1. TCP/IP Transport and Application (Topic 6)
Textbook:
Networking Basics, CCNA 1 Companion Guide, Cisco Press
Cisco Networking Academy Program, CCNA 1 and 2, Companion Guide, Cisco Press, Latest Edition
CIM 2465 TCP/IP Transport and Application Layers

2. TCP/IP Transport Layer (1)
Main goal of the Transport Layer
To provide the service of taking data from one application process on one computer and delivering that data to the correct application process on another computer
Compare with the Internet layer, it delivers data packets from one computer to another, but it does not think about which application sent the data or which application on the receiving computer needs the data
Key protocols
Transmission Control Protocol (TCP)
User Datagram Protocol (UDP)
TCP provides several more functions, but more overhead
CIM 2465 TCP/IP Transport and Application Layers

3. CIM 2465 TCP/IP Transport and Application Layers
TCP Vs UDP
CIM 2465 TCP/IP Transport and Application Layers

4. CIM 2465 TCP/IP Transport and Application Layers
Flow Control
When a host sends data using TCP, the receiving host can control how fast each TCP sender sends the data over time. This process is called flow control.
Why needed?
Receiver needs time to process the received data
Receiver might have a finite amount of memory for processing of data
TCP has flow-control mechanism
CIM 2465 TCP/IP Transport and Application Layers

5. Connection-Oriented Vs Conncetionless
Connectionless
The sender and receiver do not pre-arrange for communication to occur
Connection-oriented
The sender and receiver must pre-arrange for communication to occur (use messages, events, or other prearranged settings)
TCP is a connection-oriented protocol, uses a process called a three-way handshake
CIM 2465 TCP/IP Transport and Application Layers

6. Three-Way TCP Connection
CIM 2465 TCP/IP Transport and Application Layers

7. Error Recovery (Reliability)
Reliable protocols perform error recovery, which means that they ensure that all the data eventually gets to the receiver
No data loss
No data duplicated
Data received in correct sequence (in order delivery)
TCP is a reliable protocol, through the use of Acknowledgements
CIM 2465 TCP/IP Transport and Application Layers

8. CIM 2465 TCP/IP Transport and Application Layers
TCP Acknowledgements
CIM 2465 TCP/IP Transport and Application Layers

9. Segmentation, Reassembly, and In-Order Delivery
TCP segmentation refers to the process of TCP accepting a large chunk of data from application protocol and breaking it into pieces that are small enough to be appropriate for transmission
TCP on the receiving end reassembles the data into its original form, and guarantees that the data will be in order
Through the use of a Sequence Number
CIM 2465 TCP/IP Transport and Application Layers

10. CIM 2465 TCP/IP Transport and Application Layers
Port Numbers
One function performed by both UDP and TCP is providing a means to identify the specific application processes that send and receive data
Through the use of Port Numbers
< 1024, reserved, Well-Known ports
, dynamic port numbers
CIM 2465 TCP/IP Transport and Application Layers

11. CIM 2465 TCP/IP Transport and Application Layers
An IP packet with TCP segment arrives at Keith’s Computer
TCP examines the destination port number
Based on the port number, the TCP software gives the data to Browser2
CIM 2465 TCP/IP Transport and Application Layers

12. CIM 2465 TCP/IP Transport and Application Layers
Well-Know Ports (1)
CIM 2465 TCP/IP Transport and Application Layers

13. CIM 2465 TCP/IP Transport and Application Layers
Well-Know Ports (2)
CIM 2465 TCP/IP Transport and Application Layers

14. CIM 2465 TCP/IP Transport and Application Layers
TCP Header Fields
Key Fields
Source Port
Destination Port
Sequence Number
Acknowledgement Number
Checksum
CIM 2465 TCP/IP Transport and Application Layers

15. CIM 2465 TCP/IP Transport and Application Layers
TCP Header Fields
CIM 2465 TCP/IP Transport and Application Layers

16. CIM 2465 TCP/IP Transport and Application Layers
UDP Header Fields
Key Fields
Source Port
Destination Port
Length
Checksum
CIM 2465 TCP/IP Transport and Application Layers

17. TCP/IP Application Layer
TCP/IP application layer performs the same functions as defined in the top three layers of the OSI reference model
TCP/IP application protocols define the format of the data being transferred (binary or ASCII), required encryption, protocol rules for transferring data, combinations of messages (dialogues or sessions)
Application software (e.g. browsers) typically implements application layer protocols
CIM 2465 TCP/IP Transport and Application Layers

18. CIM 2465 TCP/IP Transport and Application Layers

19. Application Protocol Examples (1)
Domain Name System (DNS)
Resolves names into IP addresses
UDP
Hypertext Transfer Protocol (HTTP)
Transfers files from web servers to web browsers
TCP
Simple Mail Transfer Protocol (SMTP) and Post Office Protocol version 3 (POP3)
Send and receive , respectively
File Transfer Protocol (FTP)
Stores and retrieves files
CIM 2465 TCP/IP Transport and Application Layers

20. Application Protocol Examples (2)
Trivial File Transfer Protocol (TFTP)
Works similarly to FTP, but with some benefits when used on networking devices
UDP
Simple Network Management Protocol (SNMP)
Allows management software (the client) to query networking devices (the servers) to manage and control the networking devices
Telnet
Allows a client to emulate a terminal. It allows a user to sit at one computer (Telnet client) and use a remote computer (Telnet server) through a text-based interface
TCP
CIM 2465 TCP/IP Transport and Application Layers

21. CIM 2465 TCP/IP Transport and Application Layers
DNS
CIM 2465 TCP/IP Transport and Application Layers

22. CIM 2465 TCP/IP Transport and Application Layers
HTTP
CIM 2465 TCP/IP Transport and Application Layers

23. CIM 2465 TCP/IP Transport and Application Layers
SMTP and POP3
CIM 2465 TCP/IP Transport and Application Layers

24. CIM 2465 TCP/IP Transport and Application Layers
FTP
CIM 2465 TCP/IP Transport and Application Layers