Digital Systems Networking

Networking History 50s-60s

• Computers have been linked together to exchange information since the late 1950’s

• Networking as you would be more familiar with it came around the mid 1960’s, when packet-switching was introduced.

• ARPANET (what developed into the internet) started in 1969 in the USA

Networking History 70s

Ethernet, the basis of most modern networking standards was developed in 1973-1979

• 1973: It began designing TCP/IP, the protocol that powers the internet

• 1974: First use of the term "Internet" as a shorthand for "internetworking“

• 1976: First email sent across ARPANET

• 1978: TCP/IP protocols were completed

Networking History 80s-90s

Dial-up networking was popular with consumers 1980’s-late 1990’s

1980s: Birth of the Modern Internet

• 1983: ARPANET switched to TCP/IP, making it the official standard for internet communication

• 1984: DNS (Domain Name System) was introduced - replacing numeric IP addresses with human-readable names (e.g., google.com)

• 1989: the World Wide Web (www) has been proposed

1990s: Public Internet

• 1990: ARPANET was decommissioned.

• 1991: The World Wide Web (www) was made public.

• 1993: First graphical web browser (Mosaic) released.

• 1995: Internet commercialised, explosion of websites and email usage

Networking History 00s-current

2000s - Present: Broadband, Mobile, Cloud, IoT

• 2000s: Widespread broadband, Wi-Fi, and VoIP (e.g., Skype).

• 2007: iPhone launched, beginning of the mobile internet era.

• 2010s: Rise of cloud computing, streaming, social media, and IoT.

• 2020s: Focus on 5G, edge computing, IPv6, and cybersecurity

Wifi & Mobile data are perhaps the dominant consumer method today

Networking Hardware

• Needed to physically interact with the computer

• Some use cables, so those cards have socket to plug in and sent the appropriate electrical or optical signals

• Some are wireless, so the cards have a radio and antenna to transmit signals

Dial-Up Internet

used normal phone lines and a modem to convert the digital signal to an analogue signal that could be carried by the phone line

phone lines only support a narrow range of signal (since human voice only uses up about 4-8kHz frequency range, so a modem needs to map the signals to this limit

bandwidth was limited to a maximum of 56 kbps (kilobits)

Modems

a portmanteau of modulator-demodulator, which is the technical name for encoding and decoding the signal to/from analogue

Host

a computer on the network

to send things on a network you need to be a host on it

IP Address (Internet Protocol)

a unique numerical identifier assigned to each device connected to a computer network that uses the IP for communication

hosts are assigned 1 (or occasionally more)

either IPv4 addresses like 10.61.172.54

or IPv6 addresses like 2001:ac:0:8bb:0:135:6:1

Port

used as well as IP address

allow multiple network programs to be running at one time

just a number, 0..65536 (ie, 16 bits)

for major protocols, the port number is documented and “well-known” but there is no enforcement

Host, Port Pair

used to identify the source and destination of traffic

Network Protocol

established set of rules that determine how data is transmitted between different devices in the same network

allows connected devices to communicate with each other, regardless of any differences in their internal processes, structure or design

Why are Network Protocols Important?

ensure reliable and accurate communication between different devices (even if they’re from different manufacturers)

standardisation - create a common language for devices

help with error handling, data compression, encryption, and speed management

enable the internet to work globally

Common Protocol Examples

Protocol	Purpose	Real-Life Example
HTTP (HyperText Transfer Protocol)	Used for browsing the web	Loading a website in chrome
TCP (Transmission Control Protocol)	Ensures reliable delivery of data	Sending an email
IP (Internet Protocol)	Handles addressing and routing	Your IP address identifies your device
FTP (File Transfer Protocol)	Tansfers files between computers	Uploading to a web server
SMTP (Simple Mail Transfer Protocol)	Sends emails	Gmail uses this to send messages
DNS (Domian Name System)	Translates domain names to IP addresses	Turns "google.com" into 142.250.74.14

TCP vs UDP (Transmission Control Protocol vs User Datagram Protocol)

Feature	TCP	UDP
Connection	Connection-oriented (establishes a session)	Connectionless (no session setup)
Reliability	Reliable - ensures data is received	Unreliable - no guarantee of delivery
Error Checking	Yes - with acknowledgements and retransmission	Yes - but no retransmission
Speed	Slower (due to overhead for reliability)	Faster (no delay for handshakes or ACKs)
Ordering	Guarantees data arrives in order	No order guarantee
Examples	Web browsing (HTTP/HTTPS), email (SMTP), file transfer (FTP)	Streaming (video/audio), gaming, VoIP

both transport layer protocols used for sending data over networks

Network Architectures

There are two common network architectures used for communication and data exchange between devices in a network.

• Client-Server

• Peer-to-Peer (P2P)

Client-Server

one device (the server) provides services, data or resources, and other devices (the clients) request or access these services

Server

a powerful computer or system that stores and manages data, provides services, and responds to client requests

can handle multiple client requests simultaneously

Client

device/application that sends requests to the server for resources or services

Advantages of Client-Server

centralised management and control - easy to update and secure

scalability and maintenance are easier, especially with multiple clients

Disadvantages of Client-Server

server overload or failure can disrupt service for all clients

requires more infrastructure and resources to manage the server

Peer-to-Peer (P2P)

each device (peer) can act as both a client and a server, sharing resources, files, or services directly with other peers without a central server

Peers

devices or nodes that communicate directly with each other

each one has the capability to request and provide resources or services

Advantages of P2P

decentralised - no central server to fail

scalability as each peer adds more resources to the network

can be more efficient in terms of resource distribution

Disadvantages of P2P

security and privacy can be harder to manage

can be inefficient for some applications if peers are unreliable or inconsistent

Client-Server vs P2P

Both models are suited for different use cases depending on the required performance, control, and resources

Feature	Client-Server	P2P
Centralisation	Yes (server)	No
Resource Management	Server	Peers share equally
Scalability	Can become bottleneck if too many clients	Scale better as more peers join

Network Bandwidth

the maximum amount of data that can be transmitted across a network in a specific amount of time

typically measured in bits per second (bps), or megabits per second (Mbps)

Why is Network Bandwidth Important?

higher = faster downloads/uploads, smoother video streaming, and better performance for multiple users/devices

Bandwidth

how much data can flow at once, not how fast it travels

Bandwidth Contention in Networked Systems

mesh of interconnected routers

Why Bandwidth Contention?

when multiple processes, devices, or users compete for limited network bandwidth

Causes of Bandwidth Contention

• high network traffic

• limited available bandwidth

• congested network paths

Impact of Bandwidth Contention

• increased latency

• slower download/upload speeds

• buffering in video or audio streams

• dropped packets or failed transmissions