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Networks 1.3.3
- Protocols and Standards
- A protocol is an agreed set
of rules defining common
methods of data
communication.
- These rules need
to be standard
across all devices
in order for them
to communicate.
- HTTP has become the
standard protocol for
browsers to render
web pages.
- TCP/IP is also used worldwide
and enables communication
with any other computer
connected to the Internet
regardless of its location.
- A protocol is an agreed set
of rules defining common
methods of data
communication.
- The TCP/IP Stack
- Networking protocols that work together
as four connected layers, passing and
outgoing data packets up and down the
layers during network communication.
- APPLICATION
LAYER
- Top of stack and provides
network services to
applications.
- Many application
network protocols work
at this layer, including
HTTP, SMTP and FTP.
- Sockets and port numbers are
used to differentiate the path
and sessions which applicatons
operate. e.g HTTP = 80, SMTP =
25 and FTP = 20/21
- Top of stack and provides
network services to
applications.
- TRANSPORT
LAYER
- Uses Transmission Control
Protocol (TCP) to establish an
end-to-end connection with the
recipient computer.
- Data is split into packets and
labelled with packet number, total
number of packets and port number
through which it should route.
- Transport layer can request
re-transmission of lost packets.
- Uses Transmission Control
Protocol (TCP) to establish an
end-to-end connection with the
recipient computer.
- INTERNET
LAYER
- Adds source and
destination IP
addresses.
- The addition of an IP
address to the port
number forms a socket
e.g. 42.205.110.140:80
- A socket specifies which device the
packet must be sent to and the
application being used on that device.
- Adds source and
destination IP
addresses.
- LINK
LAYER
- Physical connection between
network nodes and adds the
unique MAC addresses, identifying
the Network Interface Cards.
- So that once the packets finds
the correct network using the
IP address, it can then locate
the correct piece of hardware.
- Physical connection between
network nodes and adds the
unique MAC addresses, identifying
the Network Interface Cards.
- 1
- 2
- 3
- 4
- Networking protocols that work together
as four connected layers, passing and
outgoing data packets up and down the
layers during network communication.
- Switching
- Circuit
Switching
- Creates a direct link
between two devices for the
duration of the
communication.
- Two devices must transmit and receive
data at the same rate, so circuit switched
networks can only connect devices that
operate at the same transfer rate.
- As it is an exclusive
connection, packets
arrive in the same
order they are sent -
easy to reconstruct at
the other end.
- Electrical interference is
produced which can cause
packets to be lost.
- Creates a direct link
between two devices for the
duration of the
communication.
- Packet Switching
- Communicating packets of data
across a network on which other
similar communications are
happening simultaneously.
- Website data that you
receive arrives as a
series of packets and
an email will leave you
in a series of packets.
- Communicating packets of data
across a network on which other
similar communications are
happening simultaneously.
- Circuit
Switching
- Topology Types
- Bus
- Ends of the cables
are plugged into a
terminator.
- Cheap to install -
requires less cabling and
does not require any
additional hardware.
- If main cable fails, network can no
longer transmit data. Performance
degrades with heavy traffic. Low
security - all nodes can see all data.
- Ends of the cables
are plugged into a
terminator.
- Star
- Central node, which may be a
switch or computer that acts
as a router to transmit
messages.
- If one cable fails, only one station is affected. Consistent
performance when the network is being heavily used.
Higher transmission speeds. No problems with collisions of
data since each station has its own cable to the server.
Messages cannot be intercepted by other nodes. Easy to add
new stations without disrupting network.
- May be costly to install because of cable
length required. If central device goes down,
network can no longer transmit data.
- Central node, which may be a
switch or computer that acts
as a router to transmit
messages.
- Mesh
- Bus
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