Packet Switching

Question 1

What is the internet

Answer 1

The internet consists of many layers ( application, transport, network, data link, physical )

To optimize a system we try to find the local optimum for each later but it is not always the global optimum.

Each layer is focused on one taks but theoretically there is a way to cross optimize between layers.

Question 2

Different layers have different environments example:

Answer 2

Routing = end to end path through a network

Forwarding= a forwarding table determines local forwarding to a specific router.

Question 3

How is data transmitted

Answer 3

Through packets

Question 4

Packet switching advantages

Answer 4

• scalable
• flexible
  ( Past used circuit switching with physical plugs )

Question 5

Protocol

Answer 5

Set of rules governing the transmission of data. ( Inform computers on the network how to identify eachother and the size of the packets you can send)

Question 6

How do packets know how to travel ?

Answer 6

Through routing algorithms that determine the sequences of routes through a network from a source to a destination.

Question 7

Global routing algorithms

Answer 7

Lead the global information of the network. All routes have a complete topology and link cost information.

Question 8

Global routing algorithms disadvantages:

Answer 8

They can be too difficult or complex and may flood the network, the internet is vast so they would need to frequently analyse the topology and restore it.

Question 9

Decentralised routing algorithms

Answer 9

The router only knows the connections to its neighbours, and link costs to its neighbours. Neighbours iteratively , exchange information with neighbours.