used to route packets to the intended computer using IP
12 steps of TCP/IP communication
- Transmission Control Protocol
- Internet Protocol
- Application –> Transport –> Internet –> Network
- Web browser
- HTTP and SMTP
- HTTP: Websites, SMTP: Checking emails
- TCP and UDP
- UDP
- Through the use of ports
- It gives instructions on how to reconstruct the data packet into the correct order
- IP address
- Packet switching
3 Web Protocols
⚫ HTTP - the HyperText Transfer Protocol is used to allow web servers and browsers to transfer files over the internet. it is how we access WWW
⚫ HTTPS - the secure version of the standers HTTP. it uses public key cryptography to encrypt communications between a web browser and server
⚫ FTP - The File Transfer Protocol is used to transfer files over the network. It is the technology used to upload files to a server as well as to download large files
How does HTTPS keep data secure during transmissions
⚫ It incorporates/uses Transport Layer Security protocol (TLS), (allow SSL) (1) which provides extra layers of protection/encryption (1)
⚫ When a browser connects to a site, it checks that the site’s (TSL/SSL) certificate is valid (1) if the site fails the check the browser displays a warning / alerting the user that the site is not secure (1)
⚫ When a browser connects to a site it asks for a public key (1) it uses the public key to produce a session/new key for the connection (1)
⚫ The browser/client negotiates keys with the server (1) creating a shared (symmetric) key for the connection (1)
3 Email Protocols
⚫ POP3 - the Post Office Protocol 3 is used to retrieve emails from the mail server. It allows us to download messages to our client software for office reading
⚫ IMAP (Internet Message Access Protocol) - used for receiving emails/ incoming emails (1) stores emails on server (1) allowing access from multiple devices/synchronises email across devices (1)
⚫ SMTP (Simple Mail Transfer Protocol) – manages outgoing emails / used for sending emails (1) from server to server (1) until it reaches its recipients (mail) server (1)
3 Voice and Video Call Protocols
⚫ RTP - the Real-Time Transport protocol is designed to transfer audio and video over IP-based networks
⚫ H.323 - this was one of the first successful VOIP protocols and is recommended by the ITU it defines the rules for communication audio and video packet switched networks
⚫ SIP - the Session Initiation protocol is used to create, control and end VOIP connections
what is Codecs
- A Codecs is a program used to compress and decompress video and audio files this reduces the space they take up on a adisk and allows fast transfer over a network, such as the internet for VOIP calls and online streaming.
- this leads to a loss of quality in the video or audio
Use of Codecs when VoIP
Uses algorithms (1)
The codec digitises an analogue signal/ encodes (1)
This is compressed (1)
Splits into internet packets (1)
These are transmitted/transferred (1)
When received they are uncompressed (1)
Decodes (1)
User and receiver need to have the same codec (1)
Determines quality (1)
Encrypting for security (1)
Implications of Codecs, using video in digital format
⚫ Codec is a file/piece of software (1)
⚫ Codec is needed to view the video (1)
⚫ Video files are very large (1)
⚫ Codec reduce the size/compress the video file (1)
⚫ Will improve viewing when using a slow connection/ bandwidth (1)
⚫ Affects the quality of the video (1)
⚫ (Lossy) codec save larger amounts of space compared to (lossless) (1)
⚫ Software compatibility (1)
Security Protocols
⚫ Networks must have protocols (or rules) in place for security. These are needed in order to maintain the integrity and security of the data being transferred – it usually does this by encrypting the data using cryptography.
