Network principles

Wide area network

What is a Circuit Switched Network?
  • First a virtual circuit or path is made established between the receiver and the sender
  • Typically achieved with the use of switches
  • Data flows on the same path for the duration of communication
Give an example where a circuit switch network might be used

Telephone

What is a Packet Switched Network?
  • Data broken up into packets
  • Each packet will carry an address
  • Data is sent via packets
  • Each packet is forwarded individually between routers
  • Each packet will make its own way through the network

IP

Note this is not the only protocol used for the internet, this is one of many, however this is easily the most popular!

Is it open source?

yes

What are the two types of IP addresses?

How many bits makes up each of the following?

IPv4

Contains 32bits

IPv6

Contains 128bits

How many addresses does a individual packet hold?

Two

Therefore it must only have ether IPv4 or IPv6

What is a octet?

Another way of saying byte

How is IPv4 expressed?
  • Address is divided up into 4 octets
  • We would represent this as four numbers from 0 to 255 in decimal
  • There is a . between the numbers
How is IPv6 expressed?
  • Each group of 16bits is expressed in hex
  • There is a : between the numbers
  • IF THERE IS A 0000, WE CAN IGNORE IT so 0000 = ::
  • We can also omit leading 0's

000A:0BAD:BAD0:0000

A:BAD:BAD0:

Where are the addresses from?
  • On a LAN the ADMIN will allocate the addresses
  • On the internet the Internet Assigned Numbers Authority, will assign these IP addresses
Why have we ran out of IPv4?
  • There is only 4billion addresses
  • Many of them are reserved
  • There are loads of devices now especially with the internet of things
What will route the packets to there destination?

THE ROUUUUUTER

TCP/IP

How many protocols are in the TCP/IP suite?

Hundreds

What type of protocol is TCP?

End to end, this means that the router does not need to implement it, but the end hosts need to

What is a socket?

This then end-point of communication between two devices

The anatomy of a packet

Name the two main things that is in the header?
  • The source and destination address
How do you communicate data across a network?
  • Data is generated by a program
  • Give data and destination address to the OS
  • OS will wrap it up into a packet
  • Packet is then handed over to the Network via Network Interface
  • Network then delivers packet to destination
  • OS unwraps packet
  • Data is handed over to program