Real-World Example: Sending an Email
Part of Packet Switching — GCSE Computer Science
This deep dive covers Real-World Example: Sending an Email within Packet Switching for GCSE Computer Science. Revise Packet Switching in 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 9 of 11 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 9 of 11
Practice
15 questions
Recall
18 flashcards
Real-World Example: Sending an Email
Imagine you send a 1MB email with photo attachment - here's what happens:
Step 1: Division
Your 1MB email split into ~700 packets of 1500 bytes each. Packet 1 contains first 1500 bytes, Packet 2 contains next 1500 bytes, etc.
Step 2: Headers Added
Each packet gets header: Source IP (your computer), Destination IP (recipient's mail server), Packet number (1 of 700, 2 of 700, etc.)
Step 3: Transmission
Packets leave your computer. Packet 1 might go through London → Paris → Berlin. Packet 2 might go London → Amsterdam → Berlin. Different routes!
Step 4: Routing
Routers check destination IP, forward to next hop. If Paris router is busy, packets reroute through Brussels instead. Dynamic routing!
Step 5: Arrival
Packets arrive at recipient's mail server. They might arrive: Packet 2, Packet 1, Packet 4, Packet 3... Out of order!
Step 6: Reassembly
Mail server sorts using packet numbers, reassembles into original 1MB email. Recipient downloads complete email!