Transcript Rules of Packet Transmission

Rules of Packet Transmission
(Role of packet switching and routers)
How is data sent?
Payload
(the data)
Destination
Address
Source
Address
(Packet or Datagram)
When a computer wants to send a
message or a file to another
computer, it firstly separates the
file into a series of data packets.
(eg word document, MP3 etc)
Rules of Packet Transmission
File
Using datagram's
Computer
network
File
Sending a file
File
(Packet or
Datagram)
Sending the
data
Rules of Packet Transmission
(Packet or
Datagram)
Reorganising
a file
Sending the packets
(IP Address)
D
A
File, DATA
T
1
2
4
5
A
Sending
computer
Breaking up the file into
packets
3
Data packets are reassembled
(IP Address)
6
Rules of Packet Transmission
7
File, DATA
Receiving
computer
Packets via the Router
(IP Address)
D
A
T
A
Sending
computer
Packets about to be sent
out onto the Internet
The router is
instrumental in sending
packets onto their
destination
Data packets are reassembled
having reached their destination
D
(IP Address)
A
T
Rules of Packet Transmission
A
Receiving
computer
The Router Gateway
D
A
T
A
The Router Gateway
The router inspects the computer’s
address packets and sends it onto the
next router.
Rules of Packet Transmission
A ‘mish mash’ of
routers send messages
on to their destinations
The Router Gateway
D
D
A
A
T
T
A
A
Computer A
x
x
If part of the network fails, then packets
are rerouted around the failure.
Rules of Packet Transmission
Computer B
The Router Gateway
Advantages of Packet Switching
1
When sending packets, the system is able to survive a partial
network failure, as packets are rerouted
2
Packets can be rerouted around failures very quickly and set on
a new path
3
The Internet can grow very quickly as its growth is based on the
end points not on any centralised control
4
There is no need for Internet routers to notify each other as
endpoint connections are formed and dropped
5
The integrity and security of each packet sent is handled by the
endpoints, which simplifies the role of the Internet.
6
Each end point need only be aware of the router to which it is
connected and optionally a name resolution service.
Rules of Packet Transmission