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1.5- Network Protocols, Topologies & Layers - Coggle Diagram
1.5- Network Protocols, Topologies & Layers
Star Network Topology
All devices in a
star topology
are connected to a central switch or server that controls the network (similar to a client-server network)
Advantages
- easy to add more devices, if one device fails the rest is unaffected, better performance than other setups (few data collisions & all devices can transmit data at once)
Disadvantages
- if the switch has an issue then the rest fails, hardware for a wired star topology is expensive
Mesh Network Topology
All devices in a
mesh topology
are connected to each other without a central switch (similar to a peer-to-peer network)
A
full mesh network topology
is where every device is connected to every other device and a
partial mesh network topology
, is where all devices are somehow connected but every device isn't connected to every other device
Advantages
- (in theory) no node should be isolated, each node can communicate with more than one at once, roughly same connection everywhere
Disadvantages
- lots of maintenance, more interference, less secure, higher cost than other topologies
WiFi
Frequency & Channels
A
channel
is a small range of WiFi frequencies
Wifi mainly uses 2 radio frequency bands to connect devices- 2.4GHz & 5GHz
Each frequency band is split into numbered channels, each of which cover a small frequency range. Where these overlap, there will be interference (more overlapping in 2.4GHz band than 5GHz)
As long as 2 devices are transmitting & receiving on the same channel, they will be able to communicate
Encryption
Data broadcasted on wireless networks must be encrypted to be kept secure
Encryption
is done by scrambling data into cipher using a 'master key'. This same 'master key' is used by the receiving device to decrypt the data
General
WiFi
is a common standard for wireless networks
Advantages
- users can move around freely whilst being connected, easier to set up, less expensive, increased convenience, transfer to social media is easier, can handle lots of users
Disadvantages
- slower than wired networks, relies on signal strength to WAP, signal can be obstructed, less secure than wired networks
Ethernet
Ethernet
is a standard for network technology which is used for communication on a wired LAN
It is a layer 2 standard & ensures reliable, error-free communication
Systems communicating over Ethernet divides data into small pieces called
frames
Each
frame
includes actual data, source & destination MAC addresses and a cyclic redundancy check, used to check for errors
Uses of IP Addressing & MAC Addressing
IP Addressing
Static IP Addresses
don't change but
dynamic IP Addresses
change depending on location
IPv4 was previously used but IPv6 is now being used as we're running out of static IP addresses
An
Internet Protocol
address is a unique string of 4 numbers between 0-255, separated by full stops (dotted decimal notation), used to identify every computer
Used to route packets on WANs
MAC Addressing
A
Media Access Control
address is unique to every device which can communicate with other devices
They are embedded into a device's NIC when manufactured (cannot be changed by owner)
A MAC Address uniquely identifies a device on a network by identifying its the network adapter it uses
They're made of 48 bits and usually written in hexadecimal
Used to route frames on LANs
Concept of Layers
Layers
are used to reduce the complexity of a problem by splitting it into sub-manageable problems
Devices can be manufactured to operate at a particular layer
The layers are as follows:
Layer 4 (Transport Layer)
- includes TCP/IP, error checking of packets, creating & sequencing of packets
Layer 3 (Network Layer)
- includes IP addressing, routing packets on a WAN, TCP/IP
Layer 6 (Presentation Layer)
- includes encryption
Layer 2 (Data Link Layer)
- includes MAC addressing, error checking of frames and creating & routing of packets on LAN
Layer 7 (Application Layer)
- includes HTTP, HTTPS, SMTP, POP, IMAP, FTP, web browser, emailing, file management
Layer 1 (Physical Layer)
- includes MAC addressing, frequency & channels and encoding bits into wires & wireless
Packet Switching
When a file is sent over a TCP/IP network, it is split into packets which travel separately on different routes
They reach (using IP address) and reassemble at the receiving device back into the original file
Each packet contains a packet number, sender's IP address, receiver's IP address, relevant protocol, actual data and error check (checksum number)
Packet switching allows for faster and more secure data transmission
Uses of Protocols
TCP/IP
-
Transmission Control Protocol/Internet Protocol
is made up of 2 protocols, which, when combined, allow communication between devices
TCP
on sending device breaks data into smaller parts (
packets
) so it can be transported.
TCP
on receiving device puts packets back together correctly
IP
is responsible for packet switching
HTTP
-
HyperText Transfer Protocol
is used to control format & transfer of web pages from Internet
HTTPS
-
HyperText Transfer Protocol
is a secure version of
HTTP
(all files sent & received are encrypted)
FTP
-
File Transfer Protocol
is used to send files between computers
POP
-
Post Office Protocol
is used to retrieve emails from a remote mail server
IMAP
-
Internet Message Access Protocol
is an advanced version of POP
SMTP
-
Simple Mail Transfer Protocol
is used to send emails to a mail server
A
protocol
is a set of rules which control communication between devices on a network
