04 Computer Networks

Question 1

What is the definition of computer network and what are its components?

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Answer 1

• collection of items which are compatible to each other (hardware, software, transmission procedures (protocols!!) for data transmission)
• components are for example: computer, periphery (printer, keyboard, …), telephones, special devices for networking (gateway, router, hub, …), transmission media

Question 2

Why do we have different networks?

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Answer 2

• communication network (communicating w/ friends)
• device network (using devices that are connected to another computer, e.g. printer)
• data network ( access data, e.g. downloading)
• function(ional) network (executive functions offered by servers, e.g. applying for exams via QIS)
• load network (balancing load, e.g. FH uses several servers to split up queries to the web server to some computers)
• (high) availability network (reduce unavailability of computer in risky environment, if one computer goes down you can still use others)

Question 3

The different kind of networks…

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Answer 3

…. are partially build up on top of each other, used in parallel or interconnected
…. need in oder to understand them two terms: protocol and framework

Question 4

What is…
… protocol?
… framework?

Answer 4

• protocol, is the same as a standard and is used for traffic regulation
• framekwork, which is sometimes called a reference model

Question 5

Why are standards required for computer networks?

Answer 5

• to enable differrent components to communicate there have to be rules on how this communication has to look like

Question 6

What is a standard?

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Answer 6

• consistent, widely accepted and used method to implement something
• has been established itself over other methods

Question 7

What is a protocol?

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Answer 7

• set of regulations
• define the structure of data to be sent and the process of the communication between the components of a network
• components of a network that have the same protocol implemented, are able to communicate with each other

Question 8

What is Framework?

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Answer 8

• aka reference models
• has been established to classify on an abstract level the different protocols
• are organized in layers to which the different protocols are assigned
• these layers build a hierarchy, thus protocols offer services to protocols on a higher layer

Question 9

What is ther ISO OSI reference model?

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Answer 9

• the most well-known framework
• model consists of seven layers, each taking care of specific problems
• hardly used in the real world, as more simplified models are utilised
• this is a layered model, so the protocols within each layer can be swapped without harming th eother layers!

Host layer (top down): application, presentation, session, transport
media layers (top down): network, data link, physical