Structure of a Network Packet:

Each packet contains three parts: Header, Payload (Data), and Trailer.

1. Packet Header:

Source IP address: Where packet came from
Destination IP address: Where packet is going
Packet number: Sequence number for reassembly (e.g., packet 3 of 10)
Protocol information: TCP/UDP, etc.
Time to Live (TTL): Prevents packets looping forever

2. Payload (Data):

Actual data: The message/file content being transmitted
Size: Typically 500-1500 bytes per packet
Fragment of whole: Each packet carries small piece of total data

3. Packet Trailer (Footer):

Error checking: Checksum or CRC (Cyclic Redundancy Check)
Detects corruption: Identifies if packet was damaged during transmission
Validation: Recipient can verify data arrived correctly

This key facts covers What is a Packet? within Packet Switching for GCSE Computer Science. Revise Packet Switching in 3.5 Fundamentals of Computer Networks for GCSE Computer Science with 15 exam-style questions and 18 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 4 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.

Practice questions for Packet Switching

Which of the following best describes packet switching?

A. Data is sent as a single continuous stream along one fixed path
B. Data is split into smaller packets that may travel by different routes to the destination
C. Data is encrypted before being sent along a dedicated circuit
D. Data is compressed and stored before being forwarded to the destination

1 markfoundation

Explain why packets from the same file can travel by different routes through a network. [2 marks]

2 marksstandard

What is a Packet?

Practice questions for Packet Switching

Quick recall flashcards

15 questions on Packet Switching: practise free