Networks (Week 10) Flashcards
What do Communication Systems do?
Transmit information from a source to a destination, typically over a network.
Networks can use either analog signals (e.g. old fashioned telephone) or digital signals (e.g. Wi-Fi).
At the source: convert information into a representation that can be transmitted over the chosen network
At the destination: convert signal back into the original representation
What is an example of an conversion for Communication Systems??
Well known example for such a conversion is Morse code.
Developed in the 1830s for telegraph communication
Every letter is encoded by a sequence of short and long signals (e.g. light or sound)
What is Bandwidth?
Bandwidth is about how fast a network can transmit data. If the bandwidth is large enough, data flows smoothly. If the bandwidth is constricted, data flow can halt or stutter.
How is Bandwidth measured?
The speed at which data can be transmitted (per direction) Bandwidth is measured in bits per second: kbps, Mbps, Gbps, Tbps
Kbps – kilobits per second
Mbps – Megabits per second (a megabit is over 1000x faster than a kilobit)
Gbps – Gigabits per second
Tbps – Terabits per second (fiber optic network that carry internet traffic across major expanses such as oceans or continents)
What is Latency or Delay?
How long does it take one particular chunk of information to get from the source to the destination?
What is Ping Time?
A term related to Latency or Delay.
Ping time is the time it takes for a packet of data to go from a device, to a server, and back to the device. This time is measured in milliseconds. A high ping means longer lag time.
In terms of online gaming, lower ping means smoother gameplay.
What is Jitter?
The variability of the delay in a system (high jitter degrades quality in transmissions involving live speech or live video).
Jitter is caused by the disruption of the normal sequence sending data sets or packets. Measured in milliseconds (ms)
What is Range?
Geographical size a network can cover depending on a given technology.
Local Area Networks can span several metres (LAN)
Metropolitan Area Network (MAN) can span over 50kms.
What are some Network Types?
Network types may be based on geographical size:
- WAN – wide area network, e.g. landline telephone system
- MAN – metropolitan area network, e.g. city fibre network
- LAN – Local area network, e.g. Camosun Campus Wi-Fi Network
- PAN – personal area network, e.g. smartphone connected to headphones via Bluetooth
What is the difference between Wired and Wireless Networks?
Wired networks require physical connections with different types of cables, typically containing electrical conductors
Wireless networks use radio frequency signals (electromagnetic waves) to transmit information
What is Broadcast?
Broadcast (one-to-many)
- Radio, TV, CB radio => one sender and multiple receivers are a desired
feature of the network type - Ethernet (both Wi-Fi and wired) => multiple receivers are an unwanted side effect (in most cases)
- In many usage scenarios, there is a need to consider security measures (e.g. to avoid eavesdropping)
What are some Network Types? (regarding how many receivers)
Unicast (one-to-one)
Multicast (one-to-many)
Broadcast (one-to-all)
What is the Point to Point network type?
Point to point (one-to-one)
* Telephone network (typically connects 1 sender and 1 receiver)
* Dedicated channel or line (e.g. for company networks)
What is Ethernet? (part 1)
Ethernet (both Wi-Fi and wired) => multiple receivers are an unwanted side effect (in most cases)
In many usage scenarios, there is a need to consider security measures to avoid eavesdropping
What is Ethernet? (part 2)
Ethernet is the predominant technology for local area networks
Uses a broadcast system (invented back in the 1960s)
* Messages are broadcasted to all connected workstations…
* …but are ignored by all except the destination workstation
Every workstation (WS) has it ́s unique ID – the Media Access Control Address (MAC address) => 12 digit hexadecimal number (48 bit)