Topic 3 Networks
- Server: A central piece hardware/ computer system/ software application that
provides a service to other computer systems on the same network (centralized
system where data and instructions come from)
- Client: A computer system or software application that requests services from a
server connected to the same network (like a node- something serving a central
system)
Computer network
- A computer network is formed when two or more computers are linked together.
- Every computer or device on a network can send and receive data from any of the
other computers or devices connected to the network
The different ways to connect computer systems:
1. Hub: Connection point for devices on a single network
- When a network wishes to send data to another device on the network it
copies the data and sends it to all devices connected to its ports.
→ This generates a lot of unnecessary traffic on the network, slowing it down.
2. Switch: Similar to a hub, but can identify which device is connected to which port,
allowing a network connected by switches to operate much faster- data is only sent
to the computer that needs it.
3. Router: Can connect multiple networks and serves as an intermediary between
them.
What is the internet?
- Globally connected network system
- Uses TCP/IP protocol to transmit data
- No centralized governance
- Hosts the web pages that make up the world wide web
- It is the Physical infrastructure; the world wide web is the information
- ISPs (internet service provides) run networks to provide internet access + are glued
together by internet exchanges (IXPs).
- IXPs are the key to connecting all the different ISPs and networks together- usually
run and maintained by non profits.
How does the internet work?
- Data travels in the form of packets
- Every file you send or request you make is split up into packets over the internet.
- Individual packets often take different routes through exchanges, ISPs, and junction
boxes.
- Ultimately reach the same destination and are reassembled at destination.
Packet switching
- A packet is a unit of information suitable for travel through computer networks.
- Data is grouped into packets.
- A file being transmitted through packet switching may be divided into multiple
packets and each packet could follow a different route to the same destination.
- This allows for more efficient data transmission and reduced delays.
, - Header contains the sender and destination
- Payload is binary (text file and info)
→ Information is sent from one router to another to each the right server
Router
- It is used to manage traffic
- Controls the flow and checks the address of data packets
- Puts packets on the correct path
- A secure transmission process
★ Different types of networks include:
1. LAN
- connecting different devices together and serving as an interface between
the network and the internet.
- Covers a single building or collection of buildings with a radius of one km or
less.
2. WAN
- Covers more distance than LAN
- Greater than 1 km radius
- Often uses multiple routers.
- Consists of several LANs connected together
- May use leased lines.
Local Area Networks (LAN) Wide Area Network (WAN)
1. Have a small geographical rage and do not 1. Have a large geographical range spreading
need any leased telecommunication lines. across boundaries requiring leased
2. LAN’s have a high data transfer rate. telecommunication lines.
3. If there is a need to set-up a couple extra 2. Have a lower data transfer rate and less speed
devices on the network, it is not very compared to LAn’s
expensive to do that. 3. Since networks in remote areas have to be
4. Tend to have fewer problems associated connected the set-up costs are higher.
with them, as there are smaller numbers of However, WAN’s using public networks can be
systems to deal with. set up very cheaply just using software.
4. WAN’s tend to be less fault tolerant as they
- Server: A central piece hardware/ computer system/ software application that
provides a service to other computer systems on the same network (centralized
system where data and instructions come from)
- Client: A computer system or software application that requests services from a
server connected to the same network (like a node- something serving a central
system)
Computer network
- A computer network is formed when two or more computers are linked together.
- Every computer or device on a network can send and receive data from any of the
other computers or devices connected to the network
The different ways to connect computer systems:
1. Hub: Connection point for devices on a single network
- When a network wishes to send data to another device on the network it
copies the data and sends it to all devices connected to its ports.
→ This generates a lot of unnecessary traffic on the network, slowing it down.
2. Switch: Similar to a hub, but can identify which device is connected to which port,
allowing a network connected by switches to operate much faster- data is only sent
to the computer that needs it.
3. Router: Can connect multiple networks and serves as an intermediary between
them.
What is the internet?
- Globally connected network system
- Uses TCP/IP protocol to transmit data
- No centralized governance
- Hosts the web pages that make up the world wide web
- It is the Physical infrastructure; the world wide web is the information
- ISPs (internet service provides) run networks to provide internet access + are glued
together by internet exchanges (IXPs).
- IXPs are the key to connecting all the different ISPs and networks together- usually
run and maintained by non profits.
How does the internet work?
- Data travels in the form of packets
- Every file you send or request you make is split up into packets over the internet.
- Individual packets often take different routes through exchanges, ISPs, and junction
boxes.
- Ultimately reach the same destination and are reassembled at destination.
Packet switching
- A packet is a unit of information suitable for travel through computer networks.
- Data is grouped into packets.
- A file being transmitted through packet switching may be divided into multiple
packets and each packet could follow a different route to the same destination.
- This allows for more efficient data transmission and reduced delays.
, - Header contains the sender and destination
- Payload is binary (text file and info)
→ Information is sent from one router to another to each the right server
Router
- It is used to manage traffic
- Controls the flow and checks the address of data packets
- Puts packets on the correct path
- A secure transmission process
★ Different types of networks include:
1. LAN
- connecting different devices together and serving as an interface between
the network and the internet.
- Covers a single building or collection of buildings with a radius of one km or
less.
2. WAN
- Covers more distance than LAN
- Greater than 1 km radius
- Often uses multiple routers.
- Consists of several LANs connected together
- May use leased lines.
Local Area Networks (LAN) Wide Area Network (WAN)
1. Have a small geographical rage and do not 1. Have a large geographical range spreading
need any leased telecommunication lines. across boundaries requiring leased
2. LAN’s have a high data transfer rate. telecommunication lines.
3. If there is a need to set-up a couple extra 2. Have a lower data transfer rate and less speed
devices on the network, it is not very compared to LAn’s
expensive to do that. 3. Since networks in remote areas have to be
4. Tend to have fewer problems associated connected the set-up costs are higher.
with them, as there are smaller numbers of However, WAN’s using public networks can be
systems to deal with. set up very cheaply just using software.
4. WAN’s tend to be less fault tolerant as they
