CIPP/US Study Guide
Chapter 3: Introduction to Technological Aspects of Privacy

Basics of the Internet: TCP/IP and Packet Switching

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The internet is a network of networks descended from the ARPANET. Transmission control protocol (TCP) establishes reliable connections and breaks data into packets, while Internet protocol (IP) addresses and formats those packets, which travel via packet switching.

The internet has essentially the same architecture today as when first designed; its open, dynamic nature drives speed and growth but also creates privacy vulnerabilities. Transmission control protocol (TCP) establishes a reliable connection before transmitting and breaks large data into smaller packets. Internet protocol (IP) specifies the packet format and the addressing protocol - an IP address is a unique number, similar to a phone number, that shows where data should be sent.

To move data, TCP/IP relies on packet switching. The packet header directs the packet to its destination; the payload (e.g. text or video) is extracted on arrival. Different packets in the same communication may travel different routes (nodes) and are reassembled in the correct order on arrival, with missing packets retransmitted.

Header vs payload

Only the header is needed to route a packet. The payload is the actual content - this distinction matters for deep packet inspection later in the chapter.

Key terms - quick answers

What is “ARPANET”?
The 1960s U.S. military computer network that was the precursor of the modern internet.
What is “Transmission control protocol (TCP)”?
The protocol that establishes a reliable connection between source and destination and breaks data into packets while preserving integrity.
What is “Internet protocol (IP)”?
The protocol that specifies the format of data packets and provides the addressing scheme; each device gets a unique IP address (currently moving from IPv4 to IPv6).
What is “Packet switching”?
The method by which TCP/IP routes packets independently to a destination where they are reassembled in order, retransmitting any that fail to arrive.

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