Networks - Typologies and Protocols continued (Packet Switching: (It is…
Networks - Typologies and Protocols continued
MAC address example: AA-34-G4-44-23-F1
Use hex over binary for it is easier for humans to understand and there are more combinations to work with.
Uses hexadecimal as a number base
It is the physical address of the network card.
• Brings security issues.
• Convenient for connecting new devices in public areas.
• Increasingly common.
The packet's header includes the packet's destination address, the source address and the packet number.
The sending and receiving devices both calculate a checksum value by performing a function on the payload data. If both checksum values match, then the data has been received correctly.
Packets will also include a checksum number – a form of validation used to check the payload hasn't been corrupted during transit.
The data packet's payload may be part of an email, document, web page or streamed video.
Every data packet has a header – this contains the control information.
Data sent between networks is split into equal sized packets.
a unique string of numbers separated by full stops that identifies each computer using the internet Protocol to communicate over a network
• Classes C and D are used for research purposes.
Class E: 240-255 bytes
Class D: 224-239 bytes
Class C: 192-223 bytes
Class B: 128 – 191 bytes
Class A: 0-127 bytes
• This indicates the number of possible users and the purpose of the network.
• They identify the class of network that the user is on.
IP address example: 188.8.131.52
Changes over time – just assigning IP addresses to working computers
Similar to a postcode
• Ethernet connects computers within the LAN.
• Fibre optic is used outside buildings for long distances. It is very fast and very secure.
• Cable copper wire is common within buildings.
It is efficient because there are so many possible routes that data can take – packets can reach their receiving device even if there's heavy "traffic".
(6) If all data is received and the checksum match, a receipt conformation is sent to the sending device.
(5) Packets sometimes go missing in transit, so the receiving device checks periodically that all packets have been received. If not, all packets have been received then a timeout message will be sent back to the sending device.
(4) As the packets can take different routes, they can arrive in the wrong order. The receiving device uses the packet numbers to reassemble them in the right order.
(3) The way the data is sent changes depending on network traffic, so the packets can take different routes. If a router receives too many packets at once it may prioritise some over others.
(2) Each router reads the packet header and decides which way to send the packet next, according to the IP rules.
(1) The sending device splits the data into packets to be sent across the network. Each packet is given a packet number to show the order of the data.
Packet switching is used by routers to direct data packets on the Internet and other IP networks.