GCSE Computing#BristolMet

Session Objectives#16

MUST describe the hardware needed to connect to the Internet and describe the nature of the Internet.

SHOULD explain the different roles computers play in a client server network and a peer to peer network.

COULD explain the terms IP addressing, MAC addressing, packets and protocols, and explain the need for IP addressing to manage internet resources.

Create a network of Raspberry Pis and ping to test network connections.

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Key Words

Protocol

HTTPMAC Address

Peer to Peer Client Server

IP & MAC Address

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Data Packets

When data is sent from one machine to another over a network, either through the internet or over a LAN, it needs to be collected together in bundles called packets.

Packets – bundles of data ready to be transmitted.

The size of the ‘message’ doesn’t matter as packages are a standard size, the bigger the message the more packets sent.

A data packet consists of several parts or labels

Source Address

Destination Address

PacketSequenceNumber

DATAError Checking(Checksum)

Where the fileIs coming from

Where it is going to Which part of

the file it isThe dataitself

Ensuring it is the same as original and not corrupted

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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, the bit rate, transmission modes and error checking.

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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?

As you will see the logical rules that can be applied depend on the physical rules (or infrastructure) that is already in place.

Physical LogicalPhysical 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

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Examples of Protocols

There are many protocols that have been developed over the years.TASK: Create a table and research the meaning and applicationOf the following protocols.

Protocol Meaning Application

DNS

HTTP

TCP/IP

TLS/SSL

Protocol Meaning Application

DNS Domain Name System

Translates domain names such as bristolmet.net into IP addresses

HTTP Hypertext Transfer Protocol

For copying files from one host to another.

TCP/IP Transmission Control Protocol/Internet Protocol

Set of rules that organise data transmission over the internet.

TLS/SSL Transport Layer Security/Secure Sockets Layer

Cryptographic protocols designed for secure communications

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Practical Investigation

TASK:Follow the ‘making a network connection’ 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?