Unit 1.5 - Network topologies, protocols and layers Flashcards
Topology
Diagram showing the Layout of connections in a network
Features - Star Topology
Computers connected to a
central switch in a LAN
Advantages - Star Topology
Reliable
No Data Collisions
High Performance
Easy to Add/Remove Nodes
Disadvantages - Star Topology
Expensive - Cables
Extra Hardware - Switches
Server/Switch Fails - connected nodes fail
Features - Mesh Topology
Switches/Routers connected so more than one possible route
Advantages - Mesh Topology
Reliable & Self-Healing
High Performance- Data sent same time, No Collisions, High Traffic
No Central Node
Disadvantages - Mesh Topology
Expensive & Difficult - Cables
Redundant Connections
Uses - Mesh Topology
Cluster of Surveillance Drones
Military Communications
Smart Devices around the home
Features - Ring Topology
Device connect to two others in ring. Data Travels in one Direction
Advantages - Ring Topology
No Data Collisions
Disadvantages - Ring Topology
Cable/Device fail - Network fail
Low Performance
Features - Bus Topology
One Main cable.
Terminators - stop signals reflecting back
Advantages - Bus Topology
Easy to install
Low Cost - Cable
Disadvantages - Bus Topology
Cable fail - Network fail
Data Collisions
Low Performance
Security Risks - All devices see all data
Wi-Fi
Wireless connection to Network
Requires a WAP / Router.
Data sent on specific frequency called a channel
Advantages - Wi-Fi
Convenient & Low Cost
No Cables - Wander around
Add/Remove Devices easily
Less Disruption to Building/Walls
Disadvantages - Wi-Fi
Interference & Signal quality
Less Secure - Hacking
Lower Bandwidth than wired
Wi-Fi - Frequency
2.4 Ghz
5 Ghz
Features - 2.4 Ghz
Long range
Slow data transmission
(450 Mbps or 600 Mbps)
Interference from Cordless phones, baby monitors
Features - 5 Ghz
Short range
Fast data transmission
(1300 Mbps)
Wi-Fi - Channels
Channels 1 - 11
Used for Radio Wave Communication
Interference
Cordless phones, baby monitors.
Wi-Fi - Encryption
Data is Scrambled
during communication
Protect from Hackers, unreadable if intercepted.
Recipient needs Key to decode
Wi-Fi - Protocols
Set of rules for how computers communicate (send/receive data)
Speed of transmission, size of the message, error checking, transmission
TCP/IP
Transmission Control Protocol/Internet Protocol
TCP Provides Error Free Transmission Separates & Reassembles data packets
IP routes packet across a WAN giving the packet its destination address.
HTTP
Hyper-Text Transfer Protocol
Allows the browser to communicate with a web server to request and deliver HTML Web Pages
HTTPS
Hyper-Text Transfer Protocol Secure
Encrypts connection/data
FTP
File Transfer Protocol
Transmit files between client & server
POP
Post Office Protocol
Allows Email Clients to retrieve and delete email from an email server
IMAP
Internet Message Access Protocol
Allows Email Clients to retrieve email from an email server (not deleted).
SMTP
Simple Mail Transfer Protocol
Send emails to Email Server
Layers
Reduces the complexity of networking into smaller manageable sub-problems
Layers - Application (7)
APPLICATION you are using
Layers - Presentation (6)
ENCRYPT / FORMATS / TRANSLATE / COMPRESS
the data
Layers - Session (5)
CONNECTIONS are established, managed, and torn down
when communicating on a LAN (Same network)
Layers - Transport (4)
CREATING, SEQUENCING, ERROR CHECKING packets
When communicating on a WAN (Different networks).
Layers - Network (3)
ROUTING PACKETS on a WAN (Different networks)
Layers - Data Link (2)
CREATING, ROUTING, ERROR CHECKING frames
When communicating on a LAN (Same networks)
Layers - Physical (1)
DATA ENCODING bits (0/1).
Data Packet
A unit of data transmitted across a network.
TCP splits Large Files down into small packets
Data Packet - Header
Contains: IP address Packet number Length of packet Protocol used
Data Packet - Payload
Contains:
The Data
Data Packet - Trailer
Contains:
End-of-packet marker
Error checking (Check sum)
Packet Switching - Frame
Unit of data transmitted between two locations on LAN
Packet Switching
Sending data packets across a network.
Each packet finds its own route and reassembled at destination
Circuit Switching
Link is established first Packets sent in a stream along the established connection until received
Data Collisions
2 devices transmit data
on the same network
at the same time
down the same connection
Packet Sniffing
Captures a copy of
packets of data for
reading / analyzing
