The document summarizes key concepts about the transport layer in the OSI model and TCP/IP model. It describes the roles and purposes of the transport layer, and compares the two main transport protocols, TCP and UDP. TCP provides reliable, connection-oriented data transfer, while UDP provides unreliable but faster data transfer. Key aspects of TCP like three-way handshakes, acknowledgements, sequence numbers, windows, and flow control are explained.

1. OSI transport layer CCNA Exploration Semester 1 – Chapter 4

4. Purpose of transport layer Responsible for the overall end-to-end transfer of application data.

6. Transport Layer TCP and UDP

10. TCP and UDP headers

12. Port numbers Client PC uses port 80. Identifies HTTP as application. Requesting a web page. Client PC uses port 49152. Chosen at random. Remembers this to identify application and conversation. Port + IP address = socket. E.g. 192.168.2.12:80

14. Netstat Shows protocol, local address and port number, foreign address and port number. Unexpected connections may mean there is a security problem.

17. Three way handshake Send SYN seq = x Receive SYN seq = x Receive SYN ack = y seq = x+1 Receive ACK ack = y+1 Send ACK ack = y+1 Send SYN ack = y seq = x+1

18. Terminating connection

25. Labs & Activities * If no previous Packet Tracer experience, else strongly recommended Mandatory* 1.2.4 PT Review carefully 1.3.3 Lab Mandatory 1.3.2 PT Mandatory 1.3.1 Lab Detail Type