L4 Networking and the Internet Flashcards
Telephone - circuit switching Start of the internet Communication links WWW vs internet LAN WAN How the internet works Packet switches TCP / IP ARPANET Networking Hardware Modem Common Internet Protocols RFC (TCP, IP, HTTP, UDP) 32-bit number, 128-bit number Client & server software Connecting to the internet Internet's backbone Cloud computing IaaS PaaS SaaS Cloud deployment models (public cloud, private, hybrid) Virtualization
When was the telephone invented?
1876: first successful bi-drectional transmission of clear speech by Alexander Bell and Thomas Watson
Who is George Stibitz and what did he do in 1940?
1940: first successful transmission of digital data through telegraph wires by George Stibitz (considered to be the father of modern digital computing).
What did the telegraph do?
The telegraph enabled messages to be sent by using more code, typically over electrical wires.
Morse code was used to transmit messages globally as a counter attack to the alien invaders.
The start/precursor to computing.
Which war did computer technology play an important role in code-breaking?
WW2
When was ARPA (Advanced Research projects Agency) established?
1958
When did construction of ARPANET (packet-switching network)?
April 1969
What is circuit-switching?
If you wanted to call someone, you would phone a telephone operator and ask to be put through to somebody. The operator would physically make the connection on a large plug board (they would pull out a wire and then they would plug it in again, physically making a connection between two telephones.)
Around the 1960s, circuit switching went electronic and switching was performed using relays rather than human operators. It still relied on a physical connection being made between the caller and the receiver.
What is the Internet?
Internet is a computer network that interconnects hundreds of millions of computing devices throughout the world so that everyone can have end to end communication
All the devices that are connected to the internet, they are referred to as hosts or end systems
The devices interconnect with two things, communication links and packet switches
What are communication links?
These are the connections or pathways that facilitate the transfer of data between different devices or nodes in a network, so it can be guided or unguided
Guided is like a physical medium via which the signals are transmitted
- Open wire
- Twisted pair
- Coaxial cable
- Optical fiber
Unguided is technique that allow transmission of electromagnetic waves through a wireless medium/without using any physical medium
- Microwave transmission
- Radio transmission
- Infrared transmission
What is the difference between WWW and the Internet?
The Internet is a global system of Interconnected computer networks.
Carries a vast range of resources and services
WWW is a global collection of documents and other resources accessed through the internet using HTTP - one of many internet communication protocols.
Documents are linked via hyperlinks and are identified by their URL.
What are the different types of networks?
LAN - Local area network
Operates within 1km radius
Client-server or peer-to-peer configuration
Can connect multiple LANs to form an intranet
WAN - Wide Area Network
Distances over 1km
The internet
Network of networks that use the TCP/IP
What is packet switches?
A route or a path is defined as a sequence of communication links and packet switches traversed by a packet from the sender to the receiver
(A route or a path mean the same thing they are interchangeable terms)
In networking, a concept of a packet is the smallest unit of information that is transported over the network. An email message that you’re sending from your device to another person, that message can be broken down into small units of information that single unit of information is referred to as a packet
Those packets are sent over the network through the routers or the packet switches over the communication links to the receiver
What are packet-switching networks?
Data is broken into packets, which are then sent on the best route in the network
Each node on the route sends the packet onto its next destination, avoiding congested or broken nodes
How many nodes was ARPANET completed by and what were people able to do on it?
October 1969: ARPANET is completed with four nodes
1973: Norway connects to ARPANET via satellite, followed by London via a terrestrial link
It wasn’t a large network but for the first time across the US and internationally, people were able to sign data and exchange data with one another.
What is TCP and IP?
TCP/IP stands for Transmission Control Protocol/Internet Protocol and is a suite of communication protocols used to interconnect network devices on the internet.
(allows computers on the same network to identify and communicate with each other.)
What is the timeline from ARPANET to the Internet?
1983: TCP/IP implemented in ARPANET
1990: ARPANET is formally decommissioned
Networks similar to ARPANET sprang up around the USA and in other countries
1984: Domain name system (DNS) implemented
1985: NSFNET was established
1989: Waikato University connects to NSFNET
1991: World Wide Web (WWW) created at CERN by Tim Berners-Lee
1995: NSFNET is retired
What are some Networking Hardware?
Connection:
- Wired, e.g. Ethernet
- Wireless, e.g. Wi-Fi, cellular
Network Card:
- Can be built into the motherboard or an expansion card
- Some network cards support wired and wireless connections
To communicate over the internet, a router is required
Router:
- Directs traffic around the network and connects network together(interconnect)
(The general term for a router is a packet switch)
For multiple computers that want to connect to a single network, needs to use another type of packet switch
Switch:
- Used to connect multiple devices to the same network
Router and switch are types of packet switches but they have different functions
What’s a modem (modulator/demodulator)? what does it do? and what are the different kinds of modems?
Responsible for transmitting and receiving data on the physical medium
A modem:
- Modulates data from computer/router onto a phone line
- Demodulates signals from a phone line and sends to the computer/router
There are different kinds of modems:
- Dial-up modems up to 56Kbs
- Broadband (DSL - digital subscriber line) modems between 256Kbs to 20Mbs
What is protocol?
A protocol is a set of rules that define the format of the message that is being sent, the order of the message that is sent and received and the actions taken on transmission and the received between two communicating devices. So it defines how the connection is opened, how it is terminated, how the data is sent, how it is received and how the communication is ended
What is RFC?
(Request For Comments) A document that describes the specifications for a recommended technology.
Many protocols used in networking are defined in a RFC (Request for Comments) document
RFC 791: IP
RFC 2616: HTTP
This is a publication in series that includes specifications and notes about the internet and computing networking technologies.
What is RFC 9293: TCP?
RFC 9293: TCP - transports data reliably
Transmission Control Protocol (TCP) is also an important part of the internet. It ensures the packet reaches its destination reliably, if the packet is lost when sending to its destination, then the sender will retransmit the packet, it’s known as error detection.
At the destination or the receiver, TCP will look at the packets and then assemble them in a particular sequence to recreate the original message because the packets may not arrive in order
TCP is used in real time applications like email
What is RFC 768: UDP?
RFC 768: UDP
User Datagram Protocol (UDP) is used when users want to send the packets as quickly as possible because UDP does not offer error detection so no retransmission happens if a packet is lost and it also does not offer any flow control, it will send the packets at the fastest possible route it can
UDP is used in real time applications like videoconferencing or audio conferencing because even if lost some packets, it will just not interrupt the communication. So users may not hear certain words or video is not clear but can still communicate. But these days even video conferencing utilizes TCP
UDP: transports data faster but less reliably
What is RFC 791: IP?
Internet Protocol (IP) is the main protocol of the internet. It provides each node on a packet switched network a unique identifier and that unique identifier is called the IP address. So it’s like the location of that device on the internet
IP’s job is sending the packet from one host to another host, so every packet will have the IP address
What is RFC 2616: HTTP?
HTTP: used for client/server communication such as transferring web pages
(go to lecture 5 for more info)
