A packet is a formatted unit of data sent across a network. It has a header, containing control information such as source and destination addresses, and a payload, the portion of the actual data being carried. Large messages are split into many packets and reassembled at the destination.
Why it matters
Packet switching, rather than reserving a dedicated line, is how the internet shares links efficiently among many users. Each packet can take a different path and arrive out of order, so protocols like TCP number the pieces and reorder them. Packets also set limits: an Ethernet link typically carries up to 1500 bytes of IP packet (MTU), and each router drops packets when queues overflow, which is packet loss.
Strictly, a layer-2 unit is a frame, a layer-4 TCP unit is a segment and UDP's is a datagram, though "packet" is used loosely for all.
Example
A 3 KB web response is split into about three TCP segments, each wrapped in an IP packet (20-byte IPv4 header), then in an Ethernet frame. Capturing with tcpdump shows lines like IP 203.0.113.10.443 > 192.168.1.23.51514: Flags [P.], length 1448.
Common mistakes
- Assuming all packets of one transfer follow the same route.
- Treating packets and frames as identical when debugging at different layers.
- Forgetting header overhead when calculating real throughput.
Related
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यह पेज सामान्य जानकारी है, जिसे हमारी संपादकीय टीम ने लिखा है और दस्तावेज़ीकरण बदलने पर अपडेट किया जाता है। सर्वर और प्रदाता अलग-अलग होते हैं, इसलिए बदलाव पहले सुरक्षित तरीके से जाँचें। देखें: संपादकीय नीति और अस्वीकरण.