M15: TCP & UDP

Module 15 CISCO Networking: Compare TCP and UDP transport layer functions. Explain how TCP and UDP use port numbers.

2 Transport Layer Protocols

1. TCP

2. UDP

User Datagram Protocol

is a Transport Layer protocol used to send data quickly without worrying about reliability. It’s designed for situations where speed matters more than accuracy.

Transmission Control Protocol

is a Transport Layer protocol that provides reliable, ordered, and error‑checked delivery of data between devices. It’s used when accuracy is more important than speed.

Transport Layer

The layer of the TCP/IP model that is responsible for ensuring packets are sent reliably and any missing packets are resent.

Port Number

is a numerical identifier used at the Transport Layer (TCP/UDP) to specify which application or service data should go to on a device.

Think of an IP address as the street address, and this numbers as the apartment numbers inside the building. They act like Application addresses inside a device.

Well known port

The server-side port numbers for server run applications that listen on fixed numbers. For example HTTP server listen for requests under port 80.

Three Port Number Categories

1. Well-Known Ports

2. Registered Ports

3. Private /Dynamic Ports

Socket

Is the combination of IP address and Port number. It identifies a specific application on a specific device.

Socket Pair

Source IP : Source Port , Destination IP : Destination Port.

This pair uniquely identifies one communication session between two devices.

netstat

is a network utility that shows active TCP and UDP connections on a device.
Who am I talking to?