Transport Layer INF3190 Foreleser: Carsten Griwodz Email:
[email protected] (Including slides from Michael Welzl) Transport Layer Function Transport layer tasks 5 Application Application Application 5 Layer 1. Addressing Transport Transport Transport 4 Layer Application 4 Layer Layer Layer Network Network Layer Transport Network 3 3 Layer Layer Layer Network 1-2 Layer 1-2 INF3190 - Data Communication Transport Layer Function Transport layer tasks 5 Application Application 5 1. Addressing Transport Transport 4 4 Layer Layer Network 2. End-to-end connection management Network 3 3 Layer Layer 1-2 3. Transparent data transfer 1-2 between end points 4. Quality of service • Error recovery • Reliability • Flow control • Congestion control INF3190 - Data Communication Transport Service: Terminology § Nesting of messages, packets, and frames Packet header Message header Frame header Message Payload Packet Payload Frame Payload TCP/IP Message ISO TPDU Layer Data Unit (transport protocol Transport Message data unit) Network Packet Data link Frame TCP name for Message Payload: Segment Physical Bit/symbol (bitstream) UDP name for Message: Datagram INF3190 - Data Communication Internet terminology § TCP segment could be divided across multiple IP packets (fragmentation) • hence different words used § In practice, this is inefficient and not often done § hence normally message = packet • and in everyday work, although obviously not the same: packet ≈ message or packet ≈ segment • distinction from context INF3190 - Data Communication Transport Service: