Notes / University Notes / Computer Networking / Ch3 Transport Layer

Ch3 Transport Layer

Created: 2025-11-29Updated: 2025-11-29

Getting a conversation between two processes across a network that guarantees nothing: building reliability on top, and keeping senders from flooding it.

3.1 Introduction and Transport-Layer Services

a transport-layer protocol provides for logical communication between application processes
logical communication := from an app's perspective, it's as if the hosts running the processes were directly connected
transport layer: communication between processes (segment)
network layer: communication between hosts (datagram)
TCP := Transmission Control Protocol
- reliable, in-order delivery
- congestion control; flow control
- connection setup
UDP := User Datagram Protocol
- unreliable, unordered delivery
- no-frills extension of "best-effort" IP

3.2 Multiplexing and Demultiplexing

needed at all layers
multiplexing: handle data from multiple sockets, add transport header, and pass the segments to the network layer

3.1 Introduction and Transport-Layer Services

a transport-layer protocol provides for logical communication between application processes
logical communication := from an app's perspective, it's as if the hosts running the processes were directly connected
transport layer: communication between processes (segment)
network layer: communication between hosts (datagram)
TCP := Transmission Control Protocol
- reliable, in-order delivery
- congestion control; flow control
- connection setup
UDP := User Datagram Protocol
- unreliable, unordered delivery
- no-frills extension of "best-effort" IP

3.2 Multiplexing and Demultiplexing

needed at all layers
multiplexing: handle data from multiple sockets, add transport header, and pass the segments to the network layer