sequencedpacket

Sequenced packet is a discrete data unit transmitted with an accompanying sequence number that indicates its position within a logical sequence. The sequence enables receivers to detect gaps, reorder out-of-order arrivals, and verify data integrity. The concept is foundational in many networking and inter-process communication systems where data can be delivered in fragments or out of order.

Common implementations attach a header to the payload carrying a monotonically increasing sequence number, optional total length, and a checksum. Some designs use per-packet acknowledgments and a windowing scheme to control flow and ensure reliability over unreliable channels. Depending on the protocol, sequencing can be used to guarantee strict in-order delivery or to provide boundaries for messages within a stream.

Sequenced packets support reassembly of larger messages from multiple packets and help detect duplicate or missing data. In systems with strict ordering, receivers hold late packets until earlier ones arrive. In looser models, out-of-order delivery may be allowed with buffering and reordering logic. The approach can interact with congestion control, fragmentation, and error recovery mechanisms.

Sequenced packets are used in various network and IPC contexts, including message-oriented middleware, RPC-style communication, and certain transport protocols that maintain message boundaries. They contrast with unsequenced datagrams that rely on higher layers for order, and with continuous byte streams where the concept of discrete packets is not exposed to the application. See also sequencing, packet, and reassembly.