Transcript 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.
A-Level Computing#BristolMet
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.
A-Level Computing#BristolMet
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
A-Level Computing#BristolMet
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?
A-Level Computing#BristolMet