EXAM EASY Flashcards
Describe OSI Layer 1
Number: 1
Data format: Bits
Layer: Physical
Media, Signal and Binary Transmissions
Describe OSI Layer 2
Layer: 2
Data: Frames
Layer: Data Link
MAC and LLC
(Physical Addressing)
Describe OSI Layer 3
Layer: 3
Data: Packets
Layer: Network
Path Determination and IP (Logical Addressing)
Describe OSI Layer 4
Layer: 4
Data: Segments
Layer: Transport
End-to-End Connections and Reliability
Describe OSI Layer 5
Layer: 5
Data: Data
Layer: Session
Interhost communication
Describe OSI Layer 6
Layer: 6
Data: Data
Layer: Presentation
Data Representation and Encryption
Describe OSI Layer 7
Layer: 7
Data: Data
Layer: Application
Network process to application
Describe bandwidth
The amount of data that can be transmitter over a network cable at one time, usually expressed in M/G/TBps.
1,000,000 MBps = 1,000 GBps = 1 TBps
More frequencies carried = more data transmitted = higher bandwidth
Describe Baseband
DIGITAL SIGNALLING
Signalling method that uses High and Low voltages on a cable to indicate Binary 1’s and 0’s
Time Division Multiplexing allows multiple data streams
Describe Broadband
ANALOGUE SIGNALLING
Modulates data into frequencies before sending across medium
Describe Attenuation
Gradual weakening of signal as it passed through wire/medium.
The greater the distance or frequency, the more attenuation occurs
Describe Repeaters
Reduce noise of cable, increase signal strength allowing further communication, but add delay
Describe Bridges
Connect two or more network segments - monitors MAC addresses, filters out unneeded packets, thus reducing traffic
Describe Routers
Like Bridges
Connect 2 or more networks and send packets to correct destinations.
Work on Network Layer (3) using IP address not MAC
Describe Gateways
Connect network segments via translation, operate at layers 4-7, often virtual
Describe Star physical topology
Search node connected with it’s own cable, typically UTP, to a central hub, which internally connects them all
Describe Bus physical topology
A single cable (backbone) supports entire network segment, nodes attached at various points
Describe Ring physical topology
Nodes connected in a circle, nodes pass messages from upstream to downstream, acting as a repeater.
Compare and Contrast UTP/STP, Coax and Fibre
UTP: Low cost, low bandwidth, vulnerable to snooping and EMI, 100m range
STP: Med cost, low bandwidth, resistant to snooping and EMI, 100m range
Coax: High cost, med bandwidth, resistant to snooping and EMI, 200-500m range
Fibre: High cost, high bandwidth, invulnerable to snooping and EMI, 1000+km range
Advantages/Disadvantages of UTP/STP/Coax/Fibre
UTP Adv: cheap
UTP Dis: vulnerable to interference
STP Adv: Shielded from interference/cross talk
STP Dis: expensive, heavier, special connectors req
Coax Adv: very resistant to EMI
Coax Dis: rare today
Fibre Adv: invulnerable to EMI/crosstalk, best bandwidth
Fibre Dis: expensive, difficult to install, fragile, special connectors
Describe Circuit Switching
Continuous physical link until ended, clear but inefficient
Describe message switching
Duplicates of signed message sent via different route - slow but reliable
Describe packet switching
Message broken into small packets and sent via different routes over network, fast and efficient
Describe and draw VLANS
Virtual Local Area Networks - virtually separate networks on same cables = reduced traffic, increased security
Class A IP
First 8 bits ID network
Last 16 bits ID machine
126.255.255.255
Class B IP
First 16 bits ID Network
Last 16 bits ID Machine
191.255.255.255
Class C IP
First 24 bits ID Network
Last 8 bits ID Machine
233.255.255.255
Example of a private IP address
192.168.10.0
What parameters does the firewall check?
Packet source
Destination address
Protocol
Port Number
