In data communications networks, packet segmentation is the process of dividing a data

packet Packet may refer to: * A small container or pouch ** Packet (container), a small single use container ** Cigarette packet ** Sugar packet * Network packet, a formatted unit of data carried by a packet-mode computer network * Packet radio, a fo ...

into smaller units for transmission over the network. Packet segmentation happens at layer four of the

OSI model The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communications ...

; the

transport layer In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-e ...

. Segmentation may be required when: * The data packet is larger than the

maximum transmission unit In computer networking, the maximum transmission unit (MTU) is the size of the largest protocol data unit (PDU) that can be communicated in a single network layer transaction. The MTU relates to, but is not identical to the maximum frame size tha ...

supported by the network * The network is unreliable and it is desirable to divide the information into smaller segments to maximize the probability that each one of them can be delivered correctly to the destination Protocols that perform packet segmentation at the source usually include a mechanism at the destination to reverse the process and reassemble the original packet from individual segments. This process may include automatic repeat-request (ARQ) mechanisms to detect missing segments and to request the source to re-transmit specific segments. In a communication system based on a layered

, packet segmentation may be responsible for splitting one

MPDU In telecommunications, a protocol data unit (PDU) is a single unit of information transmitted among peer entities of a computer network. It is composed of protocol-specific control information and user data. In the layered architectures of c ...

into multiple

physical layer In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer; The layer most closely associated with the physical connection between devices. This layer may be implemented by a PHY chip. The ...

service data unit In Open Systems Interconnection (OSI) terminology, a service data unit (SDU) is a unit of data that has been passed down from an OSI layer or sublayer to a lower layer. This unit of data (SDU) has not yet been encapsulated into a protocol dat ...

s so that reliable transmission (and potential re-transmission via ARQ) of each one can be performed individually. The

ITU-T The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Co ...

G.hn G.hn is a specification for home networking with data rates up to 2 Gbit/s and operation over four types of legacy wires: telephone wiring, coaxial cables, power lines and plastic optical fiber. A single G.hn semiconductor device is able to n ...

standard, which provides a way to create a high-speed (up to 1 gigabit/s)

local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a large ...

using existing home wiring (

power lines Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines that facilitate this movement form a ''transmission network''. This is d ...

, phone lines and coaxial cables), is an example of a protocol that employs packet segmentation to increase reliability over noisy media.

References

{{reflist Packets (information technology)

See also

References