frame
frame
PACKETS
Protocol Data Unit (PDU)
A PDU (Protocol Data Unit) is defined by which layer it is in. In the physical layer and network layer, it is synonymous with the packet, in the data link layer, it is the frame. In the transport layer, it is a datagram for UDP. A datagram holds one or more PDU's, as it is the basic unit of transferring information via packet switching.
In the context of computer networking, a frame is a data unit transmitted over a computer network. Frames are classified based on the protocol layer they belong to, such as data link layer frames (e.g., Ethernet frames), network layer frames (e.g., IP packets), and transport layer frames (e.g., TCP segments). Each type of frame serves a specific purpose in transmitting and delivering data across the network.
Packet
1 tcp transmission control protocol 2 udp protocol
The PDU (protocol data unit) @ transport layer (e.g. TCP or UDP) is called as 'segment' .
In networking, PDU means "protocol data unit", and it is the generic name of the "packets" of data used at different levels of the network. Using the numbering of the OSI layers: At layer 2, the PDUs are called "frame". Example: An Ethernet frame, a frame-relay frame. At layer 3, the PDUs are called "packets". Example: An IP packet. At layer 4, the PDUs are called "segments". Example: A TCP segment, a UDP segment.
Local Area Network
In the context of smart cards, an application protocol data unit is the communication unit between a smart card reader and a smart card. The structure of the APDU is defined by ISO/IEC 7816-4 Organization, security and commands for interchange.
Layer N in the model accepts data from the next higher layer, layer N+1, in the form of a block of data known as a service data unit (SDU). To deliver this SDU to the destination system, a layer N protocol is used between the layer N entity in the source system and the layer N entity in the destination system. The source protocol entity encapsulates the SDU by adding a header and possibly a trailer, containing protocol control information, such as source and destination address and error check codes. The SDU plus header and trailer is known as a protocol data unit (PDU). An SDU may be broken up into multiple chunks and sent out in multiple PDUs, or multiple SDUs may be aggregated and send out in a single PDU, if the protocol allows it.
The units that network traffic is sent in depends on the layer of the network you are talking about, and potentially on the technology being used.For example, Ethernet uses Frames.Internet Protocol (IP) uses Packets.Asynchronous Transfer Mode (ATM) uses Cells.