AP CSP Day 18: Packet Switching
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Packet switching breaks data into small packets that travel independently across a network and are reassembled at the destination. Each packet may take a different route through the network depending on traffic and availability. AP CSP exam questions test whether students understand why packet switching is more efficient and fault-tolerant than circuit switching, where a dedicated path is reserved for the entire transmission. Knowing that packets can arrive out of order and must be resequenced is a commonly tested detail.
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Packet Switching
How Data Travels
Data sent over the internet is broken into small chunks called packets. Each packet contains a header (source address, destination address, sequence number) and a payload (a chunk of the actual data). Packets travel independently through the network.
Why Packets?
Packet switching allows many users to share the same network links simultaneously. Different packets from the same file can take different routes and arrive out of order, then be reassembled at the destination using sequence numbers.
Practice Question
When an email is sent over the Internet, the message is divided into packets. Which of the following is true about how these packets travel?
In packet switching, individual packets can travel along different routes through the network based on availability and congestion. Each packet carries sequence information so they can be reassembled in the correct order at the destination, regardless of arrival order.
A) A key advantage of packet switching is that packets can independently find the best available route. B is correct. C) Multiple packets can travel simultaneously through different paths — this parallelism improves efficiency. D) All digital data, regardless of size, can be divided into packets for transmission.
Students think packets travel in strict sequence along a single path, like cars in a convoy. Packets are more like individual letters in the postal system — each can take a different route.
Packet switching = packets take independent paths. Circuit switching = dedicated path. The Internet uses packet switching for efficiency and fault tolerance.
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