2.1 - data transmission types + methods 📤 Flashcards
how is a data packet structured?
a header w/ the IP addresses of both sides, the sequence number for ease of assembly at the destination, and the packet size in bytes + a payload w/ the actual data being sent in the packet + a trailer that helps identify the packet’s end and also checks for data errors
how can a network for transmitting data packets be visualized?
by placing the sending device + router to the left, the receiving device + router to the right, and the router nodes in between w/ lines connecting all of them for the possible routes
how does packet switching work?
it involves files being decomposed on the sending side into numerous data packets that can then be transmitted independently from each other and reassembled into a single file when they reach the receiving side
how can packet switching be a good thing?
it’s possible to reroute data packets in the event of unavailable transmission lines and data can also be transmitted in this way at higher speeds
what problems can packet switching cause?
data packets may need to be sent again in case they get lost on the way - packet reordering can also induce delays on the receiving side
how can data packets overcome clogged transmission lines caused by excessive packet losses? (out syl)
by having numbers hopped onto their headers that’re reduced by 1 upon moving onto another router (eg. hop number of 9 at router A -> reduced to 8 on the way to router B -> further reduced to 7 on the way to router C -> and so on)
what happens when the hop number of a packet becomes zero? (out syl)
it gets deleted at the next router it reaches and the receiving side asks for the sender to resend any missing packets
name the three modes data transmission can occur in w/ their directions:
simplex (unidirectional), half-duplex (semi-bidirectional), and full-duplex (fully bidirectional)
name the two transmission types data can be sent using w/ how many bits they send at a time:
serial (multiple bits are sent individually) and parallel (multiple bits are sent simultaneously)
what traits does serial transmission have?
it can be relied on for low-interference transmission over longer distances, its lower speed makes it best for smaller files like readmes and vector symbols, it requires less hardware than parallel transmission, and all bits arrive at the receiving side perfectly in sync
what traits does parallel transmission have?
it’s faster than serial transmission (making it better for larger files like executables as well as more time-sensitive data) and allows for easier I/O operation programming but can result in some bits arriving out of sync at the receiving end and is also expensive due to the increased hardware requirements
how does a typical USB cable look like?
it’s shielded on the outside to insulate the four wires it contains (red wire - 5V, white wire - data+, green wire - data-, black wire, ground wire)
what happens when you plug a USB into a device?
the data wires slightly change in voltage to make the device recognize the USB and check if any of the already-installed drivers are appropriate for it
how many USB connector types are there?
type A (1.x to 3.x), type B (ditto), and type C (2.x onwards)
are all USB versions backwards-compatible?
yes
