Exam Tips - Packet Switching

Exam Tips - Packet Switching

Most common exam questions:

• "What is packet switching?" → Data broken into packets, each packet travels independently, reassembled at destination
• "What's in a packet?" → Header (source/dest IP, packet number), Payload (data), Trailer (error checking)
• "Advantage of packet switching?" → Efficient network use / resilient (packets reroute around failures)
• "Disadvantage of packet switching?" → Packets arrive out of order (need reassembly) / variable latency
• "Why split into packets?" → Efficient sharing of network / can reroute if failure / only retransmit lost packets

Key facts to memorize:

• Packets = small chunks (500-1500 bytes typically)
• Header contains: source/destination IP, packet number
• Trailer contains: error checking (checksum/CRC)
• Each packet can take different route
• Packets reassembled using sequence numbers

Common mistakes to avoid:

• Forgetting packets can take different routes - key feature!
• Not mentioning reassembly at destination
• Confusing packet switching with circuit switching
• Missing the three parts: header, payload, trailer

Perfect exam answer:

"Explain how packet switching works" (4 marks):

Data broken into small packets (1 mark).
Each packet has header with source/destination IP and packet number (1 mark).
Packets travel independently through network, can take different routes (1 mark).
Packets reassembled in correct order at destination using sequence numbers (1 mark).