Fundamentals of Communications & Networking Flashcards
How do you calculate bit rate?
Baud rate x Number of bits per second
What is baud rate?
The number of signal changes in the medium per second
What is bit rate?
Number of bits transmitted over the medium per second
What is bandwidth?
The range of frequencies a communication range is capable of transmitting
What is the relationship between bandwidth and bit rate?
Direct relationship (directly proportional - straight line through the origin graphically)
What is latency?
The difference between an action being initiated and its effect being noticed
What is a protocol?
A set of rules relating to communication between devices.
What is serial data transmission?
Data being sent one bit at a time over one communication line.
What is serial data transmission used for?
Transmitting data medium/long distances (peripherals to computer)
What is parallel data transmission?
Numerous parallel communication lines send multiple bits between components simultaneously.
What is a skew?
(Parallel) Each medium of a communication line has different electrical properties - bits sent together may not be received together.
What is crosstalk?
(Parallel) Signals from one line can leak into another - data corruption is caused.
Serial advantages?
No skew, no crosstalk, cheaper to install, more reliable (long distances)
What is Synchronous transmission?
When the clock signal is shared between sender & receiver and times when signals are sent. Signals are sent in regular intervals and in the same order they’re sent.
What is asynchronous transmission?
No shared clock signals, you instead use start and stop bits to indicate the duration of a transmission
What are the requirements for asynchronous transmissions?
Same baud rate and synchronising their clocks (for the duration of data transmission)
What does a start bit do?
Starts the receiver clock ticking and synchronises the receiver clock to the transmitter clock.
What does the stop bit do?
Provides time for the receiver to process the received data and allows next start bit to be recognised
Physical star network advantages?
- Easy to add and remove clients from the network
- Eliminates the possibility of collisions
- Failure of 1 cable doesn’t effect network performance
- Packets sent directly to recipient
Physical star network disadvantages?
- Expensive to install due to cabling
- If hub fails, all network communication is stopped
Physical bus topology advantages
- No central hub which reduces chances of network failure
- Cheaper to install as less wiring
- Cheaper installation costs
Physical bus topology disadvantages
Client-Server Networking - what is it?
One/more servers provide services to clients
Serverd are more powerful machines
How do clients get resources and services in a client server network?
What services can be provided?
Request services from the servers which then respond to the client with the requested service.
Emails, user accounts, print queues