ALevelComputing_Session13

Session Objectives#13 COULD explain why protocols are needed for computers to communicate

SHOULD describe what network protocols do

MUST define the term network protocol

Create a network of raspberry pis and ping to test connection.

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Protocols The word protocol means ‘a set of rules’. Therefore Network Protocol – a set of rules or standards that control the transmission of data between devices.

These rules will include that method of transmission (serial or parallel, the bit rate, transmission modes (simplex, duplex, half) and error checking. If using parity both computers would need to be using even parity or odd. If there are any differences to any of these rules then messages would be never be accepted.

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Protocol Layers Protocols are organised into “layers” which link into each other. This means it is possible to “tweak” individual layers without affecting the whole network standard. Protocols can be divide into 2 parts: logically based and physically based.

What might these 2 parts consist of? Physical

Logical

Wired or Wireless?

Concerns the data itself?

If wired, what cable to use??

Serial or parallel transmission?

Fibre optic, cat 5 e, coaxial etc

What mode to be used? Simplex etc

If wireless, what frequency, channel etc?

Bit rate to send the data at and how much to send at a time. Error checking method, parity, echo e

As you will see the logical rules that can be applied depend on the physical rules (or infrastructure) that is already in place. A-Level Computing#BristolMet

Examples of Protocols There are many protocols that have been developed over the years. TASK: Create a table and research the meaning and application Of the following protocols. Protocol Protocol DNS DNS HTTP HTTP TCP/IP TCP/IP TLS/SSL

TLS/SSL

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Meaning

Application

Meaning Domain Name System

Application Translates domain names such as bristolmet.net into IP addresses

Hypertext Transfer Protocol

For copying files from one host to another.

Transmission Control Protocol/Internet Protocol

Set of rules that organise data transmission over the internet.

Transport Layer Security/Secure Sockets Layer

Cryptographic protocols designed for secure communications

Practical Investigation TASK: Follow the ‘making a network connectiom’ tutorials and attempt to create a direct network connection to the internet using a laptop (with wifi) and a raspberry pi.

Answer the following questions: 1.What is the IP address of your raspberry pi 2.Explain what an IP address is? 3.Discuss why you cannot connect a raspberry directly to a network?

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