Computer Science (0984) 2023 - 2 Data Transmission 2-1

2-1 Types and Methods of Data Transmission

Data transmission is the process of transferring data from one point to another.

2-1-1 Understand that data is broken down into packets to be transmitted; Describe the structure of a packet; Describe the process of packet switching

• Data that is sent over long distances is usually broken up into smaller parts known as data packets.
• Data packets are typically 64KiB
• Easier to control than a long stream of data
• A packet is split into 3 parts
   - header
   - payload
   - trailer
• Header
  • IP Address of sending device
  • IP Address of recieving device
  • the sequence number of the packet (allos correct reassembly)
  • packet size (bytes)
  • (Number of packets in total)
• Payload
  
  • The actual data being sent (usually 64KiB)
• Trailer
  • Method of identifying the end of a packet
  • an error checking method (see 2-2 Error Checking)
• Packet Switching
  • Each packet could take a different route
  • A router controls the route a packet takes
  • Packets may arrive out of order
  • Once the last packet has arrived, the packets are reordered.

2-1-2 Describe how data is transmitted from one device to another using different…