Local Area Network
The PDU (protocol data unit) @ transport layer (e.g. TCP or UDP) is called as 'segment' .
2^16 bytes - size of TCP header
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.
**The TCP transport layer protocol uses windowing and acknowledgments for reliable transfer of data. **The TCP and UDP port numbers are used by application layer protocols. **The TCP transport layer protocol provides services to direct the data packets to their destination hosts.
Application layer: Data Presentation layer: Data Session layer: Data Transport layer: Segment (TCP) or Datagram (UDP) Network layer: Packet Data Link layer: Frame Physical layer: Bit
The data-link layer The physical layer
TCP The three way handshake verifies that data arrived
Segements
TCP and UDP are transport layer protocols; the OSI layer is layer 4 (transport)
The Network Interface layer
TCP and UDP are two different layer 4 protocols. TCP reliably sends data with acknowledgments and UDP sends data without checking if the destination received it. Skype uses UDP while email uses TCP.
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