Pakettiverkot

Pakettiverkot, or packet networks, are a class of digital communication networks that transmit data by breaking it into smaller units called packets. Each packet contains a portion of the original message along with addressing and control information. Packets may be routed independently, potentially along different paths, and are reassembled at the destination. This approach allows shared use of network resources and supports efficient use of bandwidth, error detection, and congestion management.

Packet switching was developed in the 1960s as an alternative to circuit switching. Pioneers like Paul Baran in the United States and Donald Davies in the United Kingdom proposed breaking messages into packets. The concept became central to ARPANET and later to the Internet, which relies on packet switching for its core protocols (IP, TCP).

In a pakettiverkko, routers examine packet headers to decide routes, with packets potentially taking different routes. There are datagram (connectionless) networks and virtual circuit networks; IP networks are generally datagram-based, while some networks establish logical paths. Reliability is provided by transport protocols such as TCP, or by higher-layer mechanisms. Fragmentation can occur to fit MTUs, but is minimized in modern networks.

Advantages include efficient bandwidth utilization, robustness to link failures, and scalability. Typical drawbacks are variable latency and jitter, possible out-of-order delivery, and header overhead. Security and QoS concerns are addressed through encryption, authentication, and traffic engineering. The Internet and most enterprise networks are examples of pakettiverkot, as are cellular data networks that carry IP traffic.