9618 · 14.1
Protocols flashcards
Revision flashcards for Cambridge 9618 Protocols (syllabus 14.1). Flip, recall, then mark a real past-paper question.
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What is a communication protocol?
A set of rules and conventions that govern the exchange of data between devices to ensure successful and meaningful communication.
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What is 'handshaking' in the context of protocols?
The process of negotiation and establishing the rules of communication between two devices before any data is transferred. It ensures both devices are ready and compatible.
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What are the three key elements of a protocol?
1. **Syntax:** The structure or format of the data (e.g., the order of bits). 2. **Semantics:** The meaning of each section of bits. 3. **Timing:** When data should be sent and how fast it can be sent.
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What is the purpose of the TCP/IP protocol suite?
To provide reliable, ordered, and error-checked delivery of a stream of data between applications running on hosts connected to an IP network. It's the foundational protocol of the internet.
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What is the difference between bit rate and baud rate?
Bit rate is the number of bits transmitted per second (bps). Baud rate is the number of signal changes (symbols) per second. One symbol can represent multiple bits.
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If a signal uses 4 voltage levels, how many bits can each symbol represent?
2 bits. With N levels, you can represent $log_2(N)$ bits. $log_2(4) = 2$.
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Describe a simplex data transmission.
Data can only be sent in one direction. For example, from a computer to a printer, or a radio broadcast.
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Describe a half-duplex data transmission.
Data can be sent in both directions, but not at the same time. For example, a walkie-talkie.
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Describe a full-duplex data transmission.
Data can be sent in both directions simultaneously. For example, a telephone conversation.
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What is a 'packet'?
A small unit of data transmitted over a network. It typically contains a header (with source/destination address, protocol info), a payload (the actual data), and a trailer (for error checking).
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Why is breaking data into packets necessary?
It allows for efficient sharing of network resources (packet switching), easier error detection and retransmission of small parts, and routing through different paths.