⚫ 𝐒𝐒𝐋 (Secure Sockets Layers) and 𝐓𝐋𝐒 (Transport Layer Security)
are used to ensure that transactions over networks are kept safe
what is Lossy Compression
- Lossy Compression reduces the size of a file but it does this by losing some of the information;
- When compressed files are decompressed they do not give back the original data, because data was lost during compression;
- Because Lossy Compression cannot be decompressed to yield the exact original data, it is not a good method of compression for critical data, such as textual data, we would use Lossless Compression for this;
- Lossy Compression is most useful for digitally sampled analogue data, such as sound, video, graphics or images;
- Some examples of Lossy Compression algorithms are JPEG, MPEG, and MP3.
what is bandwidth and Latency
𝐁𝐚𝐧𝐝𝐰𝐢𝐝𝐭𝐡
- Amount of data transferred/transmitted (1)
- (From one point to another) in a period of time (1)
- Measured in mega/bits per second (1)
𝐋𝐚𝐭𝐞𝐧𝐜𝐲
- Time delay / lag experienced (1)
- Before a component responds to an instruction (1)
- Measured in milliseconds (1)
Implications of Bandwidth and Latency
- Browsing the internet doesn’t need an instant response so latency isn’t a big factor. Bandwidth is an important factor as it affects how long files takes to download
-Online gaming needs very low latency as players need a fast response for real-time updates of character movement
-video calls need low latency and high bandwidth as you need to transfer a lot of data
Factors that affect Bandwidth & Latency
⚫ 𝐀𝐦𝐨𝐮𝐧𝐭 𝐨𝐟 𝐜𝐨𝐧𝐭𝐞𝐧𝐭𝐢𝐨𝐧 / 𝐧𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐨𝐭𝐡𝐞𝐫 𝐮𝐬𝐞𝐫𝐬 (𝟏)
Bandwidth:
At peak times such as early morning when many users are logging on to check emails (1)
Latency:
Network devices may have to queue users/resend packets due to collisions/may not be able to respond to all the connection requests (1)
⚫ 𝐀𝐦𝐨𝐮𝐧𝐭 𝐨𝐟 𝐝𝐚𝐭𝐚 𝐛𝐞𝐢𝐧𝐠 𝐭𝐫𝐚𝐧𝐬𝐦𝐢𝐭𝐭𝐞𝐝 𝐨𝐧 𝐭𝐡𝐞 𝐧𝐞𝐭𝐰𝐨𝐫𝐤 (𝟏)
Bandwidth:
More users simultaneously transmitting data will be ‘sharing’ the connection (1)
Latency:
Network devices may have to resend packets due to collisions/ receiving devices may take longer to process extra requests (1)
⚫ 𝐓𝐲𝐩𝐞 𝐨𝐟 𝐜𝐨𝐧𝐧𝐞𝐜𝐭𝐢𝐨𝐧 𝐛𝐞𝐢𝐧𝐠 𝐮𝐬𝐞𝐝 (𝟏)
Bandwidth:
Eg, a wired connection (is generally faster) generally has a higher bandwidth than wireless connection (1)
Latency:
Some connection types require transmissions. e.g., Wi-Fi neds cable - wireless - cable. These changes take time. (1)
⚫ 𝐃𝐢𝐬𝐭𝐚𝐧𝐜𝐞 𝐟𝐫𝐨𝐦 𝐭𝐡𝐞 𝐧𝐞𝐚𝐫𝐞𝐬𝐭 𝐭𝐞𝐥𝐞𝐜𝐨𝐦𝐦𝐮𝐧𝐢𝐜𝐚𝐭𝐢𝐨𝐧 𝐞𝐱𝐜𝐡𝐚𝐧𝐠𝐞 / 𝐧𝐞𝐭𝐰𝐨𝐫𝐤 𝐥𝐢𝐧𝐤 (𝟏)
Bandwidth:
Bandwidth reduces over distance / gets weaker (1)
Latency:
Signal takes longer to cover a greater distance and must travel at least as far as the nearest network (1)
Security considerations:
What can we put in place to minimize security risks?
⚫ User authentication - usernames and passwords authenticate users who have permission to use a network and prevent unauthorized access by hackers
⚫ Firewalls - these monitor traffic to prevent unauthorized access and dangerous data packets being passed into the systems and causing harm
⚫ Encryption - information can be intercepted while being transmitted using encryption ensures intercepted data cannot be read. HTTPS is a commonly used method for secure data transmission
